Merge pull request #4827 from ziglang/zig-cpp

support compiling and linking c++ code

114 files changed, 30932 insertions, 121 deletions

diff --git a/cmake/Findllvm.cmake b/cmake/Findllvm.cmake
index c73ee9462e..b3a2b14f3e 100644
--- a/cmake/Findllvm.cmake
+++ b/cmake/Findllvm.cmake
@@ -7,118 +7,302 @@
 # LLVM_LIBRARIES
 # LLVM_LIBDIRS
 
-find_program(LLVM_CONFIG_EXE
-    NAMES llvm-config-10 llvm-config-10.0 llvm-config100 llvm-config
-    PATHS
-        "/mingw64/bin"
-        "/c/msys64/mingw64/bin"
-        "c:/msys64/mingw64/bin"
-        "C:/Libraries/llvm-10.0.0/bin")
-
-if ("${LLVM_CONFIG_EXE}" STREQUAL "LLVM_CONFIG_EXE-NOTFOUND")
-  message(FATAL_ERROR "unable to find llvm-config")
-endif()
-
-if ("${LLVM_CONFIG_EXE}" STREQUAL "LLVM_CONFIG_EXE-NOTFOUND")
-  message(FATAL_ERROR "unable to find llvm-config")
-endif()
-
-execute_process(
-	COMMAND ${LLVM_CONFIG_EXE} --version
-	OUTPUT_VARIABLE LLVM_CONFIG_VERSION
-	OUTPUT_STRIP_TRAILING_WHITESPACE)
-
-if("${LLVM_CONFIG_VERSION}" VERSION_LESS 10)
-  message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
-endif()
-if("${LLVM_CONFIG_VERSION}" VERSION_EQUAL 11)
-  message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
-endif()
-if("${LLVM_CONFIG_VERSION}" VERSION_GREATER 11)
-  message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
-endif()
-
-execute_process(
-	COMMAND ${LLVM_CONFIG_EXE} --targets-built
-    OUTPUT_VARIABLE LLVM_TARGETS_BUILT_SPACES
-	OUTPUT_STRIP_TRAILING_WHITESPACE)
-string(REPLACE " " ";" LLVM_TARGETS_BUILT "${LLVM_TARGETS_BUILT_SPACES}")
-function(NEED_TARGET TARGET_NAME)
-    list (FIND LLVM_TARGETS_BUILT "${TARGET_NAME}" _index)
-    if (${_index} EQUAL -1)
-        message(FATAL_ERROR "LLVM is missing target ${TARGET_NAME}. Zig requires LLVM to be built with all default targets enabled.")
-    endif()
-endfunction(NEED_TARGET)
-NEED_TARGET("AArch64")
-NEED_TARGET("AMDGPU")
-NEED_TARGET("ARM")
-NEED_TARGET("BPF")
-NEED_TARGET("Hexagon")
-NEED_TARGET("Lanai")
-NEED_TARGET("Mips")
-NEED_TARGET("MSP430")
-NEED_TARGET("NVPTX")
-NEED_TARGET("PowerPC")
-NEED_TARGET("RISCV")
-NEED_TARGET("Sparc")
-NEED_TARGET("SystemZ")
-NEED_TARGET("WebAssembly")
-NEED_TARGET("X86")
-NEED_TARGET("XCore")
+if(ZIG_CROSSCOMPILING)
+  # Here we assume that we're cross compiling with Zig, of course. No reason
+  # to support more complicated setups. We also assume the experimental target
+  # AVR is enabled.
 
-if(ZIG_STATIC_LLVM)
-  execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --libfiles --link-static
-      OUTPUT_VARIABLE LLVM_LIBRARIES_SPACES
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_LIBRARIES "${LLVM_LIBRARIES_SPACES}")
+  find_path(LLVM_INCLUDE_DIRS NAMES llvm/IR/IRBuilder.h
+    PATHS
+        /usr/lib/llvm/10/include
+        /usr/lib/llvm-10/include
+        /usr/lib/llvm-10.0/include
+        /usr/local/llvm100/include
+        /mingw64/include)
 
-  execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --system-libs --link-static
-      OUTPUT_VARIABLE LLVM_SYSTEM_LIBS_SPACES
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_SYSTEM_LIBS "${LLVM_SYSTEM_LIBS_SPACES}")
+    macro(FIND_AND_ADD_LLVM_LIB _libname_)
+      string(TOUPPER ${_libname_} _prettylibname_)
+      find_library(LLVM_${_prettylibname_}_LIB NAMES ${_libname_}
+        PATHS
+        ${LLVM_LIBDIRS}
+        /usr/lib/llvm/10/lib
+        /usr/lib/llvm-10/lib
+        /usr/lib/llvm-10.0/lib
+        /usr/local/llvm100/lib
+        /mingw64/lib
+        /c/msys64/mingw64/lib
+        c:\\msys64\\mingw64\\lib)
+      if(LLVM_${_prettylibname_}_LIB)
+        set(LLVM_LIBRARIES ${LLVM_LIBRARIES} ${LLVM_${_prettylibname_}_LIB})
+      endif()
+    endmacro(FIND_AND_ADD_LLVM_LIB)
 
+    # This list can be re-generated with `llvm-config --libfiles` and then
+    # reformatting using your favorite text editor. Note we do not execute
+    # `llvm-config` here because we are cross compiling.
+    FIND_AND_ADD_LLVM_LIB(LLVMXRay)
+    FIND_AND_ADD_LLVM_LIB(LLVMWindowsManifest)
+    FIND_AND_ADD_LLVM_LIB(LLVMTableGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMSymbolize)
+    FIND_AND_ADD_LLVM_LIB(LLVMDebugInfoPDB)
+    FIND_AND_ADD_LLVM_LIB(LLVMOrcJIT)
+    FIND_AND_ADD_LLVM_LIB(LLVMOrcError)
+    FIND_AND_ADD_LLVM_LIB(LLVMJITLink)
+    FIND_AND_ADD_LLVM_LIB(LLVMObjectYAML)
+    FIND_AND_ADD_LLVM_LIB(LLVMMCA)
+    FIND_AND_ADD_LLVM_LIB(LLVMLTO)
+    FIND_AND_ADD_LLVM_LIB(LLVMPasses)
+    FIND_AND_ADD_LLVM_LIB(LLVMObjCARCOpts)
+    FIND_AND_ADD_LLVM_LIB(LLVMLineEditor)
+    FIND_AND_ADD_LLVM_LIB(LLVMLibDriver)
+    FIND_AND_ADD_LLVM_LIB(LLVMInterpreter)
+    FIND_AND_ADD_LLVM_LIB(LLVMFuzzMutate)
+    FIND_AND_ADD_LLVM_LIB(LLVMFrontendOpenMP)
+    FIND_AND_ADD_LLVM_LIB(LLVMMCJIT)
+    FIND_AND_ADD_LLVM_LIB(LLVMExecutionEngine)
+    FIND_AND_ADD_LLVM_LIB(LLVMRuntimeDyld)
+    FIND_AND_ADD_LLVM_LIB(LLVMDWARFLinker)
+    FIND_AND_ADD_LLVM_LIB(LLVMDlltoolDriver)
+    FIND_AND_ADD_LLVM_LIB(LLVMOption)
+    FIND_AND_ADD_LLVM_LIB(LLVMDebugInfoGSYM)
+    FIND_AND_ADD_LLVM_LIB(LLVMCoverage)
+    FIND_AND_ADD_LLVM_LIB(LLVMCoroutines)
+    FIND_AND_ADD_LLVM_LIB(LLVMAVRDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMAVRCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMAVRAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMAVRDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMAVRInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMXCoreDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMXCoreCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMXCoreDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMXCoreInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86Disassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86AsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86CodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86Desc)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86Utils)
+    FIND_AND_ADD_LLVM_LIB(LLVMX86Info)
+    FIND_AND_ADD_LLVM_LIB(LLVMWebAssemblyDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMWebAssemblyCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMWebAssemblyDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMWebAssemblyAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMWebAssemblyInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMSystemZDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMSystemZCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMSystemZAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMSystemZDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMSystemZInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMSparcDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMSparcCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMSparcAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMSparcDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMSparcInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVUtils)
+    FIND_AND_ADD_LLVM_LIB(LLVMRISCVInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMPowerPCDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMPowerPCCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMPowerPCAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMPowerPCDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMPowerPCInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMNVPTXCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMNVPTXDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMNVPTXInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMMSP430Disassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMMSP430CodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMMSP430AsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMMSP430Desc)
+    FIND_AND_ADD_LLVM_LIB(LLVMMSP430Info)
+    FIND_AND_ADD_LLVM_LIB(LLVMMipsDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMMipsCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMMipsAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMMipsDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMMipsInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMLanaiDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMLanaiCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMLanaiAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMLanaiDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMLanaiInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMHexagonDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMHexagonCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMHexagonAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMHexagonDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMHexagonInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMBPFDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMBPFCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMBPFAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMBPFDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMBPFInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMUtils)
+    FIND_AND_ADD_LLVM_LIB(LLVMARMInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMMIRParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMipo)
+    FIND_AND_ADD_LLVM_LIB(LLVMInstrumentation)
+    FIND_AND_ADD_LLVM_LIB(LLVMVectorize)
+    FIND_AND_ADD_LLVM_LIB(LLVMLinker)
+    FIND_AND_ADD_LLVM_LIB(LLVMIRReader)
+    FIND_AND_ADD_LLVM_LIB(LLVMAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUAsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUDesc)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUUtils)
+    FIND_AND_ADD_LLVM_LIB(LLVMAMDGPUInfo)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64Disassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMMCDisassembler)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64CodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMCFGuard)
+    FIND_AND_ADD_LLVM_LIB(LLVMGlobalISel)
+    FIND_AND_ADD_LLVM_LIB(LLVMSelectionDAG)
+    FIND_AND_ADD_LLVM_LIB(LLVMAsmPrinter)
+    FIND_AND_ADD_LLVM_LIB(LLVMDebugInfoDWARF)
+    FIND_AND_ADD_LLVM_LIB(LLVMCodeGen)
+    FIND_AND_ADD_LLVM_LIB(LLVMTarget)
+    FIND_AND_ADD_LLVM_LIB(LLVMScalarOpts)
+    FIND_AND_ADD_LLVM_LIB(LLVMInstCombine)
+    FIND_AND_ADD_LLVM_LIB(LLVMAggressiveInstCombine)
+    FIND_AND_ADD_LLVM_LIB(LLVMTransformUtils)
+    FIND_AND_ADD_LLVM_LIB(LLVMBitWriter)
+    FIND_AND_ADD_LLVM_LIB(LLVMAnalysis)
+    FIND_AND_ADD_LLVM_LIB(LLVMProfileData)
+    FIND_AND_ADD_LLVM_LIB(LLVMObject)
+    FIND_AND_ADD_LLVM_LIB(LLVMTextAPI)
+    FIND_AND_ADD_LLVM_LIB(LLVMBitReader)
+    FIND_AND_ADD_LLVM_LIB(LLVMCore)
+    FIND_AND_ADD_LLVM_LIB(LLVMRemarks)
+    FIND_AND_ADD_LLVM_LIB(LLVMBitstreamReader)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64AsmParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMMCParser)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64Desc)
+    FIND_AND_ADD_LLVM_LIB(LLVMMC)
+    FIND_AND_ADD_LLVM_LIB(LLVMDebugInfoCodeView)
+    FIND_AND_ADD_LLVM_LIB(LLVMDebugInfoMSF)
+    FIND_AND_ADD_LLVM_LIB(LLVMBinaryFormat)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64Utils)
+    FIND_AND_ADD_LLVM_LIB(LLVMAArch64Info)
+    FIND_AND_ADD_LLVM_LIB(LLVMSupport)
+    FIND_AND_ADD_LLVM_LIB(LLVMDemangle)
+else()
+  find_program(LLVM_CONFIG_EXE
+      NAMES llvm-config-10 llvm-config-10.0 llvm-config100 llvm-config
+      PATHS
+          "/mingw64/bin"
+          "/c/msys64/mingw64/bin"
+          "c:/msys64/mingw64/bin"
+          "C:/Libraries/llvm-10.0.0/bin")
+  
+  if ("${LLVM_CONFIG_EXE}" STREQUAL "LLVM_CONFIG_EXE-NOTFOUND")
+    message(FATAL_ERROR "unable to find llvm-config")
+  endif()
+  
+  if ("${LLVM_CONFIG_EXE}" STREQUAL "LLVM_CONFIG_EXE-NOTFOUND")
+    message(FATAL_ERROR "unable to find llvm-config")
+  endif()
+  
   execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --libdir --link-static
-      OUTPUT_VARIABLE LLVM_LIBDIRS_SPACES
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_LIBDIRS "${LLVM_LIBDIRS_SPACES}")
-endif()
-if(NOT LLVM_LIBRARIES)
-  execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --libs
-      OUTPUT_VARIABLE LLVM_LIBRARIES_SPACES
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_LIBRARIES "${LLVM_LIBRARIES_SPACES}")
-
+  	COMMAND ${LLVM_CONFIG_EXE} --version
+  	OUTPUT_VARIABLE LLVM_CONFIG_VERSION
+  	OUTPUT_STRIP_TRAILING_WHITESPACE)
+  
+  if("${LLVM_CONFIG_VERSION}" VERSION_LESS 10)
+    message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
+  endif()
+  if("${LLVM_CONFIG_VERSION}" VERSION_EQUAL 11)
+    message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
+  endif()
+  if("${LLVM_CONFIG_VERSION}" VERSION_GREATER 11)
+    message(FATAL_ERROR "expected LLVM 10.x but found ${LLVM_CONFIG_VERSION}")
+  endif()
+  
   execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --system-libs
-      OUTPUT_VARIABLE LLVM_SYSTEM_LIBS_SPACES
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_SYSTEM_LIBS "${LLVM_SYSTEM_LIBS_SPACES}")
-
+  	COMMAND ${LLVM_CONFIG_EXE} --targets-built
+      OUTPUT_VARIABLE LLVM_TARGETS_BUILT_SPACES
+  	OUTPUT_STRIP_TRAILING_WHITESPACE)
+  string(REPLACE " " ";" LLVM_TARGETS_BUILT "${LLVM_TARGETS_BUILT_SPACES}")
+  function(NEED_TARGET TARGET_NAME)
+      list (FIND LLVM_TARGETS_BUILT "${TARGET_NAME}" _index)
+      if (${_index} EQUAL -1)
+          message(FATAL_ERROR "LLVM is missing target ${TARGET_NAME}. Zig requires LLVM to be built with all default targets enabled.")
+      endif()
+  endfunction(NEED_TARGET)
+  NEED_TARGET("AArch64")
+  NEED_TARGET("AMDGPU")
+  NEED_TARGET("ARM")
+  NEED_TARGET("BPF")
+  NEED_TARGET("Hexagon")
+  NEED_TARGET("Lanai")
+  NEED_TARGET("Mips")
+  NEED_TARGET("MSP430")
+  NEED_TARGET("NVPTX")
+  NEED_TARGET("PowerPC")
+  NEED_TARGET("RISCV")
+  NEED_TARGET("Sparc")
+  NEED_TARGET("SystemZ")
+  NEED_TARGET("WebAssembly")
+  NEED_TARGET("X86")
+  NEED_TARGET("XCore")
+  
+  if(ZIG_STATIC_LLVM)
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --libfiles --link-static
+        OUTPUT_VARIABLE LLVM_LIBRARIES_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_LIBRARIES "${LLVM_LIBRARIES_SPACES}")
+  
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --system-libs --link-static
+        OUTPUT_VARIABLE LLVM_SYSTEM_LIBS_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_SYSTEM_LIBS "${LLVM_SYSTEM_LIBS_SPACES}")
+  
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --libdir --link-static
+        OUTPUT_VARIABLE LLVM_LIBDIRS_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_LIBDIRS "${LLVM_LIBDIRS_SPACES}")
+  endif()
+  if(NOT LLVM_LIBRARIES)
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --libs
+        OUTPUT_VARIABLE LLVM_LIBRARIES_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_LIBRARIES "${LLVM_LIBRARIES_SPACES}")
+  
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --system-libs
+        OUTPUT_VARIABLE LLVM_SYSTEM_LIBS_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_SYSTEM_LIBS "${LLVM_SYSTEM_LIBS_SPACES}")
+  
+    execute_process(
+        COMMAND ${LLVM_CONFIG_EXE} --libdir
+        OUTPUT_VARIABLE LLVM_LIBDIRS_SPACES
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    string(REPLACE " " ";" LLVM_LIBDIRS "${LLVM_LIBDIRS_SPACES}")
+  endif()
+  
   execute_process(
-      COMMAND ${LLVM_CONFIG_EXE} --libdir
-      OUTPUT_VARIABLE LLVM_LIBDIRS_SPACES
+      COMMAND ${LLVM_CONFIG_EXE} --includedir
+      OUTPUT_VARIABLE LLVM_INCLUDE_DIRS
       OUTPUT_STRIP_TRAILING_WHITESPACE)
-  string(REPLACE " " ";" LLVM_LIBDIRS "${LLVM_LIBDIRS_SPACES}")
+  
+  set(LLVM_LIBRARIES ${LLVM_LIBRARIES} ${LLVM_SYSTEM_LIBS})
+  
+  if(NOT LLVM_LIBRARIES)
+    find_library(LLVM_LIBRARIES NAMES LLVM LLVM-10 LLVM-10.0)
+  endif()
+  
+  link_directories("${CMAKE_PREFIX_PATH}/lib")
+  link_directories("${LLVM_LIBDIRS}")
 endif()
 
-execute_process(
-    COMMAND ${LLVM_CONFIG_EXE} --includedir
-    OUTPUT_VARIABLE LLVM_INCLUDE_DIRS
-    OUTPUT_STRIP_TRAILING_WHITESPACE)
-
-set(LLVM_LIBRARIES ${LLVM_LIBRARIES} ${LLVM_SYSTEM_LIBS})
-
-if(NOT LLVM_LIBRARIES)
-  find_library(LLVM_LIBRARIES NAMES LLVM LLVM-10 LLVM-10.0)
-endif()
-
-link_directories("${CMAKE_PREFIX_PATH}/lib")
-link_directories("${LLVM_LIBDIRS}")
-
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(llvm DEFAULT_MSG LLVM_LIBRARIES LLVM_INCLUDE_DIRS)
 
diff --git a/lib/libc/mingw/misc/_create_locale.c b/lib/libc/mingw/misc/_create_locale.c
new file mode 100644
index 0000000000..00947b3ac1
--- /dev/null
+++ b/lib/libc/mingw/misc/_create_locale.c
@@ -0,0 +1,33 @@
+/**
+ * This file has no copyright assigned and is placed in the Public Domain.
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER.PD within this package.
+ */
+
+#include <windows.h>
+#include <locale.h>
+#include <msvcrt.h>
+
+static _locale_t __cdecl init_func(int category, const char *locale);
+_locale_t (__cdecl *__MINGW_IMP_SYMBOL(_create_locale))(int, const char *) = init_func;
+
+static _locale_t __cdecl null_func(int category, const char *locale)
+{
+  (void)category;
+  (void)locale;
+  return NULL;
+}
+
+static _locale_t __cdecl init_func(int category, const char *locale)
+{
+    HMODULE msvcrt = __mingw_get_msvcrt_handle();
+    _locale_t (__cdecl *func)(int, const char *) = NULL;
+
+    if (msvcrt)
+        func = (void*)GetProcAddress(msvcrt, "_create_locale");
+
+    if (!func)
+        func = null_func;
+
+    return (__MINGW_IMP_SYMBOL(_create_locale) = func)(category, locale);
+}
diff --git a/lib/libc/mingw/misc/_free_locale.c b/lib/libc/mingw/misc/_free_locale.c
new file mode 100644
index 0000000000..d94e2274fa
--- /dev/null
+++ b/lib/libc/mingw/misc/_free_locale.c
@@ -0,0 +1,31 @@
+/**
+ * This file has no copyright assigned and is placed in the Public Domain.
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER.PD within this package.
+ */
+
+#include <windows.h>
+#include <locale.h>
+#include <msvcrt.h>
+
+static void __cdecl init_func(_locale_t locale);
+void (__cdecl *__MINGW_IMP_SYMBOL(_free_locale))(_locale_t) = init_func;
+
+static void __cdecl stub_func(_locale_t locale)
+{
+  (void)locale;
+}
+
+static void __cdecl init_func(_locale_t locale)
+{
+    HMODULE msvcrt = __mingw_get_msvcrt_handle();
+    void (__cdecl *func)(_locale_t) = NULL;
+
+    if (msvcrt)
+        func = (void*)GetProcAddress(msvcrt, "_free_locale");
+
+    if (!func)
+        func = stub_func;
+
+    (__MINGW_IMP_SYMBOL(_free_locale) = func)(locale);
+}
diff --git a/lib/libcxx/src/algorithm.cpp b/lib/libcxx/src/algorithm.cpp
new file mode 100644
index 0000000000..40669fb9e7
--- /dev/null
+++ b/lib/libcxx/src/algorithm.cpp
@@ -0,0 +1,95 @@
+//===----------------------- algorithm.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "algorithm"
+#include "random"
+#ifndef _LIBCPP_HAS_NO_THREADS
+#include "mutex"
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template void __sort<__less<char>&, char*>(char*, char*, __less<char>&);
+template void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&);
+template void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&);
+template void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&);
+template void __sort<__less<short>&, short*>(short*, short*, __less<short>&);
+template void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&);
+template void __sort<__less<int>&, int*>(int*, int*, __less<int>&);
+template void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&);
+template void __sort<__less<long>&, long*>(long*, long*, __less<long>&);
+template void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&);
+template void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&);
+template void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&);
+template void __sort<__less<float>&, float*>(float*, float*, __less<float>&);
+template void __sort<__less<double>&, double*>(double*, double*, __less<double>&);
+template void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&);
+
+template bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&);
+template bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&);
+template bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&);
+template bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&);
+template bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&);
+template bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&);
+template bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&);
+template bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&);
+template bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&);
+template bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&);
+template bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&);
+template bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&);
+template bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&);
+template bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&);
+template bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&);
+
+template unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&);
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+_LIBCPP_SAFE_STATIC static __libcpp_mutex_t __rs_mut = _LIBCPP_MUTEX_INITIALIZER;
+#endif
+unsigned __rs_default::__c_ = 0;
+
+__rs_default::__rs_default()
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    __libcpp_mutex_lock(&__rs_mut);
+#endif
+    __c_ = 1;
+}
+
+__rs_default::__rs_default(const __rs_default&)
+{
+    ++__c_;
+}
+
+__rs_default::~__rs_default()
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    if (--__c_ == 0)
+       __libcpp_mutex_unlock(&__rs_mut);
+#else
+    --__c_;
+#endif
+}
+
+__rs_default::result_type
+__rs_default::operator()()
+{
+    static mt19937 __rs_g;
+    return __rs_g();
+}
+
+__rs_default
+__rs_get()
+{
+    return __rs_default();
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/any.cpp b/lib/libcxx/src/any.cpp
new file mode 100644
index 0000000000..0cf0906883
--- /dev/null
+++ b/lib/libcxx/src/any.cpp
@@ -0,0 +1,34 @@
+//===---------------------------- any.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "any"
+
+namespace std {
+const char* bad_any_cast::what() const _NOEXCEPT {
+    return "bad any cast";
+}
+}
+
+
+#include <experimental/__config>
+
+//  Preserve std::experimental::any_bad_cast for ABI compatibility
+//  Even though it no longer exists in a header file
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
+class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_ANY_CAST bad_any_cast : public bad_cast
+{
+public:
+    virtual const char* what() const _NOEXCEPT;
+};
+
+const char* bad_any_cast::what() const _NOEXCEPT {
+    return "bad any cast";
+}
+
+_LIBCPP_END_NAMESPACE_LFTS
diff --git a/lib/libcxx/src/bind.cpp b/lib/libcxx/src/bind.cpp
new file mode 100644
index 0000000000..53efdf9df3
--- /dev/null
+++ b/lib/libcxx/src/bind.cpp
@@ -0,0 +1,29 @@
+//===-------------------------- bind.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "functional"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace placeholders
+{
+
+const __ph<1>   _1{};
+const __ph<2>   _2{};
+const __ph<3>   _3{};
+const __ph<4>   _4{};
+const __ph<5>   _5{};
+const __ph<6>   _6{};
+const __ph<7>   _7{};
+const __ph<8>   _8{};
+const __ph<9>   _9{};
+const __ph<10> _10{};
+
+}  // placeholders
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/charconv.cpp b/lib/libcxx/src/charconv.cpp
new file mode 100644
index 0000000000..d3035883a7
--- /dev/null
+++ b/lib/libcxx/src/charconv.cpp
@@ -0,0 +1,160 @@
+//===------------------------- charconv.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "charconv"
+#include <string.h>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace __itoa
+{
+
+static constexpr char cDigitsLut[200] = {
+    '0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0',
+    '7', '0', '8', '0', '9', '1', '0', '1', '1', '1', '2', '1', '3', '1', '4',
+    '1', '5', '1', '6', '1', '7', '1', '8', '1', '9', '2', '0', '2', '1', '2',
+    '2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9',
+    '3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3',
+    '7', '3', '8', '3', '9', '4', '0', '4', '1', '4', '2', '4', '3', '4', '4',
+    '4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '5', '0', '5', '1', '5',
+    '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
+    '6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6',
+    '7', '6', '8', '6', '9', '7', '0', '7', '1', '7', '2', '7', '3', '7', '4',
+    '7', '5', '7', '6', '7', '7', '7', '8', '7', '9', '8', '0', '8', '1', '8',
+    '2', '8', '3', '8', '4', '8', '5', '8', '6', '8', '7', '8', '8', '8', '9',
+    '9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9', '5', '9', '6', '9',
+    '7', '9', '8', '9', '9'};
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append1(char* buffer, T i)
+{
+    *buffer = '0' + static_cast<char>(i);
+    return buffer + 1;
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append2(char* buffer, T i)
+{
+    memcpy(buffer, &cDigitsLut[(i)*2], 2);
+    return buffer + 2;
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append3(char* buffer, T i)
+{
+    return append2(append1(buffer, (i) / 100), (i) % 100);
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append4(char* buffer, T i)
+{
+    return append2(append2(buffer, (i) / 100), (i) % 100);
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append2_no_zeros(char* buffer, T v)
+{
+    if (v < 10)
+        return append1(buffer, v);
+    else
+        return append2(buffer, v);
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append4_no_zeros(char* buffer, T v)
+{
+    if (v < 100)
+        return append2_no_zeros(buffer, v);
+    else if (v < 1000)
+        return append3(buffer, v);
+    else
+        return append4(buffer, v);
+}
+
+template <typename T>
+inline _LIBCPP_INLINE_VISIBILITY char*
+append8_no_zeros(char* buffer, T v)
+{
+    if (v < 10000)
+    {
+        buffer = append4_no_zeros(buffer, v);
+    }
+    else
+    {
+        buffer = append4_no_zeros(buffer, v / 10000);
+        buffer = append4(buffer, v % 10000);
+    }
+    return buffer;
+}
+
+char*
+__u32toa(uint32_t value, char* buffer)
+{
+    if (value < 100000000)
+    {
+        buffer = append8_no_zeros(buffer, value);
+    }
+    else
+    {
+        // value = aabbbbcccc in decimal
+        const uint32_t a = value / 100000000;  // 1 to 42
+        value %= 100000000;
+
+        buffer = append2_no_zeros(buffer, a);
+        buffer = append4(buffer, value / 10000);
+        buffer = append4(buffer, value % 10000);
+    }
+
+    return buffer;
+}
+
+char*
+__u64toa(uint64_t value, char* buffer)
+{
+    if (value < 100000000)
+    {
+        uint32_t v = static_cast<uint32_t>(value);
+        buffer = append8_no_zeros(buffer, v);
+    }
+    else if (value < 10000000000000000)
+    {
+        const uint32_t v0 = static_cast<uint32_t>(value / 100000000);
+        const uint32_t v1 = static_cast<uint32_t>(value % 100000000);
+
+        buffer = append8_no_zeros(buffer, v0);
+        buffer = append4(buffer, v1 / 10000);
+        buffer = append4(buffer, v1 % 10000);
+    }
+    else
+    {
+        const uint32_t a =
+            static_cast<uint32_t>(value / 10000000000000000);  // 1 to 1844
+        value %= 10000000000000000;
+
+        buffer = append4_no_zeros(buffer, a);
+
+        const uint32_t v0 = static_cast<uint32_t>(value / 100000000);
+        const uint32_t v1 = static_cast<uint32_t>(value % 100000000);
+        buffer = append4(buffer, v0 / 10000);
+        buffer = append4(buffer, v0 % 10000);
+        buffer = append4(buffer, v1 / 10000);
+        buffer = append4(buffer, v1 % 10000);
+    }
+
+    return buffer;
+}
+
+}  // namespace __itoa
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/chrono.cpp b/lib/libcxx/src/chrono.cpp
new file mode 100644
index 0000000000..9d448b6a98
--- /dev/null
+++ b/lib/libcxx/src/chrono.cpp
@@ -0,0 +1,233 @@
+//===------------------------- chrono.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "chrono"
+#include "cerrno"        // errno
+#include "system_error"  // __throw_system_error
+#include <time.h>        // clock_gettime, CLOCK_MONOTONIC and CLOCK_REALTIME
+#include "include/apple_availability.h"
+
+#if !defined(__APPLE__)
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif // __APPLE__
+
+#if defined(_LIBCPP_WIN32API)
+#define WIN32_LEAN_AND_MEAN
+#define VC_EXTRA_LEAN
+#include <windows.h>
+#if _WIN32_WINNT >= _WIN32_WINNT_WIN8
+#include <winapifamily.h>
+#endif
+#else
+#if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME)
+#include <sys/time.h>        // for gettimeofday and timeval
+#endif // !defined(CLOCK_REALTIME)
+#endif // defined(_LIBCPP_WIN32API)
+
+#if !defined(_LIBCPP_HAS_NO_MONOTONIC_CLOCK)
+#if __APPLE__
+#include <mach/mach_time.h>  // mach_absolute_time, mach_timebase_info_data_t
+#elif !defined(_LIBCPP_WIN32API) && !defined(CLOCK_MONOTONIC)
+#error "Monotonic clock not implemented"
+#endif
+#endif
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB)
+#pragma comment(lib, "rt")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace chrono
+{
+
+// system_clock
+
+const bool system_clock::is_steady;
+
+system_clock::time_point
+system_clock::now() _NOEXCEPT
+{
+#if defined(_LIBCPP_WIN32API)
+  // FILETIME is in 100ns units
+  using filetime_duration =
+      _VSTD::chrono::duration<__int64,
+                              _VSTD::ratio_multiply<_VSTD::ratio<100, 1>,
+                                                    nanoseconds::period>>;
+
+  // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970.
+  static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600};
+
+  FILETIME ft;
+#if _WIN32_WINNT >= _WIN32_WINNT_WIN8
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
+  GetSystemTimePreciseAsFileTime(&ft);
+#else
+  GetSystemTimeAsFileTime(&ft);
+#endif
+#else
+  GetSystemTimeAsFileTime(&ft);
+#endif
+
+  filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) |
+                       static_cast<__int64>(ft.dwLowDateTime)};
+  return time_point(duration_cast<duration>(d - nt_to_unix_epoch));
+#else
+#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_REALTIME)
+  struct timespec tp;
+  if (0 != clock_gettime(CLOCK_REALTIME, &tp))
+    __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");
+  return time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000));
+#else
+    timeval tv;
+    gettimeofday(&tv, 0);
+    return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
+#endif // _LIBCPP_USE_CLOCK_GETTIME && CLOCK_REALTIME
+#endif
+}
+
+time_t
+system_clock::to_time_t(const time_point& t) _NOEXCEPT
+{
+    return time_t(duration_cast<seconds>(t.time_since_epoch()).count());
+}
+
+system_clock::time_point
+system_clock::from_time_t(time_t t) _NOEXCEPT
+{
+    return system_clock::time_point(seconds(t));
+}
+
+#ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK
+// steady_clock
+//
+// Warning:  If this is not truly steady, then it is non-conforming.  It is
+//  better for it to not exist and have the rest of libc++ use system_clock
+//  instead.
+
+const bool steady_clock::is_steady;
+
+#if defined(__APPLE__)
+
+// Darwin libc versions >= 1133 provide ns precision via CLOCK_UPTIME_RAW
+#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_UPTIME_RAW)
+steady_clock::time_point
+steady_clock::now() _NOEXCEPT
+{
+    struct timespec tp;
+    if (0 != clock_gettime(CLOCK_UPTIME_RAW, &tp))
+        __throw_system_error(errno, "clock_gettime(CLOCK_UPTIME_RAW) failed");
+    return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
+}
+
+#else
+//   mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of
+//   nanoseconds since the computer booted up.  MachInfo.numer and MachInfo.denom
+//   are run time constants supplied by the OS.  This clock has no relationship
+//   to the Gregorian calendar.  It's main use is as a high resolution timer.
+
+// MachInfo.numer / MachInfo.denom is often 1 on the latest equipment.  Specialize
+//   for that case as an optimization.
+
+static
+steady_clock::rep
+steady_simplified()
+{
+    return static_cast<steady_clock::rep>(mach_absolute_time());
+}
+
+static
+double
+compute_steady_factor()
+{
+    mach_timebase_info_data_t MachInfo;
+    mach_timebase_info(&MachInfo);
+    return static_cast<double>(MachInfo.numer) / MachInfo.denom;
+}
+
+static
+steady_clock::rep
+steady_full()
+{
+    static const double factor = compute_steady_factor();
+    return static_cast<steady_clock::rep>(mach_absolute_time() * factor);
+}
+
+typedef steady_clock::rep (*FP)();
+
+static
+FP
+init_steady_clock()
+{
+    mach_timebase_info_data_t MachInfo;
+    mach_timebase_info(&MachInfo);
+    if (MachInfo.numer == MachInfo.denom)
+        return &steady_simplified;
+    return &steady_full;
+}
+
+steady_clock::time_point
+steady_clock::now() _NOEXCEPT
+{
+    static FP fp = init_steady_clock();
+    return time_point(duration(fp()));
+}
+#endif // defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_UPTIME_RAW)
+
+#elif defined(_LIBCPP_WIN32API)
+
+// https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says:
+//    If the function fails, the return value is zero. <snip>
+//    On systems that run Windows XP or later, the function will always succeed
+//      and will thus never return zero.
+
+static LARGE_INTEGER
+__QueryPerformanceFrequency()
+{
+	LARGE_INTEGER val;
+	(void) QueryPerformanceFrequency(&val);
+	return val;
+}
+
+steady_clock::time_point
+steady_clock::now() _NOEXCEPT
+{
+  static const LARGE_INTEGER freq = __QueryPerformanceFrequency();
+
+  LARGE_INTEGER counter;
+  (void) QueryPerformanceCounter(&counter);
+  return time_point(duration(counter.QuadPart * nano::den / freq.QuadPart));
+}
+
+#elif defined(CLOCK_MONOTONIC)
+
+// On Apple platforms only CLOCK_UPTIME_RAW or mach_absolute_time are able to
+// time functions in the nanosecond range. Thus, they are the only acceptable
+// implementations of steady_clock.
+#ifdef __APPLE__
+#error "Never use CLOCK_MONOTONIC for steady_clock::now on Apple platforms"
+#endif
+
+steady_clock::time_point
+steady_clock::now() _NOEXCEPT
+{
+    struct timespec tp;
+    if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
+        __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
+    return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
+}
+
+#else
+#error "Monotonic clock not implemented"
+#endif
+
+#endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK
+
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/condition_variable.cpp b/lib/libcxx/src/condition_variable.cpp
new file mode 100644
index 0000000000..d133b010d7
--- /dev/null
+++ b/lib/libcxx/src/condition_variable.cpp
@@ -0,0 +1,93 @@
+//===-------------------- condition_variable.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include "condition_variable"
+#include "thread"
+#include "system_error"
+#include "__undef_macros"
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// ~condition_variable is defined elsewhere.
+
+void
+condition_variable::notify_one() _NOEXCEPT
+{
+    __libcpp_condvar_signal(&__cv_);
+}
+
+void
+condition_variable::notify_all() _NOEXCEPT
+{
+    __libcpp_condvar_broadcast(&__cv_);
+}
+
+void
+condition_variable::wait(unique_lock<mutex>& lk) _NOEXCEPT
+{
+    if (!lk.owns_lock())
+        __throw_system_error(EPERM,
+                                  "condition_variable::wait: mutex not locked");
+    int ec = __libcpp_condvar_wait(&__cv_, lk.mutex()->native_handle());
+    if (ec)
+        __throw_system_error(ec, "condition_variable wait failed");
+}
+
+void
+condition_variable::__do_timed_wait(unique_lock<mutex>& lk,
+     chrono::time_point<chrono::system_clock, chrono::nanoseconds> tp) _NOEXCEPT
+{
+    using namespace chrono;
+    if (!lk.owns_lock())
+        __throw_system_error(EPERM,
+                            "condition_variable::timed wait: mutex not locked");
+    nanoseconds d = tp.time_since_epoch();
+    if (d > nanoseconds(0x59682F000000E941))
+        d = nanoseconds(0x59682F000000E941);
+    __libcpp_timespec_t ts;
+    seconds s = duration_cast<seconds>(d);
+    typedef decltype(ts.tv_sec) ts_sec;
+    _LIBCPP_CONSTEXPR ts_sec ts_sec_max = numeric_limits<ts_sec>::max();
+    if (s.count() < ts_sec_max)
+    {
+        ts.tv_sec = static_cast<ts_sec>(s.count());
+        ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((d - s).count());
+    }
+    else
+    {
+        ts.tv_sec = ts_sec_max;
+        ts.tv_nsec = giga::num - 1;
+    }
+    int ec = __libcpp_condvar_timedwait(&__cv_, lk.mutex()->native_handle(), &ts);
+    if (ec != 0 && ec != ETIMEDOUT)
+        __throw_system_error(ec, "condition_variable timed_wait failed");
+}
+
+void
+notify_all_at_thread_exit(condition_variable& cond, unique_lock<mutex> lk)
+{
+    auto& tl_ptr = __thread_local_data();
+    // If this thread was not created using std::thread then it will not have
+    // previously allocated.
+    if (tl_ptr.get() == nullptr) {
+        tl_ptr.set_pointer(new __thread_struct);
+    }
+    __thread_local_data()->notify_all_at_thread_exit(&cond, lk.release());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS
diff --git a/lib/libcxx/src/condition_variable_destructor.cpp b/lib/libcxx/src/condition_variable_destructor.cpp
new file mode 100644
index 0000000000..44fa240ba7
--- /dev/null
+++ b/lib/libcxx/src/condition_variable_destructor.cpp
@@ -0,0 +1,46 @@
+//===---------------- condition_variable_destructor.cpp ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Define ~condition_variable.
+//
+// On some platforms ~condition_variable has been made trivial and the
+// definition is only provided for ABI compatibility.
+
+#include "__config"
+#include "__threading_support"
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+# if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION)
+#   define NEEDS_CONDVAR_DESTRUCTOR
+# endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef NEEDS_CONDVAR_DESTRUCTOR
+
+class _LIBCPP_TYPE_VIS condition_variable
+{
+    __libcpp_condvar_t __cv_ = _LIBCPP_CONDVAR_INITIALIZER;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr condition_variable() noexcept = default;
+
+    ~condition_variable();
+
+    condition_variable(const condition_variable&) = delete;
+    condition_variable& operator=(const condition_variable&)  = delete;
+};
+
+condition_variable::~condition_variable()
+{
+    __libcpp_condvar_destroy(&__cv_);
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/debug.cpp b/lib/libcxx/src/debug.cpp
new file mode 100644
index 0000000000..20055fcf75
--- /dev/null
+++ b/lib/libcxx/src/debug.cpp
@@ -0,0 +1,578 @@
+//===-------------------------- debug.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+#include "__debug"
+#include "functional"
+#include "algorithm"
+#include "string"
+#include "cstdio"
+#include "__hash_table"
+#ifndef _LIBCPP_HAS_NO_THREADS
+#include "mutex"
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+std::string __libcpp_debug_info::what() const {
+  string msg = __file_;
+  msg += ":" + to_string(__line_) + ": _LIBCPP_ASSERT '";
+  msg += __pred_;
+  msg += "' failed. ";
+  msg += __msg_;
+  return msg;
+}
+_LIBCPP_NORETURN void __libcpp_abort_debug_function(__libcpp_debug_info const& info) {
+    std::fprintf(stderr, "%s\n", info.what().c_str());
+    std::abort();
+}
+
+_LIBCPP_SAFE_STATIC __libcpp_debug_function_type
+    __libcpp_debug_function = __libcpp_abort_debug_function;
+
+bool __libcpp_set_debug_function(__libcpp_debug_function_type __func) {
+  __libcpp_debug_function = __func;
+  return true;
+}
+
+_LIBCPP_FUNC_VIS
+__libcpp_db*
+__get_db()
+{
+    static _LIBCPP_NO_DESTROY __libcpp_db db;
+    return &db;
+}
+
+_LIBCPP_FUNC_VIS
+const __libcpp_db*
+__get_const_db()
+{
+    return __get_db();
+}
+
+namespace
+{
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+typedef mutex mutex_type;
+typedef lock_guard<mutex_type> WLock;
+typedef lock_guard<mutex_type> RLock;
+
+mutex_type&
+mut()
+{
+    static _LIBCPP_NO_DESTROY mutex_type m;
+    return m;
+}
+#endif // !_LIBCPP_HAS_NO_THREADS
+
+}  // unnamed namespace
+
+__i_node::~__i_node()
+{
+    if (__next_)
+    {
+        __next_->~__i_node();
+        free(__next_);
+    }
+}
+
+__c_node::~__c_node()
+{
+    free(beg_);
+    if (__next_)
+    {
+        __next_->~__c_node();
+        free(__next_);
+    }
+}
+
+__libcpp_db::__libcpp_db()
+    : __cbeg_(nullptr),
+      __cend_(nullptr),
+      __csz_(0),
+      __ibeg_(nullptr),
+      __iend_(nullptr),
+      __isz_(0)
+{
+}
+
+__libcpp_db::~__libcpp_db()
+{
+    if (__cbeg_)
+    {
+        for (__c_node** p = __cbeg_; p != __cend_; ++p)
+        {
+            if (*p != nullptr)
+            {
+                (*p)->~__c_node();
+                free(*p);
+            }
+        }
+        free(__cbeg_);
+    }
+    if (__ibeg_)
+    {
+        for (__i_node** p = __ibeg_; p != __iend_; ++p)
+        {
+            if (*p != nullptr)
+            {
+                (*p)->~__i_node();
+                free(*p);
+            }
+        }
+        free(__ibeg_);
+    }
+}
+
+void*
+__libcpp_db::__find_c_from_i(void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    _LIBCPP_ASSERT(i != nullptr, "iterator not found in debug database.");
+    return i->__c_ != nullptr ? i->__c_->__c_ : nullptr;
+}
+
+void
+__libcpp_db::__insert_ic(void* __i, const void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cbeg_ == __cend_)
+        return;
+    size_t hc = hash<const void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* c = __cbeg_[hc];
+    if (c == nullptr)
+        return;
+    while (c->__c_ != __c)
+    {
+        c = c->__next_;
+        if (c == nullptr)
+            return;
+    }
+    __i_node* i = __insert_iterator(__i);
+    c->__add(i);
+    i->__c_ = c;
+}
+
+void
+__libcpp_db::__insert_c(void* __c, __libcpp_db::_InsertConstruct *__fn)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__csz_ + 1 > static_cast<size_t>(__cend_ - __cbeg_))
+    {
+        size_t nc = __next_prime(2*static_cast<size_t>(__cend_ - __cbeg_) + 1);
+        __c_node** cbeg = static_cast<__c_node**>(calloc(nc, sizeof(__c_node*)));
+        if (cbeg == nullptr)
+            __throw_bad_alloc();
+
+        for (__c_node** p = __cbeg_; p != __cend_; ++p)
+        {
+            __c_node* q = *p;
+            while (q != nullptr)
+            {
+                size_t h = hash<void*>()(q->__c_) % nc;
+                __c_node* r = q->__next_;
+                q->__next_ = cbeg[h];
+                cbeg[h] = q;
+                q = r;
+            }
+        }
+        free(__cbeg_);
+        __cbeg_ = cbeg;
+        __cend_ = __cbeg_ + nc;
+    }
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    void *buf = malloc(sizeof(__c_node));
+    if (buf == nullptr)
+      __throw_bad_alloc();
+    __cbeg_[hc] = __fn(buf, __c, p);
+
+    ++__csz_;
+}
+
+void
+__libcpp_db::__erase_i(void* __i)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__ibeg_ != __iend_)
+    {
+        size_t hi = hash<void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+        __i_node* p = __ibeg_[hi];
+        if (p != nullptr)
+        {
+            __i_node* q = nullptr;
+            while (p->__i_ != __i)
+            {
+                q = p;
+                p = p->__next_;
+                if (p == nullptr)
+                    return;
+            }
+            if (q == nullptr)
+                __ibeg_[hi] = p->__next_;
+            else
+                q->__next_ = p->__next_;
+            __c_node* c = p->__c_;
+            --__isz_;
+            if (c != nullptr)
+                c->__remove(p);
+            free(p);
+        }
+    }
+}
+
+void
+__libcpp_db::__invalidate_all(void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cend_ != __cbeg_)
+    {
+        size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+        __c_node* p = __cbeg_[hc];
+        if (p == nullptr)
+            return;
+        while (p->__c_ != __c)
+        {
+            p = p->__next_;
+            if (p == nullptr)
+                return;
+        }
+        while (p->end_ != p->beg_)
+        {
+            --p->end_;
+            (*p->end_)->__c_ = nullptr;
+        }
+    }
+}
+
+__c_node*
+__libcpp_db::__find_c_and_lock(void* __c) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    mut().lock();
+#endif
+    if (__cend_ == __cbeg_)
+    {
+#ifndef _LIBCPP_HAS_NO_THREADS
+        mut().unlock();
+#endif
+        return nullptr;
+    }
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    if (p == nullptr)
+    {
+#ifndef _LIBCPP_HAS_NO_THREADS
+        mut().unlock();
+#endif
+        return nullptr;
+    }
+    while (p->__c_ != __c)
+    {
+        p = p->__next_;
+        if (p == nullptr)
+        {
+#ifndef _LIBCPP_HAS_NO_THREADS
+            mut().unlock();
+#endif
+            return nullptr;
+        }
+    }
+    return p;
+}
+
+__c_node*
+__libcpp_db::__find_c(void* __c) const
+{
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __find_c A");
+    while (p->__c_ != __c)
+    {
+        p = p->__next_;
+        _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __find_c B");
+    }
+    return p;
+}
+
+void
+__libcpp_db::unlock() const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    mut().unlock();
+#endif
+}
+
+void
+__libcpp_db::__erase_c(void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cend_ != __cbeg_)
+    {
+        size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+        __c_node* p = __cbeg_[hc];
+        if (p == nullptr)
+            return;
+        __c_node* q = nullptr;
+        _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __erase_c A");
+        while (p->__c_ != __c)
+        {
+            q = p;
+            p = p->__next_;
+            if (p == nullptr)
+                return;
+            _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __erase_c B");
+        }
+        if (q == nullptr)
+            __cbeg_[hc] = p->__next_;
+        else
+            q->__next_ = p->__next_;
+        while (p->end_ != p->beg_)
+        {
+            --p->end_;
+            (*p->end_)->__c_ = nullptr;
+        }
+        free(p->beg_);
+        free(p);
+        --__csz_;
+    }
+}
+
+void
+__libcpp_db::__iterator_copy(void* __i, const void* __i0)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    __i_node* i0 = __find_iterator(__i0);
+    __c_node* c0 = i0 != nullptr ? i0->__c_ : nullptr;
+    if (i == nullptr && i0 != nullptr)
+        i = __insert_iterator(__i);
+    __c_node* c = i != nullptr ? i->__c_ : nullptr;
+    if (c != c0)
+    {
+        if (c != nullptr)
+            c->__remove(i);
+        if (i != nullptr)
+        {
+            i->__c_ = nullptr;
+            if (c0 != nullptr)
+            {
+                i->__c_ = c0;
+                i->__c_->__add(i);
+            }
+        }
+    }
+}
+
+bool
+__libcpp_db::__dereferenceable(const void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__dereferenceable(__i);
+}
+
+bool
+__libcpp_db::__decrementable(const void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__decrementable(__i);
+}
+
+bool
+__libcpp_db::__addable(const void* __i, ptrdiff_t __n) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__addable(__i, __n);
+}
+
+bool
+__libcpp_db::__subscriptable(const void* __i, ptrdiff_t __n) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__subscriptable(__i, __n);
+}
+
+bool
+__libcpp_db::__less_than_comparable(const void* __i, const void* __j) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    __i_node* j = __find_iterator(__j);
+    __c_node* ci = i != nullptr ? i->__c_ : nullptr;
+    __c_node* cj = j != nullptr ? j->__c_ : nullptr;
+    return ci != nullptr && ci == cj;
+}
+
+void
+__libcpp_db::swap(void* c1, void* c2)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    size_t hc = hash<void*>()(c1) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p1 = __cbeg_[hc];
+    _LIBCPP_ASSERT(p1 != nullptr, "debug mode internal logic error swap A");
+    while (p1->__c_ != c1)
+    {
+        p1 = p1->__next_;
+        _LIBCPP_ASSERT(p1 != nullptr, "debug mode internal logic error swap B");
+    }
+    hc = hash<void*>()(c2) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p2 = __cbeg_[hc];
+    _LIBCPP_ASSERT(p2 != nullptr, "debug mode internal logic error swap C");
+    while (p2->__c_ != c2)
+    {
+        p2 = p2->__next_;
+        _LIBCPP_ASSERT(p2 != nullptr, "debug mode internal logic error swap D");
+    }
+    std::swap(p1->beg_, p2->beg_);
+    std::swap(p1->end_, p2->end_);
+    std::swap(p1->cap_, p2->cap_);
+    for (__i_node** p = p1->beg_; p != p1->end_; ++p)
+        (*p)->__c_ = p1;
+    for (__i_node** p = p2->beg_; p != p2->end_; ++p)
+        (*p)->__c_ = p2;
+}
+
+void
+__libcpp_db::__insert_i(void* __i)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    __insert_iterator(__i);
+}
+
+void
+__c_node::__add(__i_node* i)
+{
+    if (end_ == cap_)
+    {
+        size_t nc = 2*static_cast<size_t>(cap_ - beg_);
+        if (nc == 0)
+            nc = 1;
+        __i_node** beg =
+           static_cast<__i_node**>(malloc(nc * sizeof(__i_node*)));
+        if (beg == nullptr)
+            __throw_bad_alloc();
+
+        if (nc > 1)
+            memcpy(beg, beg_, nc/2*sizeof(__i_node*));
+        free(beg_);
+        beg_ = beg;
+        end_ = beg_ + nc/2;
+        cap_ = beg_ + nc;
+    }
+    *end_++ = i;
+}
+
+// private api
+
+_LIBCPP_HIDDEN
+__i_node*
+__libcpp_db::__insert_iterator(void* __i)
+{
+    if (__isz_ + 1 > static_cast<size_t>(__iend_ - __ibeg_))
+    {
+        size_t nc = __next_prime(2*static_cast<size_t>(__iend_ - __ibeg_) + 1);
+        __i_node** ibeg = static_cast<__i_node**>(calloc(nc, sizeof(__i_node*)));
+        if (ibeg == nullptr)
+            __throw_bad_alloc();
+
+        for (__i_node** p = __ibeg_; p != __iend_; ++p)
+        {
+            __i_node* q = *p;
+            while (q != nullptr)
+            {
+                size_t h = hash<void*>()(q->__i_) % nc;
+                __i_node* r = q->__next_;
+                q->__next_ = ibeg[h];
+                ibeg[h] = q;
+                q = r;
+            }
+        }
+        free(__ibeg_);
+        __ibeg_ = ibeg;
+        __iend_ = __ibeg_ + nc;
+    }
+    size_t hi = hash<void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+    __i_node* p = __ibeg_[hi];
+    __i_node* r = __ibeg_[hi] =
+      static_cast<__i_node*>(malloc(sizeof(__i_node)));
+    if (r == nullptr)
+        __throw_bad_alloc();
+
+    ::new(r) __i_node(__i, p, nullptr);
+    ++__isz_;
+    return r;
+}
+
+_LIBCPP_HIDDEN
+__i_node*
+__libcpp_db::__find_iterator(const void* __i) const
+{
+    __i_node* r = nullptr;
+    if (__ibeg_ != __iend_)
+    {
+        size_t h = hash<const void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+        for (__i_node* nd = __ibeg_[h]; nd != nullptr; nd = nd->__next_)
+        {
+            if (nd->__i_ == __i)
+            {
+                r = nd;
+                break;
+            }
+        }
+    }
+    return r;
+}
+
+_LIBCPP_HIDDEN
+void
+__c_node::__remove(__i_node* p)
+{
+    __i_node** r = find(beg_, end_, p);
+    _LIBCPP_ASSERT(r != end_, "debug mode internal logic error __c_node::__remove");
+    if (--end_ != r)
+        memmove(r, r+1, static_cast<size_t>(end_ - r)*sizeof(__i_node*));
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/exception.cpp b/lib/libcxx/src/exception.cpp
new file mode 100644
index 0000000000..fce6db7c38
--- /dev/null
+++ b/lib/libcxx/src/exception.cpp
@@ -0,0 +1,35 @@
+//===------------------------ exception.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "exception"
+#include "new"
+#include "typeinfo"
+
+#if defined(LIBCXXRT) || defined(LIBCXX_BUILDING_LIBCXXABI)
+  #include <cxxabi.h>
+  using namespace __cxxabiv1;
+  #define HAVE_DEPENDENT_EH_ABI 1
+#endif
+
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#include "support/runtime/exception_msvc.ipp"
+#include "support/runtime/exception_pointer_msvc.ipp"
+#elif defined(_LIBCPPABI_VERSION)
+#include "support/runtime/exception_libcxxabi.ipp"
+#include "support/runtime/exception_pointer_cxxabi.ipp"
+#elif defined(LIBCXXRT)
+#include "support/runtime/exception_libcxxrt.ipp"
+#include "support/runtime/exception_pointer_cxxabi.ipp"
+#elif defined(__GLIBCXX__)
+#include "support/runtime/exception_glibcxx.ipp"
+#include "support/runtime/exception_pointer_glibcxx.ipp"
+#else
+#include "include/atomic_support.h"
+#include "support/runtime/exception_fallback.ipp"
+#include "support/runtime/exception_pointer_unimplemented.ipp"
+#endif
diff --git a/lib/libcxx/src/experimental/memory_resource.cpp b/lib/libcxx/src/experimental/memory_resource.cpp
new file mode 100644
index 0000000000..68c5bc99cc
--- /dev/null
+++ b/lib/libcxx/src/experimental/memory_resource.cpp
@@ -0,0 +1,161 @@
+//===------------------------ memory_resource.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "experimental/memory_resource"
+
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+#include "atomic"
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+#include "mutex"
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
+
+// memory_resource
+
+//memory_resource::~memory_resource() {}
+
+// new_delete_resource()
+
+class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
+    : public memory_resource
+{
+    void *do_allocate(size_t size, size_t align) override {
+#ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
+        if (__is_overaligned_for_new(align))
+            __throw_bad_alloc();
+#endif
+        return _VSTD::__libcpp_allocate(size, align);
+    }
+
+    void do_deallocate(void *p, size_t n, size_t align) override {
+      _VSTD::__libcpp_deallocate(p, n, align);
+    }
+
+    bool do_is_equal(memory_resource const & other) const _NOEXCEPT override
+        { return &other == this; }
+
+public:
+    ~__new_delete_memory_resource_imp() override = default;
+};
+
+// null_memory_resource()
+
+class _LIBCPP_TYPE_VIS __null_memory_resource_imp
+    : public memory_resource
+{
+public:
+    ~__null_memory_resource_imp() = default;
+
+protected:
+    virtual void* do_allocate(size_t, size_t) {
+        __throw_bad_alloc();
+    }
+    virtual void do_deallocate(void *, size_t, size_t) {}
+    virtual bool do_is_equal(memory_resource const & __other) const _NOEXCEPT
+    { return &__other == this; }
+};
+
+namespace {
+
+union ResourceInitHelper {
+  struct {
+    __new_delete_memory_resource_imp new_delete_res;
+    __null_memory_resource_imp       null_res;
+  } resources;
+  char dummy;
+  _LIBCPP_CONSTEXPR_AFTER_CXX11 ResourceInitHelper() : resources() {}
+  ~ResourceInitHelper() {}
+};
+
+// Detect if the init_priority attribute is supported.
+#if (defined(_LIBCPP_COMPILER_GCC) && defined(__APPLE__)) \
+  || defined(_LIBCPP_COMPILER_MSVC)
+// GCC on Apple doesn't support the init priority attribute,
+// and MSVC doesn't support any GCC attributes.
+# define _LIBCPP_INIT_PRIORITY_MAX
+#else
+# define _LIBCPP_INIT_PRIORITY_MAX __attribute__((init_priority(101)))
+#endif
+
+// When compiled in C++14 this initialization should be a constant expression.
+// Only in C++11 is "init_priority" needed to ensure initialization order.
+#if _LIBCPP_STD_VER > 11
+_LIBCPP_SAFE_STATIC
+#endif
+ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;
+
+} // end namespace
+
+
+memory_resource * new_delete_resource() _NOEXCEPT {
+    return &res_init.resources.new_delete_res;
+}
+
+memory_resource * null_memory_resource() _NOEXCEPT {
+    return &res_init.resources.null_res;
+}
+
+// default_memory_resource()
+
+static memory_resource *
+__default_memory_resource(bool set = false, memory_resource * new_res = nullptr) _NOEXCEPT
+{
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+    _LIBCPP_SAFE_STATIC static atomic<memory_resource*> __res =
+        ATOMIC_VAR_INIT(&res_init.resources.new_delete_res);
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        // TODO: Can a weaker ordering be used?
+        return _VSTD::atomic_exchange_explicit(
+            &__res, new_res, memory_order_acq_rel);
+    }
+    else {
+        return _VSTD::atomic_load_explicit(
+            &__res, memory_order_acquire);
+    }
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+    _LIBCPP_SAFE_STATIC static memory_resource * res = &res_init.resources.new_delete_res;
+    static mutex res_lock;
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        lock_guard<mutex> guard(res_lock);
+        memory_resource * old_res = res;
+        res = new_res;
+        return old_res;
+    } else {
+        lock_guard<mutex> guard(res_lock);
+        return res;
+    }
+#else
+    _LIBCPP_SAFE_STATIC static memory_resource* res = &res_init.resources.new_delete_res;
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        memory_resource * old_res = res;
+        res = new_res;
+        return old_res;
+    } else {
+        return res;
+    }
+#endif
+}
+
+memory_resource * get_default_resource() _NOEXCEPT
+{
+    return __default_memory_resource();
+}
+
+memory_resource * set_default_resource(memory_resource * __new_res) _NOEXCEPT
+{
+    return __default_memory_resource(true, __new_res);
+}
+
+_LIBCPP_END_NAMESPACE_LFTS_PMR
diff --git a/lib/libcxx/src/filesystem/directory_iterator.cpp b/lib/libcxx/src/filesystem/directory_iterator.cpp
new file mode 100644
index 0000000000..e8941b3494
--- /dev/null
+++ b/lib/libcxx/src/filesystem/directory_iterator.cpp
@@ -0,0 +1,398 @@
+//===------------------ directory_iterator.cpp ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "filesystem"
+#include "__config"
+#if defined(_LIBCPP_WIN32API)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else
+#include <dirent.h>
+#endif
+#include <errno.h>
+
+#include "filesystem_common.h"
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+namespace detail {
+namespace {
+
+#if !defined(_LIBCPP_WIN32API)
+
+#if defined(DT_BLK)
+template <class DirEntT, class = decltype(DirEntT::d_type)>
+static file_type get_file_type(DirEntT* ent, int) {
+  switch (ent->d_type) {
+  case DT_BLK:
+    return file_type::block;
+  case DT_CHR:
+    return file_type::character;
+  case DT_DIR:
+    return file_type::directory;
+  case DT_FIFO:
+    return file_type::fifo;
+  case DT_LNK:
+    return file_type::symlink;
+  case DT_REG:
+    return file_type::regular;
+  case DT_SOCK:
+    return file_type::socket;
+  // Unlike in lstat, hitting "unknown" here simply means that the underlying
+  // filesystem doesn't support d_type. Report is as 'none' so we correctly
+  // set the cache to empty.
+  case DT_UNKNOWN:
+    break;
+  }
+  return file_type::none;
+}
+#endif // defined(DT_BLK)
+
+template <class DirEntT>
+static file_type get_file_type(DirEntT* ent, long) {
+  return file_type::none;
+}
+
+static pair<string_view, file_type> posix_readdir(DIR* dir_stream,
+                                                  error_code& ec) {
+  struct dirent* dir_entry_ptr = nullptr;
+  errno = 0; // zero errno in order to detect errors
+  ec.clear();
+  if ((dir_entry_ptr = ::readdir(dir_stream)) == nullptr) {
+    if (errno)
+      ec = capture_errno();
+    return {};
+  } else {
+    return {dir_entry_ptr->d_name, get_file_type(dir_entry_ptr, 0)};
+  }
+}
+#else
+
+static file_type get_file_type(const WIN32_FIND_DATA& data) {
+  //auto attrs = data.dwFileAttributes;
+  // FIXME(EricWF)
+  return file_type::unknown;
+}
+static uintmax_t get_file_size(const WIN32_FIND_DATA& data) {
+  return (data.nFileSizeHigh * (MAXDWORD + 1)) + data.nFileSizeLow;
+}
+static file_time_type get_write_time(const WIN32_FIND_DATA& data) {
+  ULARGE_INTEGER tmp;
+  const FILETIME& time = data.ftLastWriteTime;
+  tmp.u.LowPart = time.dwLowDateTime;
+  tmp.u.HighPart = time.dwHighDateTime;
+  return file_time_type(file_time_type::duration(tmp.QuadPart));
+}
+
+#endif
+
+} // namespace
+} // namespace detail
+
+using detail::ErrorHandler;
+
+#if defined(_LIBCPP_WIN32API)
+class __dir_stream {
+public:
+  __dir_stream() = delete;
+  __dir_stream& operator=(const __dir_stream&) = delete;
+
+  __dir_stream(__dir_stream&& __ds) noexcept : __stream_(__ds.__stream_),
+                                               __root_(move(__ds.__root_)),
+                                               __entry_(move(__ds.__entry_)) {
+    __ds.__stream_ = INVALID_HANDLE_VALUE;
+  }
+
+  __dir_stream(const path& root, directory_options opts, error_code& ec)
+      : __stream_(INVALID_HANDLE_VALUE), __root_(root) {
+    __stream_ = ::FindFirstFile(root.c_str(), &__data_);
+    if (__stream_ == INVALID_HANDLE_VALUE) {
+      ec = error_code(::GetLastError(), generic_category());
+      const bool ignore_permission_denied =
+          bool(opts & directory_options::skip_permission_denied);
+      if (ignore_permission_denied && ec.value() == ERROR_ACCESS_DENIED)
+        ec.clear();
+      return;
+    }
+  }
+
+  ~__dir_stream() noexcept {
+    if (__stream_ == INVALID_HANDLE_VALUE)
+      return;
+    close();
+  }
+
+  bool good() const noexcept { return __stream_ != INVALID_HANDLE_VALUE; }
+
+  bool advance(error_code& ec) {
+    while (::FindNextFile(__stream_, &__data_)) {
+      if (!strcmp(__data_.cFileName, ".") || strcmp(__data_.cFileName, ".."))
+        continue;
+      // FIXME: Cache more of this
+      //directory_entry::__cached_data cdata;
+      //cdata.__type_ = get_file_type(__data_);
+      //cdata.__size_ = get_file_size(__data_);
+      //cdata.__write_time_ = get_write_time(__data_);
+      __entry_.__assign_iter_entry(
+          __root_ / __data_.cFileName,
+          directory_entry::__create_iter_result(detail::get_file_type(__data)));
+      return true;
+    }
+    ec = error_code(::GetLastError(), generic_category());
+    close();
+    return false;
+  }
+
+private:
+  error_code close() noexcept {
+    error_code ec;
+    if (!::FindClose(__stream_))
+      ec = error_code(::GetLastError(), generic_category());
+    __stream_ = INVALID_HANDLE_VALUE;
+    return ec;
+  }
+
+  HANDLE __stream_{INVALID_HANDLE_VALUE};
+  WIN32_FIND_DATA __data_;
+
+public:
+  path __root_;
+  directory_entry __entry_;
+};
+#else
+class __dir_stream {
+public:
+  __dir_stream() = delete;
+  __dir_stream& operator=(const __dir_stream&) = delete;
+
+  __dir_stream(__dir_stream&& other) noexcept : __stream_(other.__stream_),
+                                                __root_(move(other.__root_)),
+                                                __entry_(move(other.__entry_)) {
+    other.__stream_ = nullptr;
+  }
+
+  __dir_stream(const path& root, directory_options opts, error_code& ec)
+      : __stream_(nullptr), __root_(root) {
+    if ((__stream_ = ::opendir(root.c_str())) == nullptr) {
+      ec = detail::capture_errno();
+      const bool allow_eacess =
+          bool(opts & directory_options::skip_permission_denied);
+      if (allow_eacess && ec.value() == EACCES)
+        ec.clear();
+      return;
+    }
+    advance(ec);
+  }
+
+  ~__dir_stream() noexcept {
+    if (__stream_)
+      close();
+  }
+
+  bool good() const noexcept { return __stream_ != nullptr; }
+
+  bool advance(error_code& ec) {
+    while (true) {
+      auto str_type_pair = detail::posix_readdir(__stream_, ec);
+      auto& str = str_type_pair.first;
+      if (str == "." || str == "..") {
+        continue;
+      } else if (ec || str.empty()) {
+        close();
+        return false;
+      } else {
+        __entry_.__assign_iter_entry(
+            __root_ / str,
+            directory_entry::__create_iter_result(str_type_pair.second));
+        return true;
+      }
+    }
+  }
+
+private:
+  error_code close() noexcept {
+    error_code m_ec;
+    if (::closedir(__stream_) == -1)
+      m_ec = detail::capture_errno();
+    __stream_ = nullptr;
+    return m_ec;
+  }
+
+  DIR* __stream_{nullptr};
+
+public:
+  path __root_;
+  directory_entry __entry_;
+};
+#endif
+
+// directory_iterator
+
+directory_iterator::directory_iterator(const path& p, error_code* ec,
+                                       directory_options opts) {
+  ErrorHandler<void> err("directory_iterator::directory_iterator(...)", ec, &p);
+
+  error_code m_ec;
+  __imp_ = make_shared<__dir_stream>(p, opts, m_ec);
+  if (ec)
+    *ec = m_ec;
+  if (!__imp_->good()) {
+    __imp_.reset();
+    if (m_ec)
+      err.report(m_ec);
+  }
+}
+
+directory_iterator& directory_iterator::__increment(error_code* ec) {
+  _LIBCPP_ASSERT(__imp_, "Attempting to increment an invalid iterator");
+  ErrorHandler<void> err("directory_iterator::operator++()", ec);
+
+  error_code m_ec;
+  if (!__imp_->advance(m_ec)) {
+    path root = move(__imp_->__root_);
+    __imp_.reset();
+    if (m_ec)
+      err.report(m_ec, "at root \"%s\"", root);
+  }
+  return *this;
+}
+
+directory_entry const& directory_iterator::__dereference() const {
+  _LIBCPP_ASSERT(__imp_, "Attempting to dereference an invalid iterator");
+  return __imp_->__entry_;
+}
+
+// recursive_directory_iterator
+
+struct recursive_directory_iterator::__shared_imp {
+  stack<__dir_stream> __stack_;
+  directory_options __options_;
+};
+
+recursive_directory_iterator::recursive_directory_iterator(
+    const path& p, directory_options opt, error_code* ec)
+    : __imp_(nullptr), __rec_(true) {
+  ErrorHandler<void> err("recursive_directory_iterator", ec, &p);
+
+  error_code m_ec;
+  __dir_stream new_s(p, opt, m_ec);
+  if (m_ec)
+    err.report(m_ec);
+  if (m_ec || !new_s.good())
+    return;
+
+  __imp_ = make_shared<__shared_imp>();
+  __imp_->__options_ = opt;
+  __imp_->__stack_.push(move(new_s));
+}
+
+void recursive_directory_iterator::__pop(error_code* ec) {
+  _LIBCPP_ASSERT(__imp_, "Popping the end iterator");
+  if (ec)
+    ec->clear();
+  __imp_->__stack_.pop();
+  if (__imp_->__stack_.size() == 0)
+    __imp_.reset();
+  else
+    __advance(ec);
+}
+
+directory_options recursive_directory_iterator::options() const {
+  return __imp_->__options_;
+}
+
+int recursive_directory_iterator::depth() const {
+  return __imp_->__stack_.size() - 1;
+}
+
+const directory_entry& recursive_directory_iterator::__dereference() const {
+  return __imp_->__stack_.top().__entry_;
+}
+
+recursive_directory_iterator&
+recursive_directory_iterator::__increment(error_code* ec) {
+  if (ec)
+    ec->clear();
+  if (recursion_pending()) {
+    if (__try_recursion(ec) || (ec && *ec))
+      return *this;
+  }
+  __rec_ = true;
+  __advance(ec);
+  return *this;
+}
+
+void recursive_directory_iterator::__advance(error_code* ec) {
+  ErrorHandler<void> err("recursive_directory_iterator::operator++()", ec);
+
+  const directory_iterator end_it;
+  auto& stack = __imp_->__stack_;
+  error_code m_ec;
+  while (stack.size() > 0) {
+    if (stack.top().advance(m_ec))
+      return;
+    if (m_ec)
+      break;
+    stack.pop();
+  }
+
+  if (m_ec) {
+    path root = move(stack.top().__root_);
+    __imp_.reset();
+    err.report(m_ec, "at root \"%s\"", root);
+  } else {
+    __imp_.reset();
+  }
+}
+
+bool recursive_directory_iterator::__try_recursion(error_code* ec) {
+  ErrorHandler<void> err("recursive_directory_iterator::operator++()", ec);
+
+  bool rec_sym = bool(options() & directory_options::follow_directory_symlink);
+
+  auto& curr_it = __imp_->__stack_.top();
+
+  bool skip_rec = false;
+  error_code m_ec;
+  if (!rec_sym) {
+    file_status st(curr_it.__entry_.__get_sym_ft(&m_ec));
+    if (m_ec && status_known(st))
+      m_ec.clear();
+    if (m_ec || is_symlink(st) || !is_directory(st))
+      skip_rec = true;
+  } else {
+    file_status st(curr_it.__entry_.__get_ft(&m_ec));
+    if (m_ec && status_known(st))
+      m_ec.clear();
+    if (m_ec || !is_directory(st))
+      skip_rec = true;
+  }
+
+  if (!skip_rec) {
+    __dir_stream new_it(curr_it.__entry_.path(), __imp_->__options_, m_ec);
+    if (new_it.good()) {
+      __imp_->__stack_.push(move(new_it));
+      return true;
+    }
+  }
+  if (m_ec) {
+    const bool allow_eacess =
+        bool(__imp_->__options_ & directory_options::skip_permission_denied);
+    if (m_ec.value() == EACCES && allow_eacess) {
+      if (ec)
+        ec->clear();
+    } else {
+      path at_ent = move(curr_it.__entry_.__p_);
+      __imp_.reset();
+      err.report(m_ec, "attempting recursion into \"%s\"", at_ent);
+    }
+  }
+  return false;
+}
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM
diff --git a/lib/libcxx/src/filesystem/filesystem_common.h b/lib/libcxx/src/filesystem/filesystem_common.h
new file mode 100644
index 0000000000..fe5c42f5e6
--- /dev/null
+++ b/lib/libcxx/src/filesystem/filesystem_common.h
@@ -0,0 +1,435 @@
+//===----------------------------------------------------------------------===////
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===////
+
+#ifndef FILESYSTEM_COMMON_H
+#define FILESYSTEM_COMMON_H
+
+#include "__config"
+#include "filesystem"
+#include "array"
+#include "chrono"
+#include "cstdlib"
+#include "climits"
+
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/time.h> // for ::utimes as used in __last_write_time
+#include <fcntl.h>    /* values for fchmodat */
+
+#include "../include/apple_availability.h"
+
+#if !defined(__APPLE__)
+// We can use the presence of UTIME_OMIT to detect platforms that provide
+// utimensat.
+#if defined(UTIME_OMIT)
+#define _LIBCPP_USE_UTIMENSAT
+#endif
+#endif
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-function"
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+namespace detail {
+namespace {
+
+static string format_string_imp(const char* msg, ...) {
+  // we might need a second shot at this, so pre-emptivly make a copy
+  struct GuardVAList {
+    va_list& target;
+    bool active = true;
+    GuardVAList(va_list& target) : target(target), active(true) {}
+    void clear() {
+      if (active)
+        va_end(target);
+      active = false;
+    }
+    ~GuardVAList() {
+      if (active)
+        va_end(target);
+    }
+  };
+  va_list args;
+  va_start(args, msg);
+  GuardVAList args_guard(args);
+
+  va_list args_cp;
+  va_copy(args_cp, args);
+  GuardVAList args_copy_guard(args_cp);
+
+  std::string result;
+
+  array<char, 256> local_buff;
+  size_t size_with_null = local_buff.size();
+  auto ret = ::vsnprintf(local_buff.data(), size_with_null, msg, args_cp);
+
+  args_copy_guard.clear();
+
+  // handle empty expansion
+  if (ret == 0)
+    return result;
+  if (static_cast<size_t>(ret) < size_with_null) {
+    result.assign(local_buff.data(), static_cast<size_t>(ret));
+    return result;
+  }
+
+  // we did not provide a long enough buffer on our first attempt. The
+  // return value is the number of bytes (excluding the null byte) that are
+  // needed for formatting.
+  size_with_null = static_cast<size_t>(ret) + 1;
+  result.__resize_default_init(size_with_null - 1);
+  ret = ::vsnprintf(&result[0], size_with_null, msg, args);
+  _LIBCPP_ASSERT(static_cast<size_t>(ret) == (size_with_null - 1), "TODO");
+
+  return result;
+}
+
+const char* unwrap(string const& s) { return s.c_str(); }
+const char* unwrap(path const& p) { return p.native().c_str(); }
+template <class Arg>
+Arg const& unwrap(Arg const& a) {
+  static_assert(!is_class<Arg>::value, "cannot pass class here");
+  return a;
+}
+
+template <class... Args>
+string format_string(const char* fmt, Args const&... args) {
+  return format_string_imp(fmt, unwrap(args)...);
+}
+
+error_code capture_errno() {
+  _LIBCPP_ASSERT(errno, "Expected errno to be non-zero");
+  return error_code(errno, generic_category());
+}
+
+template <class T>
+T error_value();
+template <>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void error_value<void>() {}
+template <>
+bool error_value<bool>() {
+  return false;
+}
+template <>
+uintmax_t error_value<uintmax_t>() {
+  return uintmax_t(-1);
+}
+template <>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 file_time_type error_value<file_time_type>() {
+  return file_time_type::min();
+}
+template <>
+path error_value<path>() {
+  return {};
+}
+
+template <class T>
+struct ErrorHandler {
+  const char* func_name;
+  error_code* ec = nullptr;
+  const path* p1 = nullptr;
+  const path* p2 = nullptr;
+
+  ErrorHandler(const char* fname, error_code* ec, const path* p1 = nullptr,
+               const path* p2 = nullptr)
+      : func_name(fname), ec(ec), p1(p1), p2(p2) {
+    if (ec)
+      ec->clear();
+  }
+
+  T report(const error_code& m_ec) const {
+    if (ec) {
+      *ec = m_ec;
+      return error_value<T>();
+    }
+    string what = string("in ") + func_name;
+    switch (bool(p1) + bool(p2)) {
+    case 0:
+      __throw_filesystem_error(what, m_ec);
+    case 1:
+      __throw_filesystem_error(what, *p1, m_ec);
+    case 2:
+      __throw_filesystem_error(what, *p1, *p2, m_ec);
+    }
+    _LIBCPP_UNREACHABLE();
+  }
+
+  template <class... Args>
+  T report(const error_code& m_ec, const char* msg, Args const&... args) const {
+    if (ec) {
+      *ec = m_ec;
+      return error_value<T>();
+    }
+    string what =
+        string("in ") + func_name + ": " + format_string(msg, args...);
+    switch (bool(p1) + bool(p2)) {
+    case 0:
+      __throw_filesystem_error(what, m_ec);
+    case 1:
+      __throw_filesystem_error(what, *p1, m_ec);
+    case 2:
+      __throw_filesystem_error(what, *p1, *p2, m_ec);
+    }
+    _LIBCPP_UNREACHABLE();
+  }
+
+  T report(errc const& err) const { return report(make_error_code(err)); }
+
+  template <class... Args>
+  T report(errc const& err, const char* msg, Args const&... args) const {
+    return report(make_error_code(err), msg, args...);
+  }
+
+private:
+  ErrorHandler(ErrorHandler const&) = delete;
+  ErrorHandler& operator=(ErrorHandler const&) = delete;
+};
+
+using chrono::duration;
+using chrono::duration_cast;
+
+using TimeSpec = struct ::timespec;
+using StatT = struct ::stat;
+
+template <class FileTimeT, class TimeT,
+          bool IsFloat = is_floating_point<typename FileTimeT::rep>::value>
+struct time_util_base {
+  using rep = typename FileTimeT::rep;
+  using fs_duration = typename FileTimeT::duration;
+  using fs_seconds = duration<rep>;
+  using fs_nanoseconds = duration<rep, nano>;
+  using fs_microseconds = duration<rep, micro>;
+
+  static constexpr rep max_seconds =
+      duration_cast<fs_seconds>(FileTimeT::duration::max()).count();
+
+  static constexpr rep max_nsec =
+      duration_cast<fs_nanoseconds>(FileTimeT::duration::max() -
+                                    fs_seconds(max_seconds))
+          .count();
+
+  static constexpr rep min_seconds =
+      duration_cast<fs_seconds>(FileTimeT::duration::min()).count();
+
+  static constexpr rep min_nsec_timespec =
+      duration_cast<fs_nanoseconds>(
+          (FileTimeT::duration::min() - fs_seconds(min_seconds)) +
+          fs_seconds(1))
+          .count();
+
+private:
+#if _LIBCPP_STD_VER > 11 && !defined(_LIBCPP_HAS_NO_CXX14_CONSTEXPR)
+  static constexpr fs_duration get_min_nsecs() {
+    return duration_cast<fs_duration>(
+        fs_nanoseconds(min_nsec_timespec) -
+        duration_cast<fs_nanoseconds>(fs_seconds(1)));
+  }
+  // Static assert that these values properly round trip.
+  static_assert(fs_seconds(min_seconds) + get_min_nsecs() ==
+                    FileTimeT::duration::min(),
+                "value doesn't roundtrip");
+
+  static constexpr bool check_range() {
+    // This kinda sucks, but it's what happens when we don't have __int128_t.
+    if (sizeof(TimeT) == sizeof(rep)) {
+      typedef duration<long long, ratio<3600 * 24 * 365> > Years;
+      return duration_cast<Years>(fs_seconds(max_seconds)) > Years(250) &&
+             duration_cast<Years>(fs_seconds(min_seconds)) < Years(-250);
+    }
+    return max_seconds >= numeric_limits<TimeT>::max() &&
+           min_seconds <= numeric_limits<TimeT>::min();
+  }
+  static_assert(check_range(), "the representable range is unacceptable small");
+#endif
+};
+
+template <class FileTimeT, class TimeT>
+struct time_util_base<FileTimeT, TimeT, true> {
+  using rep = typename FileTimeT::rep;
+  using fs_duration = typename FileTimeT::duration;
+  using fs_seconds = duration<rep>;
+  using fs_nanoseconds = duration<rep, nano>;
+  using fs_microseconds = duration<rep, micro>;
+
+  static const rep max_seconds;
+  static const rep max_nsec;
+  static const rep min_seconds;
+  static const rep min_nsec_timespec;
+};
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::max_seconds =
+        duration_cast<fs_seconds>(FileTimeT::duration::max()).count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep time_util_base<FileTimeT, TimeT, true>::max_nsec =
+    duration_cast<fs_nanoseconds>(FileTimeT::duration::max() -
+                                  fs_seconds(max_seconds))
+        .count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::min_seconds =
+        duration_cast<fs_seconds>(FileTimeT::duration::min()).count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::min_nsec_timespec =
+        duration_cast<fs_nanoseconds>((FileTimeT::duration::min() -
+                                       fs_seconds(min_seconds)) +
+                                      fs_seconds(1))
+            .count();
+
+template <class FileTimeT, class TimeT, class TimeSpecT>
+struct time_util : time_util_base<FileTimeT, TimeT> {
+  using Base = time_util_base<FileTimeT, TimeT>;
+  using Base::max_nsec;
+  using Base::max_seconds;
+  using Base::min_nsec_timespec;
+  using Base::min_seconds;
+
+  using typename Base::fs_duration;
+  using typename Base::fs_microseconds;
+  using typename Base::fs_nanoseconds;
+  using typename Base::fs_seconds;
+
+public:
+  template <class CType, class ChronoType>
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 bool checked_set(CType* out,
+                                                        ChronoType time) {
+    using Lim = numeric_limits<CType>;
+    if (time > Lim::max() || time < Lim::min())
+      return false;
+    *out = static_cast<CType>(time);
+    return true;
+  }
+
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 bool is_representable(TimeSpecT tm) {
+    if (tm.tv_sec >= 0) {
+      return tm.tv_sec < max_seconds ||
+             (tm.tv_sec == max_seconds && tm.tv_nsec <= max_nsec);
+    } else if (tm.tv_sec == (min_seconds - 1)) {
+      return tm.tv_nsec >= min_nsec_timespec;
+    } else {
+      return tm.tv_sec >= min_seconds;
+    }
+  }
+
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 bool is_representable(FileTimeT tm) {
+    auto secs = duration_cast<fs_seconds>(tm.time_since_epoch());
+    auto nsecs = duration_cast<fs_nanoseconds>(tm.time_since_epoch() - secs);
+    if (nsecs.count() < 0) {
+      secs = secs + fs_seconds(1);
+      nsecs = nsecs + fs_seconds(1);
+    }
+    using TLim = numeric_limits<TimeT>;
+    if (secs.count() >= 0)
+      return secs.count() <= TLim::max();
+    return secs.count() >= TLim::min();
+  }
+
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 FileTimeT
+  convert_from_timespec(TimeSpecT tm) {
+    if (tm.tv_sec >= 0 || tm.tv_nsec == 0) {
+      return FileTimeT(fs_seconds(tm.tv_sec) +
+                       duration_cast<fs_duration>(fs_nanoseconds(tm.tv_nsec)));
+    } else { // tm.tv_sec < 0
+      auto adj_subsec = duration_cast<fs_duration>(fs_seconds(1) -
+                                                   fs_nanoseconds(tm.tv_nsec));
+      auto Dur = fs_seconds(tm.tv_sec + 1) - adj_subsec;
+      return FileTimeT(Dur);
+    }
+  }
+
+  template <class SubSecT>
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 bool
+  set_times_checked(TimeT* sec_out, SubSecT* subsec_out, FileTimeT tp) {
+    auto dur = tp.time_since_epoch();
+    auto sec_dur = duration_cast<fs_seconds>(dur);
+    auto subsec_dur = duration_cast<fs_nanoseconds>(dur - sec_dur);
+    // The tv_nsec and tv_usec fields must not be negative so adjust accordingly
+    if (subsec_dur.count() < 0) {
+      if (sec_dur.count() > min_seconds) {
+        sec_dur = sec_dur - fs_seconds(1);
+        subsec_dur = subsec_dur + fs_seconds(1);
+      } else {
+        subsec_dur = fs_nanoseconds::zero();
+      }
+    }
+    return checked_set(sec_out, sec_dur.count()) &&
+           checked_set(subsec_out, subsec_dur.count());
+  }
+  static _LIBCPP_CONSTEXPR_AFTER_CXX11 bool convert_to_timespec(TimeSpecT& dest,
+                                                                FileTimeT tp) {
+    if (!is_representable(tp))
+      return false;
+    return set_times_checked(&dest.tv_sec, &dest.tv_nsec, tp);
+  }
+};
+
+using fs_time = time_util<file_time_type, time_t, TimeSpec>;
+
+#if defined(__APPLE__)
+TimeSpec extract_mtime(StatT const& st) { return st.st_mtimespec; }
+TimeSpec extract_atime(StatT const& st) { return st.st_atimespec; }
+#else
+TimeSpec extract_mtime(StatT const& st) { return st.st_mtim; }
+TimeSpec extract_atime(StatT const& st) { return st.st_atim; }
+#endif
+
+// allow the utimes implementation to compile even it we're not going
+// to use it.
+
+bool posix_utimes(const path& p, std::array<TimeSpec, 2> const& TS,
+                  error_code& ec) {
+  using namespace chrono;
+  auto Convert = [](long nsec) {
+    using int_type = decltype(std::declval< ::timeval>().tv_usec);
+    auto dur = duration_cast<microseconds>(nanoseconds(nsec)).count();
+    return static_cast<int_type>(dur);
+  };
+  struct ::timeval ConvertedTS[2] = {{TS[0].tv_sec, Convert(TS[0].tv_nsec)},
+                                     {TS[1].tv_sec, Convert(TS[1].tv_nsec)}};
+  if (::utimes(p.c_str(), ConvertedTS) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  return false;
+}
+
+#if defined(_LIBCPP_USE_UTIMENSAT)
+bool posix_utimensat(const path& p, std::array<TimeSpec, 2> const& TS,
+                     error_code& ec) {
+  if (::utimensat(AT_FDCWD, p.c_str(), TS.data(), 0) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  return false;
+}
+#endif
+
+bool set_file_times(const path& p, std::array<TimeSpec, 2> const& TS,
+                    error_code& ec) {
+#if !defined(_LIBCPP_USE_UTIMENSAT)
+  return posix_utimes(p, TS, ec);
+#else
+  return posix_utimensat(p, TS, ec);
+#endif
+}
+
+} // namespace
+} // end namespace detail
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM
+
+#endif // FILESYSTEM_COMMON_H
diff --git a/lib/libcxx/src/filesystem/operations.cpp b/lib/libcxx/src/filesystem/operations.cpp
new file mode 100644
index 0000000000..876399fb4d
--- /dev/null
+++ b/lib/libcxx/src/filesystem/operations.cpp
@@ -0,0 +1,1782 @@
+//===--------------------- filesystem/ops.cpp -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "filesystem"
+#include "array"
+#include "iterator"
+#include "fstream"
+#include "random" /* for unique_path */
+#include "string_view"
+#include "type_traits"
+#include "vector"
+#include "cstdlib"
+#include "climits"
+
+#include "filesystem_common.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <time.h>
+#include <fcntl.h> /* values for fchmodat */
+
+#if defined(__linux__)
+#include <linux/version.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 33)
+#include <sys/sendfile.h>
+#define _LIBCPP_USE_SENDFILE
+#endif
+#elif defined(__APPLE__) || __has_include(<copyfile.h>)
+#include <copyfile.h>
+#define _LIBCPP_USE_COPYFILE
+#endif
+
+#if !defined(__APPLE__)
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+
+#if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME)
+#include <sys/time.h> // for gettimeofday and timeval
+#endif                // !defined(CLOCK_REALTIME)
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB)
+#pragma comment(lib, "rt")
+#endif
+
+#if defined(_LIBCPP_COMPILER_GCC)
+#if _GNUC_VER < 500
+#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+namespace {
+namespace parser {
+
+using string_view_t = path::__string_view;
+using string_view_pair = pair<string_view_t, string_view_t>;
+using PosPtr = path::value_type const*;
+
+struct PathParser {
+  enum ParserState : unsigned char {
+    // Zero is a special sentinel value used by default constructed iterators.
+    PS_BeforeBegin = path::iterator::_BeforeBegin,
+    PS_InRootName = path::iterator::_InRootName,
+    PS_InRootDir = path::iterator::_InRootDir,
+    PS_InFilenames = path::iterator::_InFilenames,
+    PS_InTrailingSep = path::iterator::_InTrailingSep,
+    PS_AtEnd = path::iterator::_AtEnd
+  };
+
+  const string_view_t Path;
+  string_view_t RawEntry;
+  ParserState State;
+
+private:
+  PathParser(string_view_t P, ParserState State) noexcept : Path(P),
+                                                            State(State) {}
+
+public:
+  PathParser(string_view_t P, string_view_t E, unsigned char S)
+      : Path(P), RawEntry(E), State(static_cast<ParserState>(S)) {
+    // S cannot be '0' or PS_BeforeBegin.
+  }
+
+  static PathParser CreateBegin(string_view_t P) noexcept {
+    PathParser PP(P, PS_BeforeBegin);
+    PP.increment();
+    return PP;
+  }
+
+  static PathParser CreateEnd(string_view_t P) noexcept {
+    PathParser PP(P, PS_AtEnd);
+    return PP;
+  }
+
+  PosPtr peek() const noexcept {
+    auto TkEnd = getNextTokenStartPos();
+    auto End = getAfterBack();
+    return TkEnd == End ? nullptr : TkEnd;
+  }
+
+  void increment() noexcept {
+    const PosPtr End = getAfterBack();
+    const PosPtr Start = getNextTokenStartPos();
+    if (Start == End)
+      return makeState(PS_AtEnd);
+
+    switch (State) {
+    case PS_BeforeBegin: {
+      PosPtr TkEnd = consumeSeparator(Start, End);
+      if (TkEnd)
+        return makeState(PS_InRootDir, Start, TkEnd);
+      else
+        return makeState(PS_InFilenames, Start, consumeName(Start, End));
+    }
+    case PS_InRootDir:
+      return makeState(PS_InFilenames, Start, consumeName(Start, End));
+
+    case PS_InFilenames: {
+      PosPtr SepEnd = consumeSeparator(Start, End);
+      if (SepEnd != End) {
+        PosPtr TkEnd = consumeName(SepEnd, End);
+        if (TkEnd)
+          return makeState(PS_InFilenames, SepEnd, TkEnd);
+      }
+      return makeState(PS_InTrailingSep, Start, SepEnd);
+    }
+
+    case PS_InTrailingSep:
+      return makeState(PS_AtEnd);
+
+    case PS_InRootName:
+    case PS_AtEnd:
+      _LIBCPP_UNREACHABLE();
+    }
+  }
+
+  void decrement() noexcept {
+    const PosPtr REnd = getBeforeFront();
+    const PosPtr RStart = getCurrentTokenStartPos() - 1;
+    if (RStart == REnd) // we're decrementing the begin
+      return makeState(PS_BeforeBegin);
+
+    switch (State) {
+    case PS_AtEnd: {
+      // Try to consume a trailing separator or root directory first.
+      if (PosPtr SepEnd = consumeSeparator(RStart, REnd)) {
+        if (SepEnd == REnd)
+          return makeState(PS_InRootDir, Path.data(), RStart + 1);
+        return makeState(PS_InTrailingSep, SepEnd + 1, RStart + 1);
+      } else {
+        PosPtr TkStart = consumeName(RStart, REnd);
+        return makeState(PS_InFilenames, TkStart + 1, RStart + 1);
+      }
+    }
+    case PS_InTrailingSep:
+      return makeState(PS_InFilenames, consumeName(RStart, REnd) + 1,
+                       RStart + 1);
+    case PS_InFilenames: {
+      PosPtr SepEnd = consumeSeparator(RStart, REnd);
+      if (SepEnd == REnd)
+        return makeState(PS_InRootDir, Path.data(), RStart + 1);
+      PosPtr TkEnd = consumeName(SepEnd, REnd);
+      return makeState(PS_InFilenames, TkEnd + 1, SepEnd + 1);
+    }
+    case PS_InRootDir:
+      // return makeState(PS_InRootName, Path.data(), RStart + 1);
+    case PS_InRootName:
+    case PS_BeforeBegin:
+      _LIBCPP_UNREACHABLE();
+    }
+  }
+
+  /// \brief Return a view with the "preferred representation" of the current
+  ///   element. For example trailing separators are represented as a '.'
+  string_view_t operator*() const noexcept {
+    switch (State) {
+    case PS_BeforeBegin:
+    case PS_AtEnd:
+      return "";
+    case PS_InRootDir:
+      return "/";
+    case PS_InTrailingSep:
+      return "";
+    case PS_InRootName:
+    case PS_InFilenames:
+      return RawEntry;
+    }
+    _LIBCPP_UNREACHABLE();
+  }
+
+  explicit operator bool() const noexcept {
+    return State != PS_BeforeBegin && State != PS_AtEnd;
+  }
+
+  PathParser& operator++() noexcept {
+    increment();
+    return *this;
+  }
+
+  PathParser& operator--() noexcept {
+    decrement();
+    return *this;
+  }
+
+  bool atEnd() const noexcept {
+    return State == PS_AtEnd;
+  }
+
+  bool inRootDir() const noexcept {
+    return State == PS_InRootDir;
+  }
+
+  bool inRootName() const noexcept {
+    return State == PS_InRootName;
+  }
+
+  bool inRootPath() const noexcept {
+    return inRootName() || inRootDir();
+  }
+
+private:
+  void makeState(ParserState NewState, PosPtr Start, PosPtr End) noexcept {
+    State = NewState;
+    RawEntry = string_view_t(Start, End - Start);
+  }
+  void makeState(ParserState NewState) noexcept {
+    State = NewState;
+    RawEntry = {};
+  }
+
+  PosPtr getAfterBack() const noexcept { return Path.data() + Path.size(); }
+
+  PosPtr getBeforeFront() const noexcept { return Path.data() - 1; }
+
+  /// \brief Return a pointer to the first character after the currently
+  ///   lexed element.
+  PosPtr getNextTokenStartPos() const noexcept {
+    switch (State) {
+    case PS_BeforeBegin:
+      return Path.data();
+    case PS_InRootName:
+    case PS_InRootDir:
+    case PS_InFilenames:
+      return &RawEntry.back() + 1;
+    case PS_InTrailingSep:
+    case PS_AtEnd:
+      return getAfterBack();
+    }
+    _LIBCPP_UNREACHABLE();
+  }
+
+  /// \brief Return a pointer to the first character in the currently lexed
+  ///   element.
+  PosPtr getCurrentTokenStartPos() const noexcept {
+    switch (State) {
+    case PS_BeforeBegin:
+    case PS_InRootName:
+      return &Path.front();
+    case PS_InRootDir:
+    case PS_InFilenames:
+    case PS_InTrailingSep:
+      return &RawEntry.front();
+    case PS_AtEnd:
+      return &Path.back() + 1;
+    }
+    _LIBCPP_UNREACHABLE();
+  }
+
+  PosPtr consumeSeparator(PosPtr P, PosPtr End) const noexcept {
+    if (P == End || *P != '/')
+      return nullptr;
+    const int Inc = P < End ? 1 : -1;
+    P += Inc;
+    while (P != End && *P == '/')
+      P += Inc;
+    return P;
+  }
+
+  PosPtr consumeName(PosPtr P, PosPtr End) const noexcept {
+    if (P == End || *P == '/')
+      return nullptr;
+    const int Inc = P < End ? 1 : -1;
+    P += Inc;
+    while (P != End && *P != '/')
+      P += Inc;
+    return P;
+  }
+};
+
+string_view_pair separate_filename(string_view_t const& s) {
+  if (s == "." || s == ".." || s.empty())
+    return string_view_pair{s, ""};
+  auto pos = s.find_last_of('.');
+  if (pos == string_view_t::npos || pos == 0)
+    return string_view_pair{s, string_view_t{}};
+  return string_view_pair{s.substr(0, pos), s.substr(pos)};
+}
+
+string_view_t createView(PosPtr S, PosPtr E) noexcept {
+  return {S, static_cast<size_t>(E - S) + 1};
+}
+
+} // namespace parser
+} // namespace
+
+//                       POSIX HELPERS
+
+namespace detail {
+namespace {
+
+using value_type = path::value_type;
+using string_type = path::string_type;
+
+struct FileDescriptor {
+  const path& name;
+  int fd = -1;
+  StatT m_stat;
+  file_status m_status;
+
+  template <class... Args>
+  static FileDescriptor create(const path* p, error_code& ec, Args... args) {
+    ec.clear();
+    int fd;
+    if ((fd = ::open(p->c_str(), args...)) == -1) {
+      ec = capture_errno();
+      return FileDescriptor{p};
+    }
+    return FileDescriptor(p, fd);
+  }
+
+  template <class... Args>
+  static FileDescriptor create_with_status(const path* p, error_code& ec,
+                                           Args... args) {
+    FileDescriptor fd = create(p, ec, args...);
+    if (!ec)
+      fd.refresh_status(ec);
+
+    return fd;
+  }
+
+  file_status get_status() const { return m_status; }
+  StatT const& get_stat() const { return m_stat; }
+
+  bool status_known() const { return _VSTD_FS::status_known(m_status); }
+
+  file_status refresh_status(error_code& ec);
+
+  void close() noexcept {
+    if (fd != -1)
+      ::close(fd);
+    fd = -1;
+  }
+
+  FileDescriptor(FileDescriptor&& other)
+      : name(other.name), fd(other.fd), m_stat(other.m_stat),
+        m_status(other.m_status) {
+    other.fd = -1;
+    other.m_status = file_status{};
+  }
+
+  ~FileDescriptor() { close(); }
+
+  FileDescriptor(FileDescriptor const&) = delete;
+  FileDescriptor& operator=(FileDescriptor const&) = delete;
+
+private:
+  explicit FileDescriptor(const path* p, int fd = -1) : name(*p), fd(fd) {}
+};
+
+perms posix_get_perms(const StatT& st) noexcept {
+  return static_cast<perms>(st.st_mode) & perms::mask;
+}
+
+::mode_t posix_convert_perms(perms prms) {
+  return static_cast< ::mode_t>(prms & perms::mask);
+}
+
+file_status create_file_status(error_code& m_ec, path const& p,
+                               const StatT& path_stat, error_code* ec) {
+  if (ec)
+    *ec = m_ec;
+  if (m_ec && (m_ec.value() == ENOENT || m_ec.value() == ENOTDIR)) {
+    return file_status(file_type::not_found);
+  } else if (m_ec) {
+    ErrorHandler<void> err("posix_stat", ec, &p);
+    err.report(m_ec, "failed to determine attributes for the specified path");
+    return file_status(file_type::none);
+  }
+  // else
+
+  file_status fs_tmp;
+  auto const mode = path_stat.st_mode;
+  if (S_ISLNK(mode))
+    fs_tmp.type(file_type::symlink);
+  else if (S_ISREG(mode))
+    fs_tmp.type(file_type::regular);
+  else if (S_ISDIR(mode))
+    fs_tmp.type(file_type::directory);
+  else if (S_ISBLK(mode))
+    fs_tmp.type(file_type::block);
+  else if (S_ISCHR(mode))
+    fs_tmp.type(file_type::character);
+  else if (S_ISFIFO(mode))
+    fs_tmp.type(file_type::fifo);
+  else if (S_ISSOCK(mode))
+    fs_tmp.type(file_type::socket);
+  else
+    fs_tmp.type(file_type::unknown);
+
+  fs_tmp.permissions(detail::posix_get_perms(path_stat));
+  return fs_tmp;
+}
+
+file_status posix_stat(path const& p, StatT& path_stat, error_code* ec) {
+  error_code m_ec;
+  if (::stat(p.c_str(), &path_stat) == -1)
+    m_ec = detail::capture_errno();
+  return create_file_status(m_ec, p, path_stat, ec);
+}
+
+file_status posix_stat(path const& p, error_code* ec) {
+  StatT path_stat;
+  return posix_stat(p, path_stat, ec);
+}
+
+file_status posix_lstat(path const& p, StatT& path_stat, error_code* ec) {
+  error_code m_ec;
+  if (::lstat(p.c_str(), &path_stat) == -1)
+    m_ec = detail::capture_errno();
+  return create_file_status(m_ec, p, path_stat, ec);
+}
+
+file_status posix_lstat(path const& p, error_code* ec) {
+  StatT path_stat;
+  return posix_lstat(p, path_stat, ec);
+}
+
+// http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html
+bool posix_ftruncate(const FileDescriptor& fd, off_t to_size, error_code& ec) {
+  if (::ftruncate(fd.fd, to_size) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  ec.clear();
+  return false;
+}
+
+bool posix_fchmod(const FileDescriptor& fd, const StatT& st, error_code& ec) {
+  if (::fchmod(fd.fd, st.st_mode) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  ec.clear();
+  return false;
+}
+
+bool stat_equivalent(const StatT& st1, const StatT& st2) {
+  return (st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
+}
+
+file_status FileDescriptor::refresh_status(error_code& ec) {
+  // FD must be open and good.
+  m_status = file_status{};
+  m_stat = {};
+  error_code m_ec;
+  if (::fstat(fd, &m_stat) == -1)
+    m_ec = capture_errno();
+  m_status = create_file_status(m_ec, name, m_stat, &ec);
+  return m_status;
+}
+} // namespace
+} // end namespace detail
+
+using detail::capture_errno;
+using detail::ErrorHandler;
+using detail::StatT;
+using detail::TimeSpec;
+using parser::createView;
+using parser::PathParser;
+using parser::string_view_t;
+
+const bool _FilesystemClock::is_steady;
+
+_FilesystemClock::time_point _FilesystemClock::now() noexcept {
+  typedef chrono::duration<rep> __secs;
+#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_REALTIME)
+  typedef chrono::duration<rep, nano> __nsecs;
+  struct timespec tp;
+  if (0 != clock_gettime(CLOCK_REALTIME, &tp))
+    __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");
+  return time_point(__secs(tp.tv_sec) +
+                    chrono::duration_cast<duration>(__nsecs(tp.tv_nsec)));
+#else
+  typedef chrono::duration<rep, micro> __microsecs;
+  timeval tv;
+  gettimeofday(&tv, 0);
+  return time_point(__secs(tv.tv_sec) + __microsecs(tv.tv_usec));
+#endif // _LIBCPP_USE_CLOCK_GETTIME && CLOCK_REALTIME
+}
+
+filesystem_error::~filesystem_error() {}
+
+void filesystem_error::__create_what(int __num_paths) {
+  const char* derived_what = system_error::what();
+  __storage_->__what_ = [&]() -> string {
+    const char* p1 = path1().native().empty() ? "\"\"" : path1().c_str();
+    const char* p2 = path2().native().empty() ? "\"\"" : path2().c_str();
+    switch (__num_paths) {
+    default:
+      return detail::format_string("filesystem error: %s", derived_what);
+    case 1:
+      return detail::format_string("filesystem error: %s [%s]", derived_what,
+                                   p1);
+    case 2:
+      return detail::format_string("filesystem error: %s [%s] [%s]",
+                                   derived_what, p1, p2);
+    }
+  }();
+}
+
+static path __do_absolute(const path& p, path* cwd, error_code* ec) {
+  if (ec)
+    ec->clear();
+  if (p.is_absolute())
+    return p;
+  *cwd = __current_path(ec);
+  if (ec && *ec)
+    return {};
+  return (*cwd) / p;
+}
+
+path __absolute(const path& p, error_code* ec) {
+  path cwd;
+  return __do_absolute(p, &cwd, ec);
+}
+
+path __canonical(path const& orig_p, error_code* ec) {
+  path cwd;
+  ErrorHandler<path> err("canonical", ec, &orig_p, &cwd);
+
+  path p = __do_absolute(orig_p, &cwd, ec);
+#if _POSIX_VERSION >= 200112
+  std::unique_ptr<char, decltype(&::free)>
+    hold(::realpath(p.c_str(), nullptr), &::free);
+  if (hold.get() == nullptr)
+    return err.report(capture_errno());
+  return {hold.get()};
+#else
+  char buff[PATH_MAX + 1];
+  char* ret;
+  if ((ret = ::realpath(p.c_str(), buff)) == nullptr)
+    return err.report(capture_errno());
+  return {ret};
+#endif
+}
+
+void __copy(const path& from, const path& to, copy_options options,
+            error_code* ec) {
+  ErrorHandler<void> err("copy", ec, &from, &to);
+
+  const bool sym_status = bool(
+      options & (copy_options::create_symlinks | copy_options::skip_symlinks));
+
+  const bool sym_status2 = bool(options & copy_options::copy_symlinks);
+
+  error_code m_ec1;
+  StatT f_st = {};
+  const file_status f = sym_status || sym_status2
+                            ? detail::posix_lstat(from, f_st, &m_ec1)
+                            : detail::posix_stat(from, f_st, &m_ec1);
+  if (m_ec1)
+    return err.report(m_ec1);
+
+  StatT t_st = {};
+  const file_status t = sym_status ? detail::posix_lstat(to, t_st, &m_ec1)
+                                   : detail::posix_stat(to, t_st, &m_ec1);
+
+  if (not status_known(t))
+    return err.report(m_ec1);
+
+  if (!exists(f) || is_other(f) || is_other(t) ||
+      (is_directory(f) && is_regular_file(t)) ||
+      detail::stat_equivalent(f_st, t_st)) {
+    return err.report(errc::function_not_supported);
+  }
+
+  if (ec)
+    ec->clear();
+
+  if (is_symlink(f)) {
+    if (bool(copy_options::skip_symlinks & options)) {
+      // do nothing
+    } else if (not exists(t)) {
+      __copy_symlink(from, to, ec);
+    } else {
+      return err.report(errc::file_exists);
+    }
+    return;
+  } else if (is_regular_file(f)) {
+    if (bool(copy_options::directories_only & options)) {
+      // do nothing
+    } else if (bool(copy_options::create_symlinks & options)) {
+      __create_symlink(from, to, ec);
+    } else if (bool(copy_options::create_hard_links & options)) {
+      __create_hard_link(from, to, ec);
+    } else if (is_directory(t)) {
+      __copy_file(from, to / from.filename(), options, ec);
+    } else {
+      __copy_file(from, to, options, ec);
+    }
+    return;
+  } else if (is_directory(f) && bool(copy_options::create_symlinks & options)) {
+    return err.report(errc::is_a_directory);
+  } else if (is_directory(f) && (bool(copy_options::recursive & options) ||
+                                 copy_options::none == options)) {
+
+    if (!exists(t)) {
+      // create directory to with attributes from 'from'.
+      __create_directory(to, from, ec);
+      if (ec && *ec) {
+        return;
+      }
+    }
+    directory_iterator it =
+        ec ? directory_iterator(from, *ec) : directory_iterator(from);
+    if (ec && *ec) {
+      return;
+    }
+    error_code m_ec2;
+    for (; it != directory_iterator(); it.increment(m_ec2)) {
+      if (m_ec2) {
+        return err.report(m_ec2);
+      }
+      __copy(it->path(), to / it->path().filename(),
+             options | copy_options::__in_recursive_copy, ec);
+      if (ec && *ec) {
+        return;
+      }
+    }
+  }
+}
+
+namespace detail {
+namespace {
+
+#ifdef _LIBCPP_USE_SENDFILE
+bool copy_file_impl_sendfile(FileDescriptor& read_fd, FileDescriptor& write_fd,
+                             error_code& ec) {
+
+  size_t count = read_fd.get_stat().st_size;
+  do {
+    ssize_t res;
+    if ((res = ::sendfile(write_fd.fd, read_fd.fd, nullptr, count)) == -1) {
+      ec = capture_errno();
+      return false;
+    }
+    count -= res;
+  } while (count > 0);
+
+  ec.clear();
+
+  return true;
+}
+#elif defined(_LIBCPP_USE_COPYFILE)
+bool copy_file_impl_copyfile(FileDescriptor& read_fd, FileDescriptor& write_fd,
+                             error_code& ec) {
+  struct CopyFileState {
+    copyfile_state_t state;
+    CopyFileState() { state = copyfile_state_alloc(); }
+    ~CopyFileState() { copyfile_state_free(state); }
+
+  private:
+    CopyFileState(CopyFileState const&) = delete;
+    CopyFileState& operator=(CopyFileState const&) = delete;
+  };
+
+  CopyFileState cfs;
+  if (fcopyfile(read_fd.fd, write_fd.fd, cfs.state, COPYFILE_DATA) < 0) {
+    ec = capture_errno();
+    return false;
+  }
+
+  ec.clear();
+  return true;
+}
+#endif
+
+// Note: This function isn't guarded by ifdef's even though it may be unused
+// in order to assure it still compiles.
+__attribute__((unused)) bool copy_file_impl_default(FileDescriptor& read_fd,
+                                                    FileDescriptor& write_fd,
+                                                    error_code& ec) {
+  ifstream in;
+  in.__open(read_fd.fd, ios::binary);
+  if (!in.is_open()) {
+    // This assumes that __open didn't reset the error code.
+    ec = capture_errno();
+    return false;
+  }
+  ofstream out;
+  out.__open(write_fd.fd, ios::binary);
+  if (!out.is_open()) {
+    ec = capture_errno();
+    return false;
+  }
+
+  if (in.good() && out.good()) {
+    using InIt = istreambuf_iterator<char>;
+    using OutIt = ostreambuf_iterator<char>;
+    InIt bin(in);
+    InIt ein;
+    OutIt bout(out);
+    copy(bin, ein, bout);
+  }
+  if (out.fail() || in.fail()) {
+    ec = make_error_code(errc::io_error);
+    return false;
+  }
+
+  ec.clear();
+  return true;
+}
+
+bool copy_file_impl(FileDescriptor& from, FileDescriptor& to, error_code& ec) {
+#if defined(_LIBCPP_USE_SENDFILE)
+  return copy_file_impl_sendfile(from, to, ec);
+#elif defined(_LIBCPP_USE_COPYFILE)
+  return copy_file_impl_copyfile(from, to, ec);
+#else
+  return copy_file_impl_default(from, to, ec);
+#endif
+}
+
+} // namespace
+} // namespace detail
+
+bool __copy_file(const path& from, const path& to, copy_options options,
+                 error_code* ec) {
+  using detail::FileDescriptor;
+  ErrorHandler<bool> err("copy_file", ec, &to, &from);
+
+  error_code m_ec;
+  FileDescriptor from_fd =
+      FileDescriptor::create_with_status(&from, m_ec, O_RDONLY | O_NONBLOCK);
+  if (m_ec)
+    return err.report(m_ec);
+
+  auto from_st = from_fd.get_status();
+  StatT const& from_stat = from_fd.get_stat();
+  if (!is_regular_file(from_st)) {
+    if (not m_ec)
+      m_ec = make_error_code(errc::not_supported);
+    return err.report(m_ec);
+  }
+
+  const bool skip_existing = bool(copy_options::skip_existing & options);
+  const bool update_existing = bool(copy_options::update_existing & options);
+  const bool overwrite_existing =
+      bool(copy_options::overwrite_existing & options);
+
+  StatT to_stat_path;
+  file_status to_st = detail::posix_stat(to, to_stat_path, &m_ec);
+  if (!status_known(to_st))
+    return err.report(m_ec);
+
+  const bool to_exists = exists(to_st);
+  if (to_exists && !is_regular_file(to_st))
+    return err.report(errc::not_supported);
+
+  if (to_exists && detail::stat_equivalent(from_stat, to_stat_path))
+    return err.report(errc::file_exists);
+
+  if (to_exists && skip_existing)
+    return false;
+
+  bool ShouldCopy = [&]() {
+    if (to_exists && update_existing) {
+      auto from_time = detail::extract_mtime(from_stat);
+      auto to_time = detail::extract_mtime(to_stat_path);
+      if (from_time.tv_sec < to_time.tv_sec)
+        return false;
+      if (from_time.tv_sec == to_time.tv_sec &&
+          from_time.tv_nsec <= to_time.tv_nsec)
+        return false;
+      return true;
+    }
+    if (!to_exists || overwrite_existing)
+      return true;
+    return err.report(errc::file_exists);
+  }();
+  if (!ShouldCopy)
+    return false;
+
+  // Don't truncate right away. We may not be opening the file we originally
+  // looked at; we'll check this later.
+  int to_open_flags = O_WRONLY;
+  if (!to_exists)
+    to_open_flags |= O_CREAT;
+  FileDescriptor to_fd = FileDescriptor::create_with_status(
+      &to, m_ec, to_open_flags, from_stat.st_mode);
+  if (m_ec)
+    return err.report(m_ec);
+
+  if (to_exists) {
+    // Check that the file we initially stat'ed is equivalent to the one
+    // we opened.
+    // FIXME: report this better.
+    if (!detail::stat_equivalent(to_stat_path, to_fd.get_stat()))
+      return err.report(errc::bad_file_descriptor);
+
+    // Set the permissions and truncate the file we opened.
+    if (detail::posix_fchmod(to_fd, from_stat, m_ec))
+      return err.report(m_ec);
+    if (detail::posix_ftruncate(to_fd, 0, m_ec))
+      return err.report(m_ec);
+  }
+
+  if (!copy_file_impl(from_fd, to_fd, m_ec)) {
+    // FIXME: Remove the dest file if we failed, and it didn't exist previously.
+    return err.report(m_ec);
+  }
+
+  return true;
+}
+
+void __copy_symlink(const path& existing_symlink, const path& new_symlink,
+                    error_code* ec) {
+  const path real_path(__read_symlink(existing_symlink, ec));
+  if (ec && *ec) {
+    return;
+  }
+  // NOTE: proposal says you should detect if you should call
+  // create_symlink or create_directory_symlink. I don't think this
+  // is needed with POSIX
+  __create_symlink(real_path, new_symlink, ec);
+}
+
+bool __create_directories(const path& p, error_code* ec) {
+  ErrorHandler<bool> err("create_directories", ec, &p);
+
+  error_code m_ec;
+  auto const st = detail::posix_stat(p, &m_ec);
+  if (!status_known(st))
+    return err.report(m_ec);
+  else if (is_directory(st))
+    return false;
+  else if (exists(st))
+    return err.report(errc::file_exists);
+
+  const path parent = p.parent_path();
+  if (!parent.empty()) {
+    const file_status parent_st = status(parent, m_ec);
+    if (not status_known(parent_st))
+      return err.report(m_ec);
+    if (not exists(parent_st)) {
+      __create_directories(parent, ec);
+      if (ec && *ec) {
+        return false;
+      }
+    }
+  }
+  return __create_directory(p, ec);
+}
+
+bool __create_directory(const path& p, error_code* ec) {
+  ErrorHandler<bool> err("create_directory", ec, &p);
+
+  if (::mkdir(p.c_str(), static_cast<int>(perms::all)) == 0)
+    return true;
+  if (errno != EEXIST)
+    err.report(capture_errno());
+  return false;
+}
+
+bool __create_directory(path const& p, path const& attributes, error_code* ec) {
+  ErrorHandler<bool> err("create_directory", ec, &p, &attributes);
+
+  StatT attr_stat;
+  error_code mec;
+  auto st = detail::posix_stat(attributes, attr_stat, &mec);
+  if (!status_known(st))
+    return err.report(mec);
+  if (!is_directory(st))
+    return err.report(errc::not_a_directory,
+                      "the specified attribute path is invalid");
+
+  if (::mkdir(p.c_str(), attr_stat.st_mode) == 0)
+    return true;
+  if (errno != EEXIST)
+    err.report(capture_errno());
+  return false;
+}
+
+void __create_directory_symlink(path const& from, path const& to,
+                                error_code* ec) {
+  ErrorHandler<void> err("create_directory_symlink", ec, &from, &to);
+  if (::symlink(from.c_str(), to.c_str()) != 0)
+    return err.report(capture_errno());
+}
+
+void __create_hard_link(const path& from, const path& to, error_code* ec) {
+  ErrorHandler<void> err("create_hard_link", ec, &from, &to);
+  if (::link(from.c_str(), to.c_str()) == -1)
+    return err.report(capture_errno());
+}
+
+void __create_symlink(path const& from, path const& to, error_code* ec) {
+  ErrorHandler<void> err("create_symlink", ec, &from, &to);
+  if (::symlink(from.c_str(), to.c_str()) == -1)
+    return err.report(capture_errno());
+}
+
+path __current_path(error_code* ec) {
+  ErrorHandler<path> err("current_path", ec);
+
+  auto size = ::pathconf(".", _PC_PATH_MAX);
+  _LIBCPP_ASSERT(size >= 0, "pathconf returned a 0 as max size");
+
+  auto buff = unique_ptr<char[]>(new char[size + 1]);
+  char* ret;
+  if ((ret = ::getcwd(buff.get(), static_cast<size_t>(size))) == nullptr)
+    return err.report(capture_errno(), "call to getcwd failed");
+
+  return {buff.get()};
+}
+
+void __current_path(const path& p, error_code* ec) {
+  ErrorHandler<void> err("current_path", ec, &p);
+  if (::chdir(p.c_str()) == -1)
+    err.report(capture_errno());
+}
+
+bool __equivalent(const path& p1, const path& p2, error_code* ec) {
+  ErrorHandler<bool> err("equivalent", ec, &p1, &p2);
+
+  error_code ec1, ec2;
+  StatT st1 = {}, st2 = {};
+  auto s1 = detail::posix_stat(p1.native(), st1, &ec1);
+  if (!exists(s1))
+    return err.report(errc::not_supported);
+  auto s2 = detail::posix_stat(p2.native(), st2, &ec2);
+  if (!exists(s2))
+    return err.report(errc::not_supported);
+
+  return detail::stat_equivalent(st1, st2);
+}
+
+uintmax_t __file_size(const path& p, error_code* ec) {
+  ErrorHandler<uintmax_t> err("file_size", ec, &p);
+
+  error_code m_ec;
+  StatT st;
+  file_status fst = detail::posix_stat(p, st, &m_ec);
+  if (!exists(fst) || !is_regular_file(fst)) {
+    errc error_kind =
+        is_directory(fst) ? errc::is_a_directory : errc::not_supported;
+    if (!m_ec)
+      m_ec = make_error_code(error_kind);
+    return err.report(m_ec);
+  }
+  // is_regular_file(p) == true
+  return static_cast<uintmax_t>(st.st_size);
+}
+
+uintmax_t __hard_link_count(const path& p, error_code* ec) {
+  ErrorHandler<uintmax_t> err("hard_link_count", ec, &p);
+
+  error_code m_ec;
+  StatT st;
+  detail::posix_stat(p, st, &m_ec);
+  if (m_ec)
+    return err.report(m_ec);
+  return static_cast<uintmax_t>(st.st_nlink);
+}
+
+bool __fs_is_empty(const path& p, error_code* ec) {
+  ErrorHandler<bool> err("is_empty", ec, &p);
+
+  error_code m_ec;
+  StatT pst;
+  auto st = detail::posix_stat(p, pst, &m_ec);
+  if (m_ec)
+    return err.report(m_ec);
+  else if (!is_directory(st) && !is_regular_file(st))
+    return err.report(errc::not_supported);
+  else if (is_directory(st)) {
+    auto it = ec ? directory_iterator(p, *ec) : directory_iterator(p);
+    if (ec && *ec)
+      return false;
+    return it == directory_iterator{};
+  } else if (is_regular_file(st))
+    return static_cast<uintmax_t>(pst.st_size) == 0;
+
+  _LIBCPP_UNREACHABLE();
+}
+
+static file_time_type __extract_last_write_time(const path& p, const StatT& st,
+                                                error_code* ec) {
+  using detail::fs_time;
+  ErrorHandler<file_time_type> err("last_write_time", ec, &p);
+
+  auto ts = detail::extract_mtime(st);
+  if (!fs_time::is_representable(ts))
+    return err.report(errc::value_too_large);
+
+  return fs_time::convert_from_timespec(ts);
+}
+
+file_time_type __last_write_time(const path& p, error_code* ec) {
+  using namespace chrono;
+  ErrorHandler<file_time_type> err("last_write_time", ec, &p);
+
+  error_code m_ec;
+  StatT st;
+  detail::posix_stat(p, st, &m_ec);
+  if (m_ec)
+    return err.report(m_ec);
+  return __extract_last_write_time(p, st, ec);
+}
+
+void __last_write_time(const path& p, file_time_type new_time, error_code* ec) {
+  using detail::fs_time;
+  ErrorHandler<void> err("last_write_time", ec, &p);
+
+  error_code m_ec;
+  array<TimeSpec, 2> tbuf;
+#if !defined(_LIBCPP_USE_UTIMENSAT)
+  // This implementation has a race condition between determining the
+  // last access time and attempting to set it to the same value using
+  // ::utimes
+  StatT st;
+  file_status fst = detail::posix_stat(p, st, &m_ec);
+  if (m_ec)
+    return err.report(m_ec);
+  tbuf[0] = detail::extract_atime(st);
+#else
+  tbuf[0].tv_sec = 0;
+  tbuf[0].tv_nsec = UTIME_OMIT;
+#endif
+  if (!fs_time::convert_to_timespec(tbuf[1], new_time))
+    return err.report(errc::value_too_large);
+
+  detail::set_file_times(p, tbuf, m_ec);
+  if (m_ec)
+    return err.report(m_ec);
+}
+
+void __permissions(const path& p, perms prms, perm_options opts,
+                   error_code* ec) {
+  ErrorHandler<void> err("permissions", ec, &p);
+
+  auto has_opt = [&](perm_options o) { return bool(o & opts); };
+  const bool resolve_symlinks = !has_opt(perm_options::nofollow);
+  const bool add_perms = has_opt(perm_options::add);
+  const bool remove_perms = has_opt(perm_options::remove);
+  _LIBCPP_ASSERT(
+      (add_perms + remove_perms + has_opt(perm_options::replace)) == 1,
+      "One and only one of the perm_options constants replace, add, or remove "
+      "is present in opts");
+
+  bool set_sym_perms = false;
+  prms &= perms::mask;
+  if (!resolve_symlinks || (add_perms || remove_perms)) {
+    error_code m_ec;
+    file_status st = resolve_symlinks ? detail::posix_stat(p, &m_ec)
+                                      : detail::posix_lstat(p, &m_ec);
+    set_sym_perms = is_symlink(st);
+    if (m_ec)
+      return err.report(m_ec);
+    _LIBCPP_ASSERT(st.permissions() != perms::unknown,
+                   "Permissions unexpectedly unknown");
+    if (add_perms)
+      prms |= st.permissions();
+    else if (remove_perms)
+      prms = st.permissions() & ~prms;
+  }
+  const auto real_perms = detail::posix_convert_perms(prms);
+
+#if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD)
+  const int flags = set_sym_perms ? AT_SYMLINK_NOFOLLOW : 0;
+  if (::fchmodat(AT_FDCWD, p.c_str(), real_perms, flags) == -1) {
+    return err.report(capture_errno());
+  }
+#else
+  if (set_sym_perms)
+    return err.report(errc::operation_not_supported);
+  if (::chmod(p.c_str(), real_perms) == -1) {
+    return err.report(capture_errno());
+  }
+#endif
+}
+
+path __read_symlink(const path& p, error_code* ec) {
+  ErrorHandler<path> err("read_symlink", ec, &p);
+
+#ifdef PATH_MAX
+  struct NullDeleter { void operator()(void*) const {} };
+  const size_t size = PATH_MAX + 1;
+  char stack_buff[size];
+  auto buff = std::unique_ptr<char[], NullDeleter>(stack_buff);
+#else
+  StatT sb;
+  if (::lstat(p.c_str(), &sb) == -1) {
+    return err.report(capture_errno());
+  }
+  const size_t size = sb.st_size + 1;
+  auto buff = unique_ptr<char[]>(new char[size]);
+#endif
+  ::ssize_t ret;
+  if ((ret = ::readlink(p.c_str(), buff.get(), size)) == -1)
+    return err.report(capture_errno());
+  _LIBCPP_ASSERT(ret > 0, "TODO");
+  if (static_cast<size_t>(ret) >= size)
+    return err.report(errc::value_too_large);
+  buff[ret] = 0;
+  return {buff.get()};
+}
+
+bool __remove(const path& p, error_code* ec) {
+  ErrorHandler<bool> err("remove", ec, &p);
+  if (::remove(p.c_str()) == -1) {
+    if (errno != ENOENT)
+      err.report(capture_errno());
+    return false;
+  }
+  return true;
+}
+
+namespace {
+
+uintmax_t remove_all_impl(path const& p, error_code& ec) {
+  const auto npos = static_cast<uintmax_t>(-1);
+  const file_status st = __symlink_status(p, &ec);
+  if (ec)
+    return npos;
+  uintmax_t count = 1;
+  if (is_directory(st)) {
+    for (directory_iterator it(p, ec); !ec && it != directory_iterator();
+         it.increment(ec)) {
+      auto other_count = remove_all_impl(it->path(), ec);
+      if (ec)
+        return npos;
+      count += other_count;
+    }
+    if (ec)
+      return npos;
+  }
+  if (!__remove(p, &ec))
+    return npos;
+  return count;
+}
+
+} // end namespace
+
+uintmax_t __remove_all(const path& p, error_code* ec) {
+  ErrorHandler<uintmax_t> err("remove_all", ec, &p);
+
+  error_code mec;
+  auto count = remove_all_impl(p, mec);
+  if (mec) {
+    if (mec == errc::no_such_file_or_directory)
+      return 0;
+    return err.report(mec);
+  }
+  return count;
+}
+
+void __rename(const path& from, const path& to, error_code* ec) {
+  ErrorHandler<void> err("rename", ec, &from, &to);
+  if (::rename(from.c_str(), to.c_str()) == -1)
+    err.report(capture_errno());
+}
+
+void __resize_file(const path& p, uintmax_t size, error_code* ec) {
+  ErrorHandler<void> err("resize_file", ec, &p);
+  if (::truncate(p.c_str(), static_cast< ::off_t>(size)) == -1)
+    return err.report(capture_errno());
+}
+
+space_info __space(const path& p, error_code* ec) {
+  ErrorHandler<void> err("space", ec, &p);
+  space_info si;
+  struct statvfs m_svfs = {};
+  if (::statvfs(p.c_str(), &m_svfs) == -1) {
+    err.report(capture_errno());
+    si.capacity = si.free = si.available = static_cast<uintmax_t>(-1);
+    return si;
+  }
+  // Multiply with overflow checking.
+  auto do_mult = [&](uintmax_t& out, uintmax_t other) {
+    out = other * m_svfs.f_frsize;
+    if (other == 0 || out / other != m_svfs.f_frsize)
+      out = static_cast<uintmax_t>(-1);
+  };
+  do_mult(si.capacity, m_svfs.f_blocks);
+  do_mult(si.free, m_svfs.f_bfree);
+  do_mult(si.available, m_svfs.f_bavail);
+  return si;
+}
+
+file_status __status(const path& p, error_code* ec) {
+  return detail::posix_stat(p, ec);
+}
+
+file_status __symlink_status(const path& p, error_code* ec) {
+  return detail::posix_lstat(p, ec);
+}
+
+path __temp_directory_path(error_code* ec) {
+  ErrorHandler<path> err("temp_directory_path", ec);
+
+  const char* env_paths[] = {"TMPDIR", "TMP", "TEMP", "TEMPDIR"};
+  const char* ret = nullptr;
+
+  for (auto& ep : env_paths)
+    if ((ret = getenv(ep)))
+      break;
+  if (ret == nullptr)
+    ret = "/tmp";
+
+  path p(ret);
+  error_code m_ec;
+  file_status st = detail::posix_stat(p, &m_ec);
+  if (!status_known(st))
+    return err.report(m_ec, "cannot access path \"%s\"", p);
+
+  if (!exists(st) || !is_directory(st))
+    return err.report(errc::not_a_directory, "path \"%s\" is not a directory",
+                      p);
+
+  return p;
+}
+
+path __weakly_canonical(const path& p, error_code* ec) {
+  ErrorHandler<path> err("weakly_canonical", ec, &p);
+
+  if (p.empty())
+    return __canonical("", ec);
+
+  path result;
+  path tmp;
+  tmp.__reserve(p.native().size());
+  auto PP = PathParser::CreateEnd(p.native());
+  --PP;
+  vector<string_view_t> DNEParts;
+
+  while (PP.State != PathParser::PS_BeforeBegin) {
+    tmp.assign(createView(p.native().data(), &PP.RawEntry.back()));
+    error_code m_ec;
+    file_status st = __status(tmp, &m_ec);
+    if (!status_known(st)) {
+      return err.report(m_ec);
+    } else if (exists(st)) {
+      result = __canonical(tmp, ec);
+      break;
+    }
+    DNEParts.push_back(*PP);
+    --PP;
+  }
+  if (PP.State == PathParser::PS_BeforeBegin)
+    result = __canonical("", ec);
+  if (ec)
+    ec->clear();
+  if (DNEParts.empty())
+    return result;
+  for (auto It = DNEParts.rbegin(); It != DNEParts.rend(); ++It)
+    result /= *It;
+  return result.lexically_normal();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+//                            path definitions
+///////////////////////////////////////////////////////////////////////////////
+
+constexpr path::value_type path::preferred_separator;
+
+path& path::replace_extension(path const& replacement) {
+  path p = extension();
+  if (not p.empty()) {
+    __pn_.erase(__pn_.size() - p.native().size());
+  }
+  if (!replacement.empty()) {
+    if (replacement.native()[0] != '.') {
+      __pn_ += ".";
+    }
+    __pn_.append(replacement.__pn_);
+  }
+  return *this;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// path.decompose
+
+string_view_t path::__root_name() const {
+  auto PP = PathParser::CreateBegin(__pn_);
+  if (PP.State == PathParser::PS_InRootName)
+    return *PP;
+  return {};
+}
+
+string_view_t path::__root_directory() const {
+  auto PP = PathParser::CreateBegin(__pn_);
+  if (PP.State == PathParser::PS_InRootName)
+    ++PP;
+  if (PP.State == PathParser::PS_InRootDir)
+    return *PP;
+  return {};
+}
+
+string_view_t path::__root_path_raw() const {
+  auto PP = PathParser::CreateBegin(__pn_);
+  if (PP.State == PathParser::PS_InRootName) {
+    auto NextCh = PP.peek();
+    if (NextCh && *NextCh == '/') {
+      ++PP;
+      return createView(__pn_.data(), &PP.RawEntry.back());
+    }
+    return PP.RawEntry;
+  }
+  if (PP.State == PathParser::PS_InRootDir)
+    return *PP;
+  return {};
+}
+
+static bool ConsumeRootName(PathParser *PP) {
+  static_assert(PathParser::PS_BeforeBegin == 1 &&
+      PathParser::PS_InRootName == 2,
+      "Values for enums are incorrect");
+  while (PP->State <= PathParser::PS_InRootName)
+    ++(*PP);
+  return PP->State == PathParser::PS_AtEnd;
+}
+
+static bool ConsumeRootDir(PathParser* PP) {
+  static_assert(PathParser::PS_BeforeBegin == 1 &&
+                PathParser::PS_InRootName == 2 &&
+                PathParser::PS_InRootDir == 3, "Values for enums are incorrect");
+  while (PP->State <= PathParser::PS_InRootDir)
+    ++(*PP);
+  return PP->State == PathParser::PS_AtEnd;
+}
+
+string_view_t path::__relative_path() const {
+  auto PP = PathParser::CreateBegin(__pn_);
+  if (ConsumeRootDir(&PP))
+    return {};
+  return createView(PP.RawEntry.data(), &__pn_.back());
+}
+
+string_view_t path::__parent_path() const {
+  if (empty())
+    return {};
+  // Determine if we have a root path but not a relative path. In that case
+  // return *this.
+  {
+    auto PP = PathParser::CreateBegin(__pn_);
+    if (ConsumeRootDir(&PP))
+      return __pn_;
+  }
+  // Otherwise remove a single element from the end of the path, and return
+  // a string representing that path
+  {
+    auto PP = PathParser::CreateEnd(__pn_);
+    --PP;
+    if (PP.RawEntry.data() == __pn_.data())
+      return {};
+    --PP;
+    return createView(__pn_.data(), &PP.RawEntry.back());
+  }
+}
+
+string_view_t path::__filename() const {
+  if (empty())
+    return {};
+  {
+    PathParser PP = PathParser::CreateBegin(__pn_);
+    if (ConsumeRootDir(&PP))
+      return {};
+  }
+  return *(--PathParser::CreateEnd(__pn_));
+}
+
+string_view_t path::__stem() const {
+  return parser::separate_filename(__filename()).first;
+}
+
+string_view_t path::__extension() const {
+  return parser::separate_filename(__filename()).second;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// path.gen
+
+enum PathPartKind : unsigned char {
+  PK_None,
+  PK_RootSep,
+  PK_Filename,
+  PK_Dot,
+  PK_DotDot,
+  PK_TrailingSep
+};
+
+static PathPartKind ClassifyPathPart(string_view_t Part) {
+  if (Part.empty())
+    return PK_TrailingSep;
+  if (Part == ".")
+    return PK_Dot;
+  if (Part == "..")
+    return PK_DotDot;
+  if (Part == "/")
+    return PK_RootSep;
+  return PK_Filename;
+}
+
+path path::lexically_normal() const {
+  if (__pn_.empty())
+    return *this;
+
+  using PartKindPair = pair<string_view_t, PathPartKind>;
+  vector<PartKindPair> Parts;
+  // Guess as to how many elements the path has to avoid reallocating.
+  Parts.reserve(32);
+
+  // Track the total size of the parts as we collect them. This allows the
+  // resulting path to reserve the correct amount of memory.
+  size_t NewPathSize = 0;
+  auto AddPart = [&](PathPartKind K, string_view_t P) {
+    NewPathSize += P.size();
+    Parts.emplace_back(P, K);
+  };
+  auto LastPartKind = [&]() {
+    if (Parts.empty())
+      return PK_None;
+    return Parts.back().second;
+  };
+
+  bool MaybeNeedTrailingSep = false;
+  // Build a stack containing the remaining elements of the path, popping off
+  // elements which occur before a '..' entry.
+  for (auto PP = PathParser::CreateBegin(__pn_); PP; ++PP) {
+    auto Part = *PP;
+    PathPartKind Kind = ClassifyPathPart(Part);
+    switch (Kind) {
+    case PK_Filename:
+    case PK_RootSep: {
+      // Add all non-dot and non-dot-dot elements to the stack of elements.
+      AddPart(Kind, Part);
+      MaybeNeedTrailingSep = false;
+      break;
+    }
+    case PK_DotDot: {
+      // Only push a ".." element if there are no elements preceding the "..",
+      // or if the preceding element is itself "..".
+      auto LastKind = LastPartKind();
+      if (LastKind == PK_Filename) {
+        NewPathSize -= Parts.back().first.size();
+        Parts.pop_back();
+      } else if (LastKind != PK_RootSep)
+        AddPart(PK_DotDot, "..");
+      MaybeNeedTrailingSep = LastKind == PK_Filename;
+      break;
+    }
+    case PK_Dot:
+    case PK_TrailingSep: {
+      MaybeNeedTrailingSep = true;
+      break;
+    }
+    case PK_None:
+      _LIBCPP_UNREACHABLE();
+    }
+  }
+  // [fs.path.generic]p6.8: If the path is empty, add a dot.
+  if (Parts.empty())
+    return ".";
+
+  // [fs.path.generic]p6.7: If the last filename is dot-dot, remove any
+  // trailing directory-separator.
+  bool NeedTrailingSep = MaybeNeedTrailingSep && LastPartKind() == PK_Filename;
+
+  path Result;
+  Result.__pn_.reserve(Parts.size() + NewPathSize + NeedTrailingSep);
+  for (auto& PK : Parts)
+    Result /= PK.first;
+
+  if (NeedTrailingSep)
+    Result /= "";
+
+  return Result;
+}
+
+static int DetermineLexicalElementCount(PathParser PP) {
+  int Count = 0;
+  for (; PP; ++PP) {
+    auto Elem = *PP;
+    if (Elem == "..")
+      --Count;
+    else if (Elem != "." && Elem != "")
+      ++Count;
+  }
+  return Count;
+}
+
+path path::lexically_relative(const path& base) const {
+  { // perform root-name/root-directory mismatch checks
+    auto PP = PathParser::CreateBegin(__pn_);
+    auto PPBase = PathParser::CreateBegin(base.__pn_);
+    auto CheckIterMismatchAtBase = [&]() {
+      return PP.State != PPBase.State &&
+             (PP.inRootPath() || PPBase.inRootPath());
+    };
+    if (PP.inRootName() && PPBase.inRootName()) {
+      if (*PP != *PPBase)
+        return {};
+    } else if (CheckIterMismatchAtBase())
+      return {};
+
+    if (PP.inRootPath())
+      ++PP;
+    if (PPBase.inRootPath())
+      ++PPBase;
+    if (CheckIterMismatchAtBase())
+      return {};
+  }
+
+  // Find the first mismatching element
+  auto PP = PathParser::CreateBegin(__pn_);
+  auto PPBase = PathParser::CreateBegin(base.__pn_);
+  while (PP && PPBase && PP.State == PPBase.State && *PP == *PPBase) {
+    ++PP;
+    ++PPBase;
+  }
+
+  // If there is no mismatch, return ".".
+  if (!PP && !PPBase)
+    return ".";
+
+  // Otherwise, determine the number of elements, 'n', which are not dot or
+  // dot-dot minus the number of dot-dot elements.
+  int ElemCount = DetermineLexicalElementCount(PPBase);
+  if (ElemCount < 0)
+    return {};
+
+  // if n == 0 and (a == end() || a->empty()), returns path("."); otherwise
+  if (ElemCount == 0 && (PP.atEnd() || *PP == ""))
+    return ".";
+
+  // return a path constructed with 'n' dot-dot elements, followed by the the
+  // elements of '*this' after the mismatch.
+  path Result;
+  // FIXME: Reserve enough room in Result that it won't have to re-allocate.
+  while (ElemCount--)
+    Result /= "..";
+  for (; PP; ++PP)
+    Result /= *PP;
+  return Result;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// path.comparisons
+static int CompareRootName(PathParser *LHS, PathParser *RHS) {
+  if (!LHS->inRootName() && !RHS->inRootName())
+    return 0;
+
+  auto GetRootName = [](PathParser *Parser) -> string_view_t {
+    return Parser->inRootName() ? **Parser : "";
+  };
+  int res = GetRootName(LHS).compare(GetRootName(RHS));
+  ConsumeRootName(LHS);
+  ConsumeRootName(RHS);
+  return res;
+}
+
+static int CompareRootDir(PathParser *LHS, PathParser *RHS) {
+  if (!LHS->inRootDir() && RHS->inRootDir())
+    return -1;
+  else if (LHS->inRootDir() && !RHS->inRootDir())
+    return 1;
+  else {
+    ConsumeRootDir(LHS);
+    ConsumeRootDir(RHS);
+    return 0;
+  }
+}
+
+static int CompareRelative(PathParser *LHSPtr, PathParser *RHSPtr) {
+  auto &LHS = *LHSPtr;
+  auto &RHS = *RHSPtr;
+
+  int res;
+  while (LHS && RHS) {
+    if ((res = (*LHS).compare(*RHS)) != 0)
+      return res;
+    ++LHS;
+    ++RHS;
+  }
+  return 0;
+}
+
+static int CompareEndState(PathParser *LHS, PathParser *RHS) {
+  if (LHS->atEnd() && !RHS->atEnd())
+    return -1;
+  else if (!LHS->atEnd() && RHS->atEnd())
+    return 1;
+  return 0;
+}
+
+int path::__compare(string_view_t __s) const {
+  auto LHS = PathParser::CreateBegin(__pn_);
+  auto RHS = PathParser::CreateBegin(__s);
+  int res;
+
+  if ((res = CompareRootName(&LHS, &RHS)) != 0)
+    return res;
+
+  if ((res = CompareRootDir(&LHS, &RHS)) != 0)
+    return res;
+
+  if ((res = CompareRelative(&LHS, &RHS)) != 0)
+    return res;
+
+  return CompareEndState(&LHS, &RHS);
+}
+
+////////////////////////////////////////////////////////////////////////////
+// path.nonmembers
+size_t hash_value(const path& __p) noexcept {
+  auto PP = PathParser::CreateBegin(__p.native());
+  size_t hash_value = 0;
+  hash<string_view_t> hasher;
+  while (PP) {
+    hash_value = __hash_combine(hash_value, hasher(*PP));
+    ++PP;
+  }
+  return hash_value;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// path.itr
+path::iterator path::begin() const {
+  auto PP = PathParser::CreateBegin(__pn_);
+  iterator it;
+  it.__path_ptr_ = this;
+  it.__state_ = static_cast<path::iterator::_ParserState>(PP.State);
+  it.__entry_ = PP.RawEntry;
+  it.__stashed_elem_.__assign_view(*PP);
+  return it;
+}
+
+path::iterator path::end() const {
+  iterator it{};
+  it.__state_ = path::iterator::_AtEnd;
+  it.__path_ptr_ = this;
+  return it;
+}
+
+path::iterator& path::iterator::__increment() {
+  PathParser PP(__path_ptr_->native(), __entry_, __state_);
+  ++PP;
+  __state_ = static_cast<_ParserState>(PP.State);
+  __entry_ = PP.RawEntry;
+  __stashed_elem_.__assign_view(*PP);
+  return *this;
+}
+
+path::iterator& path::iterator::__decrement() {
+  PathParser PP(__path_ptr_->native(), __entry_, __state_);
+  --PP;
+  __state_ = static_cast<_ParserState>(PP.State);
+  __entry_ = PP.RawEntry;
+  __stashed_elem_.__assign_view(*PP);
+  return *this;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+//                           directory entry definitions
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _LIBCPP_WIN32API
+error_code directory_entry::__do_refresh() noexcept {
+  __data_.__reset();
+  error_code failure_ec;
+
+  StatT full_st;
+  file_status st = detail::posix_lstat(__p_, full_st, &failure_ec);
+  if (!status_known(st)) {
+    __data_.__reset();
+    return failure_ec;
+  }
+
+  if (!_VSTD_FS::exists(st) || !_VSTD_FS::is_symlink(st)) {
+    __data_.__cache_type_ = directory_entry::_RefreshNonSymlink;
+    __data_.__type_ = st.type();
+    __data_.__non_sym_perms_ = st.permissions();
+  } else { // we have a symlink
+    __data_.__sym_perms_ = st.permissions();
+    // Get the information about the linked entity.
+    // Ignore errors from stat, since we don't want errors regarding symlink
+    // resolution to be reported to the user.
+    error_code ignored_ec;
+    st = detail::posix_stat(__p_, full_st, &ignored_ec);
+
+    __data_.__type_ = st.type();
+    __data_.__non_sym_perms_ = st.permissions();
+
+    // If we failed to resolve the link, then only partially populate the
+    // cache.
+    if (!status_known(st)) {
+      __data_.__cache_type_ = directory_entry::_RefreshSymlinkUnresolved;
+      return error_code{};
+    }
+    // Otherwise, we resolved the link, potentially as not existing.
+    // That's OK.
+    __data_.__cache_type_ = directory_entry::_RefreshSymlink;
+  }
+
+  if (_VSTD_FS::is_regular_file(st))
+    __data_.__size_ = static_cast<uintmax_t>(full_st.st_size);
+
+  if (_VSTD_FS::exists(st)) {
+    __data_.__nlink_ = static_cast<uintmax_t>(full_st.st_nlink);
+
+    // Attempt to extract the mtime, and fail if it's not representable using
+    // file_time_type. For now we ignore the error, as we'll report it when
+    // the value is actually used.
+    error_code ignored_ec;
+    __data_.__write_time_ =
+        __extract_last_write_time(__p_, full_st, &ignored_ec);
+  }
+
+  return failure_ec;
+}
+#else
+error_code directory_entry::__do_refresh() noexcept {
+  __data_.__reset();
+  error_code failure_ec;
+
+  file_status st = _VSTD_FS::symlink_status(__p_, failure_ec);
+  if (!status_known(st)) {
+    __data_.__reset();
+    return failure_ec;
+  }
+
+  if (!_VSTD_FS::exists(st) || !_VSTD_FS::is_symlink(st)) {
+    __data_.__cache_type_ = directory_entry::_RefreshNonSymlink;
+    __data_.__type_ = st.type();
+    __data_.__non_sym_perms_ = st.permissions();
+  } else { // we have a symlink
+    __data_.__sym_perms_ = st.permissions();
+    // Get the information about the linked entity.
+    // Ignore errors from stat, since we don't want errors regarding symlink
+    // resolution to be reported to the user.
+    error_code ignored_ec;
+    st = _VSTD_FS::status(__p_, ignored_ec);
+
+    __data_.__type_ = st.type();
+    __data_.__non_sym_perms_ = st.permissions();
+
+    // If we failed to resolve the link, then only partially populate the
+    // cache.
+    if (!status_known(st)) {
+      __data_.__cache_type_ = directory_entry::_RefreshSymlinkUnresolved;
+      return error_code{};
+    }
+    __data_.__cache_type_ = directory_entry::_RefreshSymlink;
+  }
+
+  // FIXME: This is currently broken, and the implementation only a placeholder.
+  // We need to cache last_write_time, file_size, and hard_link_count here before
+  // the implementation actually works.
+
+  return failure_ec;
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM
diff --git a/lib/libcxx/src/functional.cpp b/lib/libcxx/src/functional.cpp
new file mode 100644
index 0000000000..555d2c53f2
--- /dev/null
+++ b/lib/libcxx/src/functional.cpp
@@ -0,0 +1,25 @@
+//===----------------------- functional.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "functional"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+bad_function_call::~bad_function_call() _NOEXCEPT
+{
+}
+
+const char*
+bad_function_call::what() const _NOEXCEPT
+{
+    return "std::bad_function_call";
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/future.cpp b/lib/libcxx/src/future.cpp
new file mode 100644
index 0000000000..58d0b4c247
--- /dev/null
+++ b/lib/libcxx/src/future.cpp
@@ -0,0 +1,277 @@
+//===------------------------- future.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include "future"
+#include "string"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+class _LIBCPP_HIDDEN __future_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const _NOEXCEPT;
+    virtual string message(int ev) const;
+};
+
+const char*
+__future_error_category::name() const _NOEXCEPT
+{
+    return "future";
+}
+
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wswitch"
+#elif defined(__GNUC__) || defined(__GNUG__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wswitch"
+#endif
+
+string
+__future_error_category::message(int ev) const
+{
+    switch (static_cast<future_errc>(ev))
+    {
+    case future_errc(0):  // For backwards compatibility with C++11 (LWG 2056)
+    case future_errc::broken_promise:
+        return string("The associated promise has been destructed prior "
+                      "to the associated state becoming ready.");
+    case future_errc::future_already_retrieved:
+        return string("The future has already been retrieved from "
+                      "the promise or packaged_task.");
+    case future_errc::promise_already_satisfied:
+        return string("The state of the promise has already been set.");
+    case future_errc::no_state:
+        return string("Operation not permitted on an object without "
+                      "an associated state.");
+    }
+    return string("unspecified future_errc value\n");
+}
+
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#elif defined(__GNUC__) || defined(__GNUG__)
+#pragma GCC diagnostic pop
+#endif
+
+const error_category&
+future_category() _NOEXCEPT
+{
+    static __future_error_category __f;
+    return __f;
+}
+
+future_error::future_error(error_code __ec)
+    : logic_error(__ec.message()),
+      __ec_(__ec)
+{
+}
+
+future_error::~future_error() _NOEXCEPT
+{
+}
+
+void
+__assoc_sub_state::__on_zero_shared() _NOEXCEPT
+{
+    delete this;
+}
+
+void
+__assoc_sub_state::set_value()
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __state_ |= __constructed | ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::set_value_at_thread_exit()
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __state_ |= __constructed;
+    __thread_local_data()->__make_ready_at_thread_exit(this);
+}
+
+void
+__assoc_sub_state::set_exception(exception_ptr __p)
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __exception_ = __p;
+    __state_ |= ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::set_exception_at_thread_exit(exception_ptr __p)
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __exception_ = __p;
+    __thread_local_data()->__make_ready_at_thread_exit(this);
+}
+
+void
+__assoc_sub_state::__make_ready()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __state_ |= ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::copy()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __sub_wait(__lk);
+    if (__exception_ != nullptr)
+        rethrow_exception(__exception_);
+}
+
+void
+__assoc_sub_state::wait()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __sub_wait(__lk);
+}
+
+void
+__assoc_sub_state::__sub_wait(unique_lock<mutex>& __lk)
+{
+    if (!__is_ready())
+    {
+        if (__state_ & static_cast<unsigned>(deferred))
+        {
+            __state_ &= ~static_cast<unsigned>(deferred);
+            __lk.unlock();
+            __execute();
+        }
+        else
+            while (!__is_ready())
+                __cv_.wait(__lk);
+    }
+}
+
+void
+__assoc_sub_state::__execute()
+{
+    __throw_future_error(future_errc::no_state);
+}
+
+future<void>::future(__assoc_sub_state* __state)
+    : __state_(__state)
+{
+    __state_->__attach_future();
+}
+
+future<void>::~future()
+{
+    if (__state_)
+        __state_->__release_shared();
+}
+
+void
+future<void>::get()
+{
+    unique_ptr<__shared_count, __release_shared_count> __(__state_);
+    __assoc_sub_state* __s = __state_;
+    __state_ = nullptr;
+    __s->copy();
+}
+
+promise<void>::promise()
+    : __state_(new __assoc_sub_state)
+{
+}
+
+promise<void>::~promise()
+{
+    if (__state_)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        if (!__state_->__has_value() && __state_->use_count() > 1)
+            __state_->set_exception(make_exception_ptr(
+                      future_error(make_error_code(future_errc::broken_promise))
+                                                      ));
+#endif // _LIBCPP_NO_EXCEPTIONS
+        __state_->__release_shared();
+    }
+}
+
+future<void>
+promise<void>::get_future()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    return future<void>(__state_);
+}
+
+void
+promise<void>::set_value()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_value();
+}
+
+void
+promise<void>::set_exception(exception_ptr __p)
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_exception(__p);
+}
+
+void
+promise<void>::set_value_at_thread_exit()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_value_at_thread_exit();
+}
+
+void
+promise<void>::set_exception_at_thread_exit(exception_ptr __p)
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_exception_at_thread_exit(__p);
+}
+
+shared_future<void>::~shared_future()
+{
+    if (__state_)
+        __state_->__release_shared();
+}
+
+shared_future<void>&
+shared_future<void>::operator=(const shared_future& __rhs)
+{
+    if (__rhs.__state_)
+        __rhs.__state_->__add_shared();
+    if (__state_)
+        __state_->__release_shared();
+    __state_ = __rhs.__state_;
+    return *this;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS
diff --git a/lib/libcxx/src/hash.cpp b/lib/libcxx/src/hash.cpp
new file mode 100644
index 0000000000..89bb736c86
--- /dev/null
+++ b/lib/libcxx/src/hash.cpp
@@ -0,0 +1,561 @@
+//===-------------------------- hash.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__hash_table"
+#include "algorithm"
+#include "stdexcept"
+#include "type_traits"
+
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wtautological-constant-out-of-range-compare"
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+// handle all next_prime(i) for i in [1, 210), special case 0
+const unsigned small_primes[] =
+{
+    0,
+    2,
+    3,
+    5,
+    7,
+    11,
+    13,
+    17,
+    19,
+    23,
+    29,
+    31,
+    37,
+    41,
+    43,
+    47,
+    53,
+    59,
+    61,
+    67,
+    71,
+    73,
+    79,
+    83,
+    89,
+    97,
+    101,
+    103,
+    107,
+    109,
+    113,
+    127,
+    131,
+    137,
+    139,
+    149,
+    151,
+    157,
+    163,
+    167,
+    173,
+    179,
+    181,
+    191,
+    193,
+    197,
+    199,
+    211
+};
+
+// potential primes = 210*k + indices[i], k >= 1
+//   these numbers are not divisible by 2, 3, 5 or 7
+//   (or any integer 2 <= j <= 10 for that matter).
+const unsigned indices[] =
+{
+    1,
+    11,
+    13,
+    17,
+    19,
+    23,
+    29,
+    31,
+    37,
+    41,
+    43,
+    47,
+    53,
+    59,
+    61,
+    67,
+    71,
+    73,
+    79,
+    83,
+    89,
+    97,
+    101,
+    103,
+    107,
+    109,
+    113,
+    121,
+    127,
+    131,
+    137,
+    139,
+    143,
+    149,
+    151,
+    157,
+    163,
+    167,
+    169,
+    173,
+    179,
+    181,
+    187,
+    191,
+    193,
+    197,
+    199,
+    209
+};
+
+}
+
+// Returns:  If n == 0, returns 0.  Else returns the lowest prime number that
+// is greater than or equal to n.
+//
+// The algorithm creates a list of small primes, plus an open-ended list of
+// potential primes.  All prime numbers are potential prime numbers.  However
+// some potential prime numbers are not prime.  In an ideal world, all potential
+// prime numbers would be prime.  Candidate prime numbers are chosen as the next
+// highest potential prime.  Then this number is tested for prime by dividing it
+// by all potential prime numbers less than the sqrt of the candidate.
+//
+// This implementation defines potential primes as those numbers not divisible
+// by 2, 3, 5, and 7.  Other (common) implementations define potential primes
+// as those not divisible by 2.  A few other implementations define potential
+// primes as those not divisible by 2 or 3.  By raising the number of small
+// primes which the potential prime is not divisible by, the set of potential
+// primes more closely approximates the set of prime numbers.  And thus there
+// are fewer potential primes to search, and fewer potential primes to divide
+// against.
+
+template <size_t _Sz = sizeof(size_t)>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<_Sz == 4, void>::type
+__check_for_overflow(size_t N)
+{
+    if (N > 0xFFFFFFFB)
+        __throw_overflow_error("__next_prime overflow");
+}
+
+template <size_t _Sz = sizeof(size_t)>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<_Sz == 8, void>::type
+__check_for_overflow(size_t N)
+{
+    if (N > 0xFFFFFFFFFFFFFFC5ull)
+        __throw_overflow_error("__next_prime overflow");
+}
+
+size_t
+__next_prime(size_t n)
+{
+    const size_t L = 210;
+    const size_t N = sizeof(small_primes) / sizeof(small_primes[0]);
+    // If n is small enough, search in small_primes
+    if (n <= small_primes[N-1])
+        return *std::lower_bound(small_primes, small_primes + N, n);
+    // Else n > largest small_primes
+    // Check for overflow
+    __check_for_overflow(n);
+    // Start searching list of potential primes: L * k0 + indices[in]
+    const size_t M = sizeof(indices) / sizeof(indices[0]);
+    // Select first potential prime >= n
+    //   Known a-priori n >= L
+    size_t k0 = n / L;
+    size_t in = static_cast<size_t>(std::lower_bound(indices, indices + M, n - k0 * L)
+                                    - indices);
+    n = L * k0 + indices[in];
+    while (true)
+    {
+        // Divide n by all primes or potential primes (i) until:
+        //    1.  The division is even, so try next potential prime.
+        //    2.  The i > sqrt(n), in which case n is prime.
+        // It is known a-priori that n is not divisible by 2, 3, 5 or 7,
+        //    so don't test those (j == 5 ->  divide by 11 first).  And the
+        //    potential primes start with 211, so don't test against the last
+        //    small prime.
+        for (size_t j = 5; j < N - 1; ++j)
+        {
+            const std::size_t p = small_primes[j];
+            const std::size_t q = n / p;
+            if (q < p)
+                return n;
+            if (n == q * p)
+                goto next;
+        }
+        // n wasn't divisible by small primes, try potential primes
+        {
+            size_t i = 211;
+            while (true)
+            {
+                std::size_t q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 10;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 8;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 8;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 10;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                // This will loop i to the next "plane" of potential primes
+                i += 2;
+            }
+        }
+next:
+        // n is not prime.  Increment n to next potential prime.
+        if (++in == M)
+        {
+            ++k0;
+            in = 0;
+        }
+        n = L * k0 + indices[in];
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/include/apple_availability.h b/lib/libcxx/src/include/apple_availability.h
new file mode 100644
index 0000000000..0091138170
--- /dev/null
+++ b/lib/libcxx/src/include/apple_availability.h
@@ -0,0 +1,51 @@
+//===------------------------ apple_availability.h ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H
+#define _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H
+
+#if defined(__APPLE__)
+
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 101300
+#define _LIBCPP_USE_UTIMENSAT
+#endif
+#elif defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ >= 110000
+#define _LIBCPP_USE_UTIMENSAT
+#endif
+#elif defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ >= 110000
+#define _LIBCPP_USE_UTIMENSAT
+#endif
+#elif defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 40000
+#define _LIBCPP_USE_UTIMENSAT
+#endif
+#endif // __ENVIRONMENT_.*_VERSION_MIN_REQUIRED__
+
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 101200
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+#elif defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ >= 100000
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+#elif defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ >= 100000
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+#elif defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 30000
+#define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+#endif // __ENVIRONMENT_.*_VERSION_MIN_REQUIRED__
+
+#endif // __APPLE__
+
+#endif // _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H
diff --git a/lib/libcxx/src/include/atomic_support.h b/lib/libcxx/src/include/atomic_support.h
new file mode 100644
index 0000000000..43c1a00234
--- /dev/null
+++ b/lib/libcxx/src/include/atomic_support.h
@@ -0,0 +1,176 @@
+//===----------------------------------------------------------------------===////
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===////
+
+#ifndef ATOMIC_SUPPORT_H
+#define ATOMIC_SUPPORT_H
+
+#include "__config"
+#include "memory" // for __libcpp_relaxed_load
+
+#if defined(__clang__) && __has_builtin(__atomic_load_n)             \
+                       && __has_builtin(__atomic_store_n)            \
+                       && __has_builtin(__atomic_add_fetch)          \
+                       && __has_builtin(__atomic_exchange_n)         \
+                       && __has_builtin(__atomic_compare_exchange_n) \
+                       && defined(__ATOMIC_RELAXED)                  \
+                       && defined(__ATOMIC_CONSUME)                  \
+                       && defined(__ATOMIC_ACQUIRE)                  \
+                       && defined(__ATOMIC_RELEASE)                  \
+                       && defined(__ATOMIC_ACQ_REL)                  \
+                       && defined(__ATOMIC_SEQ_CST)
+#   define _LIBCPP_HAS_ATOMIC_BUILTINS
+#elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407
+#   define _LIBCPP_HAS_ATOMIC_BUILTINS
+#endif
+
+#if !defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
+# if defined(_LIBCPP_WARNING)
+    _LIBCPP_WARNING("Building libc++ without __atomic builtins is unsupported")
+# else
+#   warning Building libc++ without __atomic builtins is unsupported
+# endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+#if defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed = __ATOMIC_RELAXED,
+    _AO_Consume = __ATOMIC_CONSUME,
+    _AO_Acquire = __ATOMIC_ACQUIRE,
+    _AO_Release = __ATOMIC_RELEASE,
+    _AO_Acq_Rel = __ATOMIC_ACQ_REL,
+    _AO_Seq     = __ATOMIC_SEQ_CST
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int __order = _AO_Seq)
+{
+    __atomic_store_n(__dest, __val, __order);
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    __atomic_store_n(__dest, __val, _AO_Relaxed);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int __order = _AO_Seq)
+{
+    return __atomic_load_n(__val, __order);
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int __order = _AO_Seq)
+{
+    return __atomic_add_fetch(__val, __a, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int __order = _AO_Seq)
+{
+    return __atomic_exchange_n(__target, __value, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int __success_order = _AO_Seq,
+    int __fail_order = _AO_Seq)
+{
+    return __atomic_compare_exchange_n(__val, __expected, __after, true,
+                                       __success_order, __fail_order);
+}
+
+#else // _LIBCPP_HAS_NO_THREADS
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed,
+    _AO_Consume,
+    _AO_Acquire,
+    _AO_Release,
+    _AO_Acq_Rel,
+    _AO_Seq
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int = 0)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int = 0)
+{
+    return *__val;
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int = 0)
+{
+    return *__val += __a;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int __order = _AO_Seq)
+{
+    _ValueType old = *__target;
+    *__target = __value;
+    return old;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int = 0, int = 0)
+{
+    if (*__val == *__expected) {
+        *__val = __after;
+        return true;
+    }
+    *__expected = *__val;
+    return false;
+}
+
+#endif // _LIBCPP_HAS_NO_THREADS
+
+} // end namespace
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // ATOMIC_SUPPORT_H
diff --git a/lib/libcxx/src/include/config_elast.h b/lib/libcxx/src/include/config_elast.h
new file mode 100644
index 0000000000..501cbc4ffe
--- /dev/null
+++ b/lib/libcxx/src/include/config_elast.h
@@ -0,0 +1,41 @@
+//===----------------------- config_elast.h -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_CONFIG_ELAST
+#define _LIBCPP_CONFIG_ELAST
+
+#include <__config>
+
+#if defined(_LIBCPP_MSVCRT_LIKE)
+#include <stdlib.h>
+#else
+#include <errno.h>
+#endif
+
+#if defined(ELAST)
+#define _LIBCPP_ELAST ELAST
+#elif defined(_NEWLIB_VERSION)
+#define _LIBCPP_ELAST __ELASTERROR
+#elif defined(__Fuchsia__)
+// No _LIBCPP_ELAST needed on Fuchsia
+#elif defined(__wasi__)
+// No _LIBCPP_ELAST needed on WASI
+#elif defined(__linux__) || defined(_LIBCPP_HAS_MUSL_LIBC)
+#define _LIBCPP_ELAST 4095
+#elif defined(__APPLE__)
+// No _LIBCPP_ELAST needed on Apple
+#elif defined(__sun__)
+#define _LIBCPP_ELAST ESTALE
+#elif defined(_LIBCPP_MSVCRT_LIKE)
+#define _LIBCPP_ELAST (_sys_nerr - 1)
+#else
+// Warn here so that the person doing the libcxx port has an easier time:
+#warning ELAST for this platform not yet implemented
+#endif
+
+#endif // _LIBCPP_CONFIG_ELAST
diff --git a/lib/libcxx/src/include/refstring.h b/lib/libcxx/src/include/refstring.h
new file mode 100644
index 0000000000..e464b79ba8
--- /dev/null
+++ b/lib/libcxx/src/include/refstring.h
@@ -0,0 +1,127 @@
+//===------------------------ __refstring ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_REFSTRING_H
+#define _LIBCPP_REFSTRING_H
+
+#include <__config>
+#include <stdexcept>
+#include <cstddef>
+#include <cstring>
+#ifdef __APPLE__
+#include <dlfcn.h>
+#include <mach-o/dyld.h>
+#endif
+#include "atomic_support.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace __refstring_imp { namespace {
+typedef int count_t;
+
+struct _Rep_base {
+    std::size_t len;
+    std::size_t cap;
+    count_t     count;
+};
+
+inline _Rep_base* rep_from_data(const char *data_) noexcept {
+    char *data = const_cast<char *>(data_);
+    return reinterpret_cast<_Rep_base *>(data - sizeof(_Rep_base));
+}
+
+inline char * data_from_rep(_Rep_base *rep) noexcept {
+    char *data = reinterpret_cast<char *>(rep);
+    return data + sizeof(*rep);
+}
+
+#if defined(__APPLE__)
+inline
+const char* compute_gcc_empty_string_storage() _NOEXCEPT
+{
+    void* handle = dlopen("/usr/lib/libstdc++.6.dylib", RTLD_NOLOAD);
+    if (handle == nullptr)
+        return nullptr;
+    void* sym = dlsym(handle, "_ZNSs4_Rep20_S_empty_rep_storageE");
+    if (sym == nullptr)
+        return nullptr;
+    return data_from_rep(reinterpret_cast<_Rep_base *>(sym));
+}
+
+inline
+const char*
+get_gcc_empty_string_storage() _NOEXCEPT
+{
+    static const char* p = compute_gcc_empty_string_storage();
+    return p;
+}
+#endif
+
+}} // namespace __refstring_imp
+
+using namespace __refstring_imp;
+
+inline
+__libcpp_refstring::__libcpp_refstring(const char* msg) {
+    std::size_t len = strlen(msg);
+    _Rep_base* rep = static_cast<_Rep_base *>(::operator new(sizeof(*rep) + len + 1));
+    rep->len = len;
+    rep->cap = len;
+    rep->count = 0;
+    char *data = data_from_rep(rep);
+    std::memcpy(data, msg, len + 1);
+    __imp_ = data;
+}
+
+inline
+__libcpp_refstring::__libcpp_refstring(const __libcpp_refstring &s) _NOEXCEPT
+    : __imp_(s.__imp_)
+{
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+}
+
+inline
+__libcpp_refstring& __libcpp_refstring::operator=(__libcpp_refstring const& s) _NOEXCEPT {
+    bool adjust_old_count = __uses_refcount();
+    struct _Rep_base *old_rep = rep_from_data(__imp_);
+    __imp_ = s.__imp_;
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+    if (adjust_old_count)
+    {
+        if (__libcpp_atomic_add(&old_rep->count, count_t(-1)) < 0)
+        {
+            ::operator delete(old_rep);
+        }
+    }
+    return *this;
+}
+
+inline
+__libcpp_refstring::~__libcpp_refstring() {
+    if (__uses_refcount()) {
+        _Rep_base* rep = rep_from_data(__imp_);
+        if (__libcpp_atomic_add(&rep->count, count_t(-1)) < 0) {
+            ::operator delete(rep);
+        }
+    }
+}
+
+inline
+bool __libcpp_refstring::__uses_refcount() const {
+#ifdef __APPLE__
+    return __imp_ != get_gcc_empty_string_storage();
+#else
+    return true;
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif //_LIBCPP_REFSTRING_H
diff --git a/lib/libcxx/src/ios.cpp b/lib/libcxx/src/ios.cpp
new file mode 100644
index 0000000000..2dc84be828
--- /dev/null
+++ b/lib/libcxx/src/ios.cpp
@@ -0,0 +1,457 @@
+//===-------------------------- ios.cpp -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+
+#include "ios"
+
+#include <stdlib.h>
+
+#include "__locale"
+#include "algorithm"
+#include "include/config_elast.h"
+#include "istream"
+#include "limits"
+#include "memory"
+#include "new"
+#include "streambuf"
+#include "string"
+#include "__undef_macros"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
+
+class _LIBCPP_HIDDEN __iostream_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const _NOEXCEPT;
+    virtual string message(int ev) const;
+};
+
+const char*
+__iostream_category::name() const _NOEXCEPT
+{
+    return "iostream";
+}
+
+string
+__iostream_category::message(int ev) const
+{
+    if (ev != static_cast<int>(io_errc::stream)
+#ifdef _LIBCPP_ELAST
+        && ev <= _LIBCPP_ELAST
+#endif  // _LIBCPP_ELAST
+        )
+        return __do_message::message(ev);
+    return string("unspecified iostream_category error");
+}
+
+const error_category&
+iostream_category() _NOEXCEPT
+{
+    static __iostream_category s;
+    return s;
+}
+
+// ios_base::failure
+
+ios_base::failure::failure(const string& msg, const error_code& ec)
+    : system_error(ec, msg)
+{
+}
+
+ios_base::failure::failure(const char* msg, const error_code& ec)
+    : system_error(ec, msg)
+{
+}
+
+ios_base::failure::~failure() throw()
+{
+}
+
+// ios_base locale
+
+const ios_base::fmtflags ios_base::boolalpha;
+const ios_base::fmtflags ios_base::dec;
+const ios_base::fmtflags ios_base::fixed;
+const ios_base::fmtflags ios_base::hex;
+const ios_base::fmtflags ios_base::internal;
+const ios_base::fmtflags ios_base::left;
+const ios_base::fmtflags ios_base::oct;
+const ios_base::fmtflags ios_base::right;
+const ios_base::fmtflags ios_base::scientific;
+const ios_base::fmtflags ios_base::showbase;
+const ios_base::fmtflags ios_base::showpoint;
+const ios_base::fmtflags ios_base::showpos;
+const ios_base::fmtflags ios_base::skipws;
+const ios_base::fmtflags ios_base::unitbuf;
+const ios_base::fmtflags ios_base::uppercase;
+const ios_base::fmtflags ios_base::adjustfield;
+const ios_base::fmtflags ios_base::basefield;
+const ios_base::fmtflags ios_base::floatfield;
+
+const ios_base::iostate ios_base::badbit;
+const ios_base::iostate ios_base::eofbit;
+const ios_base::iostate ios_base::failbit;
+const ios_base::iostate ios_base::goodbit;
+
+const ios_base::openmode ios_base::app;
+const ios_base::openmode ios_base::ate;
+const ios_base::openmode ios_base::binary;
+const ios_base::openmode ios_base::in;
+const ios_base::openmode ios_base::out;
+const ios_base::openmode ios_base::trunc;
+
+void
+ios_base::__call_callbacks(event ev)
+{
+    for (size_t i = __event_size_; i;)
+    {
+        --i;
+        __fn_[i](ev, *this, __index_[i]);
+    }
+}
+
+// locale
+
+locale
+ios_base::imbue(const locale& newloc)
+{
+    static_assert(sizeof(locale) == sizeof(__loc_), "");
+    locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
+    locale oldloc = loc_storage;
+    loc_storage = newloc;
+    __call_callbacks(imbue_event);
+    return oldloc;
+}
+
+locale
+ios_base::getloc() const
+{
+    const locale& loc_storage = *reinterpret_cast<const locale*>(&__loc_);
+    return loc_storage;
+}
+
+// xalloc
+#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+atomic<int> ios_base::__xindex_ = ATOMIC_VAR_INIT(0);
+#else
+int ios_base::__xindex_ = 0;
+#endif
+
+template <typename _Tp>
+static size_t __ios_new_cap(size_t __req_size, size_t __current_cap)
+{ // Precondition: __req_size > __current_cap
+	const size_t mx = std::numeric_limits<size_t>::max() / sizeof(_Tp);
+	if (__req_size < mx/2)
+		return _VSTD::max(2 * __current_cap, __req_size);
+	else
+		return mx;
+}
+
+int
+ios_base::xalloc()
+{
+    return __xindex_++;
+}
+
+long&
+ios_base::iword(int index)
+{
+    size_t req_size = static_cast<size_t>(index)+1;
+    if (req_size > __iarray_cap_)
+    {
+        size_t newcap = __ios_new_cap<long>(req_size, __iarray_cap_);
+        long* iarray = static_cast<long*>(realloc(__iarray_, newcap * sizeof(long)));
+        if (iarray == 0)
+        {
+            setstate(badbit);
+            static long error;
+            error = 0;
+            return error;
+        }
+        __iarray_ = iarray;
+        for (long* p = __iarray_ + __iarray_size_; p < __iarray_ + newcap; ++p)
+            *p = 0;
+        __iarray_cap_ = newcap;
+    }
+    __iarray_size_ = max<size_t>(__iarray_size_, req_size);
+    return __iarray_[index];
+}
+
+void*&
+ios_base::pword(int index)
+{
+    size_t req_size = static_cast<size_t>(index)+1;
+    if (req_size > __parray_cap_)
+    {
+        size_t newcap = __ios_new_cap<void *>(req_size, __iarray_cap_);
+        void** parray = static_cast<void**>(realloc(__parray_, newcap * sizeof(void *)));
+        if (parray == 0)
+        {
+            setstate(badbit);
+            static void* error;
+            error = 0;
+            return error;
+        }
+        __parray_ = parray;
+        for (void** p = __parray_ + __parray_size_; p < __parray_ + newcap; ++p)
+            *p = 0;
+        __parray_cap_ = newcap;
+    }
+    __parray_size_ = max<size_t>(__parray_size_, req_size);
+    return __parray_[index];
+}
+
+// register_callback
+
+void
+ios_base::register_callback(event_callback fn, int index)
+{
+    size_t req_size = __event_size_ + 1;
+    if (req_size > __event_cap_)
+    {
+        size_t newcap = __ios_new_cap<event_callback>(req_size, __event_cap_);
+        event_callback* fns = static_cast<event_callback*>(realloc(__fn_, newcap * sizeof(event_callback)));
+        if (fns == 0)
+            setstate(badbit);
+        __fn_ = fns;
+        int* indxs = static_cast<int *>(realloc(__index_, newcap * sizeof(int)));
+        if (indxs == 0)
+            setstate(badbit);
+        __index_ = indxs;
+        __event_cap_ = newcap;
+    }
+    __fn_[__event_size_] = fn;
+    __index_[__event_size_] = index;
+    ++__event_size_;
+}
+
+ios_base::~ios_base()
+{
+    __call_callbacks(erase_event);
+    locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
+    loc_storage.~locale();
+    free(__fn_);
+    free(__index_);
+    free(__iarray_);
+    free(__parray_);
+}
+
+// iostate
+
+void
+ios_base::clear(iostate state)
+{
+    if (__rdbuf_)
+        __rdstate_ = state;
+    else
+        __rdstate_ = state | badbit;
+
+    if (((state | (__rdbuf_ ? goodbit : badbit)) & __exceptions_) != 0)
+        __throw_failure("ios_base::clear");
+}
+
+// init
+
+void
+ios_base::init(void* sb)
+{
+    __rdbuf_ = sb;
+    __rdstate_ = __rdbuf_ ? goodbit : badbit;
+    __exceptions_ = goodbit;
+    __fmtflags_ = skipws | dec;
+    __width_ = 0;
+    __precision_ = 6;
+    __fn_ = 0;
+    __index_ = 0;
+    __event_size_ = 0;
+    __event_cap_ = 0;
+    __iarray_ = 0;
+    __iarray_size_ = 0;
+    __iarray_cap_ = 0;
+    __parray_ = 0;
+    __parray_size_ = 0;
+    __parray_cap_ = 0;
+    ::new(&__loc_) locale;
+}
+
+void
+ios_base::copyfmt(const ios_base& rhs)
+{
+    // If we can't acquire the needed resources, throw bad_alloc (can't set badbit)
+    // Don't alter *this until all needed resources are acquired
+    unique_ptr<event_callback, void (*)(void*)> new_callbacks(0, free);
+    unique_ptr<int, void (*)(void*)> new_ints(0, free);
+    unique_ptr<long, void (*)(void*)> new_longs(0, free);
+    unique_ptr<void*, void (*)(void*)> new_pointers(0, free);
+    if (__event_cap_ < rhs.__event_size_)
+    {
+        size_t newesize = sizeof(event_callback) * rhs.__event_size_;
+        new_callbacks.reset(static_cast<event_callback*>(malloc(newesize)));
+        if (!new_callbacks)
+            __throw_bad_alloc();
+
+        size_t newisize = sizeof(int) * rhs.__event_size_;
+        new_ints.reset(static_cast<int *>(malloc(newisize)));
+        if (!new_ints)
+            __throw_bad_alloc();
+    }
+    if (__iarray_cap_ < rhs.__iarray_size_)
+    {
+        size_t newsize = sizeof(long) * rhs.__iarray_size_;
+        new_longs.reset(static_cast<long*>(malloc(newsize)));
+        if (!new_longs)
+            __throw_bad_alloc();
+    }
+    if (__parray_cap_ < rhs.__parray_size_)
+    {
+        size_t newsize = sizeof(void*) * rhs.__parray_size_;
+        new_pointers.reset(static_cast<void**>(malloc(newsize)));
+        if (!new_pointers)
+            __throw_bad_alloc();
+    }
+    // Got everything we need.  Copy everything but __rdstate_, __rdbuf_ and __exceptions_
+    __fmtflags_ = rhs.__fmtflags_;
+    __precision_ = rhs.__precision_;
+    __width_ = rhs.__width_;
+    locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
+    const locale& rhs_loc = *reinterpret_cast<const locale*>(&rhs.__loc_);
+    lhs_loc = rhs_loc;
+    if (__event_cap_ < rhs.__event_size_)
+    {
+        free(__fn_);
+        __fn_ = new_callbacks.release();
+        free(__index_);
+        __index_ = new_ints.release();
+        __event_cap_ = rhs.__event_size_;
+    }
+    for (__event_size_ = 0; __event_size_ < rhs.__event_size_; ++__event_size_)
+    {
+        __fn_[__event_size_] = rhs.__fn_[__event_size_];
+        __index_[__event_size_] = rhs.__index_[__event_size_];
+    }
+    if (__iarray_cap_ < rhs.__iarray_size_)
+    {
+        free(__iarray_);
+        __iarray_ = new_longs.release();
+        __iarray_cap_ = rhs.__iarray_size_;
+    }
+    for (__iarray_size_ = 0; __iarray_size_ < rhs.__iarray_size_; ++__iarray_size_)
+        __iarray_[__iarray_size_] = rhs.__iarray_[__iarray_size_];
+    if (__parray_cap_ < rhs.__parray_size_)
+    {
+        free(__parray_);
+        __parray_ = new_pointers.release();
+        __parray_cap_ = rhs.__parray_size_;
+    }
+    for (__parray_size_ = 0; __parray_size_ < rhs.__parray_size_; ++__parray_size_)
+        __parray_[__parray_size_] = rhs.__parray_[__parray_size_];
+}
+
+void
+ios_base::move(ios_base& rhs)
+{
+    // *this is uninitialized
+    __fmtflags_ = rhs.__fmtflags_;
+    __precision_ = rhs.__precision_;
+    __width_ = rhs.__width_;
+    __rdstate_ = rhs.__rdstate_;
+    __exceptions_ = rhs.__exceptions_;
+    __rdbuf_ = 0;
+    locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
+    ::new(&__loc_) locale(rhs_loc);
+    __fn_ = rhs.__fn_;
+    rhs.__fn_ = 0;
+    __index_ = rhs.__index_;
+    rhs.__index_ = 0;
+    __event_size_ = rhs.__event_size_;
+    rhs.__event_size_ = 0;
+    __event_cap_ = rhs.__event_cap_;
+    rhs.__event_cap_ = 0;
+    __iarray_ = rhs.__iarray_;
+    rhs.__iarray_ = 0;
+    __iarray_size_ = rhs.__iarray_size_;
+    rhs.__iarray_size_ = 0;
+    __iarray_cap_ = rhs.__iarray_cap_;
+    rhs.__iarray_cap_ = 0;
+    __parray_ = rhs.__parray_;
+    rhs.__parray_ = 0;
+    __parray_size_ = rhs.__parray_size_;
+    rhs.__parray_size_ = 0;
+    __parray_cap_ = rhs.__parray_cap_;
+    rhs.__parray_cap_ = 0;
+}
+
+void
+ios_base::swap(ios_base& rhs) _NOEXCEPT
+{
+    _VSTD::swap(__fmtflags_, rhs.__fmtflags_);
+    _VSTD::swap(__precision_, rhs.__precision_);
+    _VSTD::swap(__width_, rhs.__width_);
+    _VSTD::swap(__rdstate_, rhs.__rdstate_);
+    _VSTD::swap(__exceptions_, rhs.__exceptions_);
+    locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
+    locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
+    _VSTD::swap(lhs_loc, rhs_loc);
+    _VSTD::swap(__fn_, rhs.__fn_);
+    _VSTD::swap(__index_, rhs.__index_);
+    _VSTD::swap(__event_size_, rhs.__event_size_);
+    _VSTD::swap(__event_cap_, rhs.__event_cap_);
+    _VSTD::swap(__iarray_, rhs.__iarray_);
+    _VSTD::swap(__iarray_size_, rhs.__iarray_size_);
+    _VSTD::swap(__iarray_cap_, rhs.__iarray_cap_);
+    _VSTD::swap(__parray_, rhs.__parray_);
+    _VSTD::swap(__parray_size_, rhs.__parray_size_);
+    _VSTD::swap(__parray_cap_, rhs.__parray_cap_);
+}
+
+void
+ios_base::__set_badbit_and_consider_rethrow()
+{
+    __rdstate_ |= badbit;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    if (__exceptions_ & badbit)
+        throw;
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+void
+ios_base::__set_failbit_and_consider_rethrow()
+{
+    __rdstate_ |= failbit;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    if (__exceptions_ & failbit)
+        throw;
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+bool
+ios_base::sync_with_stdio(bool sync)
+{
+    static bool previous_state = true;
+    bool r = previous_state;
+    previous_state = sync;
+    return r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/iostream.cpp b/lib/libcxx/src/iostream.cpp
new file mode 100644
index 0000000000..ad1920abc6
--- /dev/null
+++ b/lib/libcxx/src/iostream.cpp
@@ -0,0 +1,159 @@
+//===------------------------ iostream.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__std_stream"
+#include "__locale"
+#include "string"
+#include "new"
+
+#define _str(s) #s
+#define str(s) _str(s)
+#define _LIBCPP_ABI_NAMESPACE_STR str(_LIBCPP_ABI_NAMESPACE)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_HAS_NO_STDIN
+_ALIGNAS_TYPE (istream) _LIBCPP_FUNC_VIS char cin[sizeof(istream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<char> ) static char __cin[sizeof(__stdinbuf <char>)];
+static mbstate_t mb_cin;
+_ALIGNAS_TYPE (wistream) _LIBCPP_FUNC_VIS char wcin[sizeof(wistream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<wchar_t> ) static char __wcin[sizeof(__stdinbuf <wchar_t>)];
+static mbstate_t mb_wcin;
+#endif
+
+#ifndef _LIBCPP_HAS_NO_STDOUT
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cout[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<char>) static char __cout[sizeof(__stdoutbuf<char>)];
+static mbstate_t mb_cout;
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcout[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcout[sizeof(__stdoutbuf<wchar_t>)];
+static mbstate_t mb_wcout;
+#endif
+
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cerr[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<char>) static char __cerr[sizeof(__stdoutbuf<char>)];
+static mbstate_t mb_cerr;
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcerr[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcerr[sizeof(__stdoutbuf<wchar_t>)];
+static mbstate_t mb_wcerr;
+
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char clog[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?clog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wclog[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wclog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+
+_LIBCPP_HIDDEN ios_base::Init __start_std_streams;
+
+// On Windows the TLS storage for locales needs to be initialized before we create
+// the standard streams, otherwise it may not be alive during program termination
+// when we flush the streams.
+static void force_locale_initialization() {
+#if defined(_LIBCPP_MSVCRT_LIKE)
+  static bool once = []() {
+    auto loc = newlocale(LC_ALL_MASK, "C", 0);
+    {
+        __libcpp_locale_guard g(loc); // forces initialization of locale TLS
+        ((void)g);
+    }
+    freelocale(loc);
+    return true;
+  }();
+  ((void)once);
+#endif
+}
+
+class DoIOSInit {
+public:
+	DoIOSInit();
+	~DoIOSInit();
+};
+
+DoIOSInit::DoIOSInit()
+{
+    force_locale_initialization();
+
+#ifndef _LIBCPP_HAS_NO_STDIN
+    istream* cin_ptr  = ::new(cin)  istream(::new(__cin)  __stdinbuf <char>(stdin, &mb_cin));
+    wistream* wcin_ptr  = ::new(wcin)  wistream(::new(__wcin)  __stdinbuf <wchar_t>(stdin, &mb_wcin));
+#endif
+#ifndef _LIBCPP_HAS_NO_STDOUT
+    ostream* cout_ptr = ::new(cout) ostream(::new(__cout) __stdoutbuf<char>(stdout, &mb_cout));
+    wostream* wcout_ptr = ::new(wcout) wostream(::new(__wcout) __stdoutbuf<wchar_t>(stdout, &mb_wcout));
+#endif
+    ostream* cerr_ptr = ::new(cerr) ostream(::new(__cerr) __stdoutbuf<char>(stderr, &mb_cerr));
+                        ::new(clog) ostream(cerr_ptr->rdbuf());
+    wostream* wcerr_ptr = ::new(wcerr) wostream(::new(__wcerr) __stdoutbuf<wchar_t>(stderr, &mb_wcerr));
+                          ::new(wclog) wostream(wcerr_ptr->rdbuf());
+
+#if !defined(_LIBCPP_HAS_NO_STDIN) && !defined(_LIBCPP_HAS_NO_STDOUT)
+    cin_ptr->tie(cout_ptr);
+    wcin_ptr->tie(wcout_ptr);
+#endif
+    _VSTD::unitbuf(*cerr_ptr);
+    _VSTD::unitbuf(*wcerr_ptr);
+#ifndef _LIBCPP_HAS_NO_STDOUT
+    cerr_ptr->tie(cout_ptr);
+    wcerr_ptr->tie(wcout_ptr);
+#endif
+}
+
+DoIOSInit::~DoIOSInit()
+{
+#ifndef _LIBCPP_HAS_NO_STDOUT
+    ostream* cout_ptr = reinterpret_cast<ostream*>(cout);
+    wostream* wcout_ptr = reinterpret_cast<wostream*>(wcout);
+    cout_ptr->flush();
+    wcout_ptr->flush();
+#endif
+
+    ostream* clog_ptr = reinterpret_cast<ostream*>(clog);
+    wostream* wclog_ptr = reinterpret_cast<wostream*>(wclog);
+    clog_ptr->flush();
+    wclog_ptr->flush();
+}
+
+ios_base::Init::Init()
+{
+    static DoIOSInit init_the_streams; // gets initialized once
+}
+
+ios_base::Init::~Init()
+{
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/locale.cpp b/lib/libcxx/src/locale.cpp
new file mode 100644
index 0000000000..2757eaa5ac
--- /dev/null
+++ b/lib/libcxx/src/locale.cpp
@@ -0,0 +1,6154 @@
+//===------------------------- locale.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// On Solaris, we need to define something to make the C99 parts of localeconv
+// visible.
+#ifdef __sun__
+#define _LCONV_C99
+#endif
+
+#include "string"
+#include "locale"
+#include "codecvt"
+#include "vector"
+#include "algorithm"
+#include "typeinfo"
+#ifndef _LIBCPP_NO_EXCEPTIONS
+#  include "type_traits"
+#endif
+#include "clocale"
+#include "cstring"
+#if defined(_LIBCPP_MSVCRT)
+#define _CTYPE_DISABLE_MACROS
+#endif
+#include "cwctype"
+#include "__sso_allocator"
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+#include "support/win32/locale_win32.h"
+#elif !defined(__BIONIC__)
+#include <langinfo.h>
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include "include/atomic_support.h"
+#include "__undef_macros"
+
+// On Linux, wint_t and wchar_t have different signed-ness, and this causes
+// lots of noise in the build log, but no bugs that I know of.
+#if defined(__clang__)
+#pragma clang diagnostic ignored "-Wsign-conversion"
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct __libcpp_unique_locale {
+  __libcpp_unique_locale(const char* nm) : __loc_(newlocale(LC_ALL_MASK, nm, 0)) {}
+
+  ~__libcpp_unique_locale() {
+    if (__loc_)
+      freelocale(__loc_);
+  }
+
+  explicit operator bool() const { return __loc_; }
+
+  locale_t& get() { return __loc_; }
+
+  locale_t __loc_;
+private:
+  __libcpp_unique_locale(__libcpp_unique_locale const&);
+  __libcpp_unique_locale& operator=(__libcpp_unique_locale const&);
+};
+
+#ifdef __cloc_defined
+locale_t __cloc() {
+  // In theory this could create a race condition. In practice
+  // the race condition is non-fatal since it will just create
+  // a little resource leak. Better approach would be appreciated.
+  static locale_t result = newlocale(LC_ALL_MASK, "C", 0);
+  return result;
+}
+#endif // __cloc_defined
+
+namespace {
+
+struct release
+{
+    void operator()(locale::facet* p) {p->__release_shared();}
+};
+
+template <class T, class A0>
+inline
+T&
+make(A0 a0)
+{
+    static typename aligned_storage<sizeof(T)>::type buf;
+    auto *obj = ::new (&buf) T(a0);
+    return *obj;
+}
+
+template <class T, class A0, class A1>
+inline
+T&
+make(A0 a0, A1 a1)
+{
+    static typename aligned_storage<sizeof(T)>::type buf;
+    ::new (&buf) T(a0, a1);
+    return *reinterpret_cast<T*>(&buf);
+}
+
+template <class T, class A0, class A1, class A2>
+inline
+T&
+make(A0 a0, A1 a1, A2 a2)
+{
+    static typename aligned_storage<sizeof(T)>::type buf;
+    auto *obj = ::new (&buf) T(a0, a1, a2);
+    return *obj;
+}
+
+template <typename T, size_t N>
+inline
+_LIBCPP_CONSTEXPR
+size_t
+countof(const T (&)[N])
+{
+    return N;
+}
+
+template <typename T>
+inline
+_LIBCPP_CONSTEXPR
+size_t
+countof(const T * const begin, const T * const end)
+{
+    return static_cast<size_t>(end - begin);
+}
+
+_LIBCPP_NORETURN static void __throw_runtime_error(const string &msg)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw runtime_error(msg);
+#else
+    (void)msg;
+    _VSTD::abort();
+#endif
+}
+
+}
+
+#if defined(_AIX)
+// Set priority to INT_MIN + 256 + 150
+# pragma priority ( -2147483242 )
+#endif
+
+const locale::category locale::none;
+const locale::category locale::collate;
+const locale::category locale::ctype;
+const locale::category locale::monetary;
+const locale::category locale::numeric;
+const locale::category locale::time;
+const locale::category locale::messages;
+const locale::category locale::all;
+
+class _LIBCPP_HIDDEN locale::__imp
+    : public facet
+{
+    enum {N = 28};
+#if defined(_LIBCPP_COMPILER_MSVC)
+// FIXME: MSVC doesn't support aligned parameters by value.
+// I can't get the __sso_allocator to work here
+// for MSVC I think for this reason.
+    vector<facet*> facets_;
+#else
+    vector<facet*, __sso_allocator<facet*, N> > facets_;
+#endif
+    string         name_;
+public:
+    explicit __imp(size_t refs = 0);
+    explicit __imp(const string& name, size_t refs = 0);
+    __imp(const __imp&);
+    __imp(const __imp&, const string&, locale::category c);
+    __imp(const __imp& other, const __imp& one, locale::category c);
+    __imp(const __imp&, facet* f, long id);
+    ~__imp();
+
+    const string& name() const {return name_;}
+    bool has_facet(long id) const
+        {return static_cast<size_t>(id) < facets_.size() && facets_[static_cast<size_t>(id)];}
+    const locale::facet* use_facet(long id) const;
+
+    static const locale& make_classic();
+    static       locale& make_global();
+private:
+    void install(facet* f, long id);
+    template <class F> void install(F* f) {install(f, f->id.__get());}
+    template <class F> void install_from(const __imp& other);
+};
+
+locale::__imp::__imp(size_t refs)
+    : facet(refs),
+      facets_(N),
+      name_("C")
+{
+    facets_.clear();
+    install(&make<_VSTD::collate<char> >(1u));
+    install(&make<_VSTD::collate<wchar_t> >(1u));
+    install(&make<_VSTD::ctype<char> >(nullptr, false, 1u));
+    install(&make<_VSTD::ctype<wchar_t> >(1u));
+    install(&make<codecvt<char, char, mbstate_t> >(1u));
+    install(&make<codecvt<wchar_t, char, mbstate_t> >(1u));
+    install(&make<codecvt<char16_t, char, mbstate_t> >(1u));
+    install(&make<codecvt<char32_t, char, mbstate_t> >(1u));
+    install(&make<numpunct<char> >(1u));
+    install(&make<numpunct<wchar_t> >(1u));
+    install(&make<num_get<char> >(1u));
+    install(&make<num_get<wchar_t> >(1u));
+    install(&make<num_put<char> >(1u));
+    install(&make<num_put<wchar_t> >(1u));
+    install(&make<moneypunct<char, false> >(1u));
+    install(&make<moneypunct<char, true> >(1u));
+    install(&make<moneypunct<wchar_t, false> >(1u));
+    install(&make<moneypunct<wchar_t, true> >(1u));
+    install(&make<money_get<char> >(1u));
+    install(&make<money_get<wchar_t> >(1u));
+    install(&make<money_put<char> >(1u));
+    install(&make<money_put<wchar_t> >(1u));
+    install(&make<time_get<char> >(1u));
+    install(&make<time_get<wchar_t> >(1u));
+    install(&make<time_put<char> >(1u));
+    install(&make<time_put<wchar_t> >(1u));
+    install(&make<_VSTD::messages<char> >(1u));
+    install(&make<_VSTD::messages<wchar_t> >(1u));
+}
+
+locale::__imp::__imp(const string& name, size_t refs)
+    : facet(refs),
+      facets_(N),
+      name_(name)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        facets_ = locale::classic().__locale_->facets_;
+        for (unsigned i = 0; i < facets_.size(); ++i)
+            if (facets_[i])
+                facets_[i]->__add_shared();
+        install(new collate_byname<char>(name_));
+        install(new collate_byname<wchar_t>(name_));
+        install(new ctype_byname<char>(name_));
+        install(new ctype_byname<wchar_t>(name_));
+        install(new codecvt_byname<char, char, mbstate_t>(name_));
+        install(new codecvt_byname<wchar_t, char, mbstate_t>(name_));
+        install(new codecvt_byname<char16_t, char, mbstate_t>(name_));
+        install(new codecvt_byname<char32_t, char, mbstate_t>(name_));
+        install(new numpunct_byname<char>(name_));
+        install(new numpunct_byname<wchar_t>(name_));
+        install(new moneypunct_byname<char, false>(name_));
+        install(new moneypunct_byname<char, true>(name_));
+        install(new moneypunct_byname<wchar_t, false>(name_));
+        install(new moneypunct_byname<wchar_t, true>(name_));
+        install(new time_get_byname<char>(name_));
+        install(new time_get_byname<wchar_t>(name_));
+        install(new time_put_byname<char>(name_));
+        install(new time_put_byname<wchar_t>(name_));
+        install(new messages_byname<char>(name_));
+        install(new messages_byname<wchar_t>(name_));
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (unsigned i = 0; i < facets_.size(); ++i)
+            if (facets_[i])
+                facets_[i]->__release_shared();
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+// NOTE avoid the `base class should be explicitly initialized in the
+// copy constructor` warning emitted by GCC
+#if defined(__clang__) || _GNUC_VER >= 406
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wextra"
+#endif
+
+locale::__imp::__imp(const __imp& other)
+    : facets_(max<size_t>(N, other.facets_.size())),
+      name_(other.name_)
+{
+    facets_ = other.facets_;
+    for (unsigned i = 0; i < facets_.size(); ++i)
+        if (facets_[i])
+            facets_[i]->__add_shared();
+}
+
+#if defined(__clang__) || _GNUC_VER >= 406
+#pragma GCC diagnostic pop
+#endif
+
+locale::__imp::__imp(const __imp& other, const string& name, locale::category c)
+    : facets_(N),
+      name_("*")
+{
+    facets_ = other.facets_;
+    for (unsigned i = 0; i < facets_.size(); ++i)
+        if (facets_[i])
+            facets_[i]->__add_shared();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        if (c & locale::collate)
+        {
+            install(new collate_byname<char>(name));
+            install(new collate_byname<wchar_t>(name));
+        }
+        if (c & locale::ctype)
+        {
+            install(new ctype_byname<char>(name));
+            install(new ctype_byname<wchar_t>(name));
+            install(new codecvt_byname<char, char, mbstate_t>(name));
+            install(new codecvt_byname<wchar_t, char, mbstate_t>(name));
+            install(new codecvt_byname<char16_t, char, mbstate_t>(name));
+            install(new codecvt_byname<char32_t, char, mbstate_t>(name));
+        }
+        if (c & locale::monetary)
+        {
+            install(new moneypunct_byname<char, false>(name));
+            install(new moneypunct_byname<char, true>(name));
+            install(new moneypunct_byname<wchar_t, false>(name));
+            install(new moneypunct_byname<wchar_t, true>(name));
+        }
+        if (c & locale::numeric)
+        {
+            install(new numpunct_byname<char>(name));
+            install(new numpunct_byname<wchar_t>(name));
+        }
+        if (c & locale::time)
+        {
+            install(new time_get_byname<char>(name));
+            install(new time_get_byname<wchar_t>(name));
+            install(new time_put_byname<char>(name));
+            install(new time_put_byname<wchar_t>(name));
+        }
+        if (c & locale::messages)
+        {
+            install(new messages_byname<char>(name));
+            install(new messages_byname<wchar_t>(name));
+        }
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (unsigned i = 0; i < facets_.size(); ++i)
+            if (facets_[i])
+                facets_[i]->__release_shared();
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class F>
+inline
+void
+locale::__imp::install_from(const locale::__imp& one)
+{
+    long id = F::id.__get();
+    install(const_cast<F*>(static_cast<const F*>(one.use_facet(id))), id);
+}
+
+locale::__imp::__imp(const __imp& other, const __imp& one, locale::category c)
+    : facets_(N),
+      name_("*")
+{
+    facets_ = other.facets_;
+    for (unsigned i = 0; i < facets_.size(); ++i)
+        if (facets_[i])
+            facets_[i]->__add_shared();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        if (c & locale::collate)
+        {
+            install_from<_VSTD::collate<char> >(one);
+            install_from<_VSTD::collate<wchar_t> >(one);
+        }
+        if (c & locale::ctype)
+        {
+            install_from<_VSTD::ctype<char> >(one);
+            install_from<_VSTD::ctype<wchar_t> >(one);
+            install_from<_VSTD::codecvt<char, char, mbstate_t> >(one);
+            install_from<_VSTD::codecvt<char16_t, char, mbstate_t> >(one);
+            install_from<_VSTD::codecvt<char32_t, char, mbstate_t> >(one);
+            install_from<_VSTD::codecvt<wchar_t, char, mbstate_t> >(one);
+        }
+        if (c & locale::monetary)
+        {
+            install_from<moneypunct<char, false> >(one);
+            install_from<moneypunct<char, true> >(one);
+            install_from<moneypunct<wchar_t, false> >(one);
+            install_from<moneypunct<wchar_t, true> >(one);
+            install_from<money_get<char> >(one);
+            install_from<money_get<wchar_t> >(one);
+            install_from<money_put<char> >(one);
+            install_from<money_put<wchar_t> >(one);
+        }
+        if (c & locale::numeric)
+        {
+            install_from<numpunct<char> >(one);
+            install_from<numpunct<wchar_t> >(one);
+            install_from<num_get<char> >(one);
+            install_from<num_get<wchar_t> >(one);
+            install_from<num_put<char> >(one);
+            install_from<num_put<wchar_t> >(one);
+        }
+        if (c & locale::time)
+        {
+            install_from<time_get<char> >(one);
+            install_from<time_get<wchar_t> >(one);
+            install_from<time_put<char> >(one);
+            install_from<time_put<wchar_t> >(one);
+        }
+        if (c & locale::messages)
+        {
+            install_from<_VSTD::messages<char> >(one);
+            install_from<_VSTD::messages<wchar_t> >(one);
+        }
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (unsigned i = 0; i < facets_.size(); ++i)
+            if (facets_[i])
+                facets_[i]->__release_shared();
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+locale::__imp::__imp(const __imp& other, facet* f, long id)
+    : facets_(max<size_t>(N, other.facets_.size()+1)),
+      name_("*")
+{
+    f->__add_shared();
+    unique_ptr<facet, release> hold(f);
+    facets_ = other.facets_;
+    for (unsigned i = 0; i < other.facets_.size(); ++i)
+        if (facets_[i])
+            facets_[i]->__add_shared();
+    install(hold.get(), id);
+}
+
+locale::__imp::~__imp()
+{
+    for (unsigned i = 0; i < facets_.size(); ++i)
+        if (facets_[i])
+            facets_[i]->__release_shared();
+}
+
+void
+locale::__imp::install(facet* f, long id)
+{
+    f->__add_shared();
+    unique_ptr<facet, release> hold(f);
+    if (static_cast<size_t>(id) >= facets_.size())
+        facets_.resize(static_cast<size_t>(id+1));
+    if (facets_[static_cast<size_t>(id)])
+        facets_[static_cast<size_t>(id)]->__release_shared();
+    facets_[static_cast<size_t>(id)] = hold.release();
+}
+
+const locale::facet*
+locale::__imp::use_facet(long id) const
+{
+    if (!has_facet(id))
+        __throw_bad_cast();
+    return facets_[static_cast<size_t>(id)];
+}
+
+// locale
+
+const locale&
+locale::__imp::make_classic()
+{
+    // only one thread can get in here and it only gets in once
+    static aligned_storage<sizeof(locale)>::type buf;
+    locale* c = reinterpret_cast<locale*>(&buf);
+    c->__locale_ = &make<__imp>(1u);
+    return *c;
+}
+
+const locale&
+locale::classic()
+{
+    static const locale& c = __imp::make_classic();
+    return c;
+}
+
+locale&
+locale::__imp::make_global()
+{
+    // only one thread can get in here and it only gets in once
+    static aligned_storage<sizeof(locale)>::type buf;
+    auto *obj = ::new (&buf) locale(locale::classic());
+    return *obj;
+}
+
+locale&
+locale::__global()
+{
+    static locale& g = __imp::make_global();
+    return g;
+}
+
+locale::locale()  _NOEXCEPT
+    : __locale_(__global().__locale_)
+{
+    __locale_->__add_shared();
+}
+
+locale::locale(const locale& l)  _NOEXCEPT
+    : __locale_(l.__locale_)
+{
+    __locale_->__add_shared();
+}
+
+locale::~locale()
+{
+    __locale_->__release_shared();
+}
+
+const locale&
+locale::operator=(const locale& other)  _NOEXCEPT
+{
+    other.__locale_->__add_shared();
+    __locale_->__release_shared();
+    __locale_ = other.__locale_;
+    return *this;
+}
+
+locale::locale(const char* name)
+    : __locale_(name ? new __imp(name)
+                     : (__throw_runtime_error("locale constructed with null"), (__imp*)0))
+{
+    __locale_->__add_shared();
+}
+
+locale::locale(const string& name)
+    : __locale_(new __imp(name))
+{
+    __locale_->__add_shared();
+}
+
+locale::locale(const locale& other, const char* name, category c)
+    : __locale_(name ? new __imp(*other.__locale_, name, c)
+                     : (__throw_runtime_error("locale constructed with null"), (__imp*)0))
+{
+    __locale_->__add_shared();
+}
+
+locale::locale(const locale& other, const string& name, category c)
+    : __locale_(new __imp(*other.__locale_, name, c))
+{
+    __locale_->__add_shared();
+}
+
+locale::locale(const locale& other, const locale& one, category c)
+    : __locale_(new __imp(*other.__locale_, *one.__locale_, c))
+{
+    __locale_->__add_shared();
+}
+
+string
+locale::name() const
+{
+    return __locale_->name();
+}
+
+void
+locale::__install_ctor(const locale& other, facet* f, long id)
+{
+    if (f)
+        __locale_ = new __imp(*other.__locale_, f, id);
+    else
+        __locale_ = other.__locale_;
+    __locale_->__add_shared();
+}
+
+locale
+locale::global(const locale& loc)
+{
+    locale& g = __global();
+    locale r = g;
+    g = loc;
+    if (g.name() != "*")
+        setlocale(LC_ALL, g.name().c_str());
+    return r;
+}
+
+bool
+locale::has_facet(id& x) const
+{
+    return __locale_->has_facet(x.__get());
+}
+
+const locale::facet*
+locale::use_facet(id& x) const
+{
+    return __locale_->use_facet(x.__get());
+}
+
+bool
+locale::operator==(const locale& y) const
+{
+    return (__locale_ == y.__locale_)
+        || (__locale_->name() != "*" && __locale_->name() == y.__locale_->name());
+}
+
+// locale::facet
+
+locale::facet::~facet()
+{
+}
+
+void
+locale::facet::__on_zero_shared() _NOEXCEPT
+{
+    delete this;
+}
+
+// locale::id
+
+int32_t locale::id::__next_id = 0;
+
+namespace
+{
+
+class __fake_bind
+{
+    locale::id* id_;
+    void (locale::id::* pmf_)();
+public:
+    __fake_bind(void (locale::id::* pmf)(), locale::id* id)
+        : id_(id), pmf_(pmf) {}
+
+    void operator()() const
+    {
+        (id_->*pmf_)();
+    }
+};
+
+}
+
+long
+locale::id::__get()
+{
+    call_once(__flag_, __fake_bind(&locale::id::__init, this));
+    return __id_ - 1;
+}
+
+void
+locale::id::__init()
+{
+    __id_ = __libcpp_atomic_add(&__next_id, 1);
+}
+
+// template <> class collate_byname<char>
+
+collate_byname<char>::collate_byname(const char* n, size_t refs)
+    : collate<char>(refs),
+      __l(newlocale(LC_ALL_MASK, n, 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("collate_byname<char>::collate_byname"
+                            " failed to construct for " + string(n));
+}
+
+collate_byname<char>::collate_byname(const string& name, size_t refs)
+    : collate<char>(refs),
+      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("collate_byname<char>::collate_byname"
+                            " failed to construct for " + name);
+}
+
+collate_byname<char>::~collate_byname()
+{
+    freelocale(__l);
+}
+
+int
+collate_byname<char>::do_compare(const char_type* __lo1, const char_type* __hi1,
+                                 const char_type* __lo2, const char_type* __hi2) const
+{
+    string_type lhs(__lo1, __hi1);
+    string_type rhs(__lo2, __hi2);
+    int r = strcoll_l(lhs.c_str(), rhs.c_str(), __l);
+    if (r < 0)
+        return -1;
+    if (r > 0)
+        return 1;
+    return r;
+}
+
+collate_byname<char>::string_type
+collate_byname<char>::do_transform(const char_type* lo, const char_type* hi) const
+{
+    const string_type in(lo, hi);
+    string_type out(strxfrm_l(0, in.c_str(), 0, __l), char());
+    strxfrm_l(const_cast<char*>(out.c_str()), in.c_str(), out.size()+1, __l);
+    return out;
+}
+
+// template <> class collate_byname<wchar_t>
+
+collate_byname<wchar_t>::collate_byname(const char* n, size_t refs)
+    : collate<wchar_t>(refs),
+      __l(newlocale(LC_ALL_MASK, n, 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("collate_byname<wchar_t>::collate_byname(size_t refs)"
+                            " failed to construct for " + string(n));
+}
+
+collate_byname<wchar_t>::collate_byname(const string& name, size_t refs)
+    : collate<wchar_t>(refs),
+      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("collate_byname<wchar_t>::collate_byname(size_t refs)"
+                            " failed to construct for " + name);
+}
+
+collate_byname<wchar_t>::~collate_byname()
+{
+    freelocale(__l);
+}
+
+int
+collate_byname<wchar_t>::do_compare(const char_type* __lo1, const char_type* __hi1,
+                                 const char_type* __lo2, const char_type* __hi2) const
+{
+    string_type lhs(__lo1, __hi1);
+    string_type rhs(__lo2, __hi2);
+    int r = wcscoll_l(lhs.c_str(), rhs.c_str(), __l);
+    if (r < 0)
+        return -1;
+    if (r > 0)
+        return 1;
+    return r;
+}
+
+collate_byname<wchar_t>::string_type
+collate_byname<wchar_t>::do_transform(const char_type* lo, const char_type* hi) const
+{
+    const string_type in(lo, hi);
+    string_type out(wcsxfrm_l(0, in.c_str(), 0, __l), wchar_t());
+    wcsxfrm_l(const_cast<wchar_t*>(out.c_str()), in.c_str(), out.size()+1, __l);
+    return out;
+}
+
+// template <> class ctype<wchar_t>;
+
+const ctype_base::mask ctype_base::space;
+const ctype_base::mask ctype_base::print;
+const ctype_base::mask ctype_base::cntrl;
+const ctype_base::mask ctype_base::upper;
+const ctype_base::mask ctype_base::lower;
+const ctype_base::mask ctype_base::alpha;
+const ctype_base::mask ctype_base::digit;
+const ctype_base::mask ctype_base::punct;
+const ctype_base::mask ctype_base::xdigit;
+const ctype_base::mask ctype_base::blank;
+const ctype_base::mask ctype_base::alnum;
+const ctype_base::mask ctype_base::graph;
+
+locale::id ctype<wchar_t>::id;
+
+ctype<wchar_t>::~ctype()
+{
+}
+
+bool
+ctype<wchar_t>::do_is(mask m, char_type c) const
+{
+    return isascii(c) ? (ctype<char>::classic_table()[c] & m) != 0 : false;
+}
+
+const wchar_t*
+ctype<wchar_t>::do_is(const char_type* low, const char_type* high, mask* vec) const
+{
+    for (; low != high; ++low, ++vec)
+        *vec = static_cast<mask>(isascii(*low) ?
+                                   ctype<char>::classic_table()[*low] : 0);
+    return low;
+}
+
+const wchar_t*
+ctype<wchar_t>::do_scan_is(mask m, const char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        if (isascii(*low) && (ctype<char>::classic_table()[*low] & m))
+            break;
+    return low;
+}
+
+const wchar_t*
+ctype<wchar_t>::do_scan_not(mask m, const char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        if (!(isascii(*low) && (ctype<char>::classic_table()[*low] & m)))
+            break;
+    return low;
+}
+
+wchar_t
+ctype<wchar_t>::do_toupper(char_type c) const
+{
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+    return isascii(c) ? _DefaultRuneLocale.__mapupper[c] : c;
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__)
+    return isascii(c) ? ctype<char>::__classic_upper_table()[c] : c;
+#else
+    return (isascii(c) && iswlower_l(c, _LIBCPP_GET_C_LOCALE)) ? c-L'a'+L'A' : c;
+#endif
+}
+
+const wchar_t*
+ctype<wchar_t>::do_toupper(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+        *low = isascii(*low) ? _DefaultRuneLocale.__mapupper[*low] : *low;
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__)
+        *low = isascii(*low) ? ctype<char>::__classic_upper_table()[*low]
+                             : *low;
+#else
+        *low = (isascii(*low) && islower_l(*low, _LIBCPP_GET_C_LOCALE)) ? (*low-L'a'+L'A') : *low;
+#endif
+    return low;
+}
+
+wchar_t
+ctype<wchar_t>::do_tolower(char_type c) const
+{
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+    return isascii(c) ? _DefaultRuneLocale.__maplower[c] : c;
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__)
+    return isascii(c) ? ctype<char>::__classic_lower_table()[c] : c;
+#else
+    return (isascii(c) && isupper_l(c, _LIBCPP_GET_C_LOCALE)) ? c-L'A'+'a' : c;
+#endif
+}
+
+const wchar_t*
+ctype<wchar_t>::do_tolower(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+        *low = isascii(*low) ? _DefaultRuneLocale.__maplower[*low] : *low;
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__) || \
+      defined(__NetBSD__)
+        *low = isascii(*low) ? ctype<char>::__classic_lower_table()[*low]
+                             : *low;
+#else
+        *low = (isascii(*low) && isupper_l(*low, _LIBCPP_GET_C_LOCALE)) ? *low-L'A'+L'a' : *low;
+#endif
+    return low;
+}
+
+wchar_t
+ctype<wchar_t>::do_widen(char c) const
+{
+    return c;
+}
+
+const char*
+ctype<wchar_t>::do_widen(const char* low, const char* high, char_type* dest) const
+{
+    for (; low != high; ++low, ++dest)
+        *dest = *low;
+    return low;
+}
+
+char
+ctype<wchar_t>::do_narrow(char_type c, char dfault) const
+{
+    if (isascii(c))
+        return static_cast<char>(c);
+    return dfault;
+}
+
+const wchar_t*
+ctype<wchar_t>::do_narrow(const char_type* low, const char_type* high, char dfault, char* dest) const
+{
+    for (; low != high; ++low, ++dest)
+        if (isascii(*low))
+            *dest = static_cast<char>(*low);
+        else
+            *dest = dfault;
+    return low;
+}
+
+// template <> class ctype<char>;
+
+locale::id ctype<char>::id;
+
+ctype<char>::ctype(const mask* tab, bool del, size_t refs)
+    : locale::facet(refs),
+      __tab_(tab),
+      __del_(del)
+{
+  if (__tab_ == 0)
+      __tab_ = classic_table();
+}
+
+ctype<char>::~ctype()
+{
+    if (__tab_ && __del_)
+        delete [] __tab_;
+}
+
+char
+ctype<char>::do_toupper(char_type c) const
+{
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+    return isascii(c) ?
+      static_cast<char>(_DefaultRuneLocale.__mapupper[static_cast<ptrdiff_t>(c)]) : c;
+#elif defined(__NetBSD__)
+    return static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(c)]);
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+    return isascii(c) ?
+      static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(c)]) : c;
+#else
+    return (isascii(c) && islower_l(c, _LIBCPP_GET_C_LOCALE)) ? c-'a'+'A' : c;
+#endif
+}
+
+const char*
+ctype<char>::do_toupper(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+        *low = isascii(*low) ?
+          static_cast<char>(_DefaultRuneLocale.__mapupper[static_cast<ptrdiff_t>(*low)]) : *low;
+#elif defined(__NetBSD__)
+        *low = static_cast<char>(__classic_upper_table()[static_cast<unsigned char>(*low)]);
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+        *low = isascii(*low) ?
+          static_cast<char>(__classic_upper_table()[static_cast<size_t>(*low)]) : *low;
+#else
+        *low = (isascii(*low) && islower_l(*low, _LIBCPP_GET_C_LOCALE)) ? *low-'a'+'A' : *low;
+#endif
+    return low;
+}
+
+char
+ctype<char>::do_tolower(char_type c) const
+{
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+    return isascii(c) ?
+      static_cast<char>(_DefaultRuneLocale.__maplower[static_cast<ptrdiff_t>(c)]) : c;
+#elif defined(__NetBSD__)
+    return static_cast<char>(__classic_lower_table()[static_cast<unsigned char>(c)]);
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+    return isascii(c) ?
+      static_cast<char>(__classic_lower_table()[static_cast<size_t>(c)]) : c;
+#else
+    return (isascii(c) && isupper_l(c, _LIBCPP_GET_C_LOCALE)) ? c-'A'+'a' : c;
+#endif
+}
+
+const char*
+ctype<char>::do_tolower(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+#ifdef _LIBCPP_HAS_DEFAULTRUNELOCALE
+        *low = isascii(*low) ? static_cast<char>(_DefaultRuneLocale.__maplower[static_cast<ptrdiff_t>(*low)]) : *low;
+#elif defined(__NetBSD__)
+        *low = static_cast<char>(__classic_lower_table()[static_cast<unsigned char>(*low)]);
+#elif defined(__GLIBC__) || defined(__EMSCRIPTEN__)
+        *low = isascii(*low) ? static_cast<char>(__classic_lower_table()[static_cast<size_t>(*low)]) : *low;
+#else
+        *low = (isascii(*low) && isupper_l(*low, _LIBCPP_GET_C_LOCALE)) ? *low-'A'+'a' : *low;
+#endif
+    return low;
+}
+
+char
+ctype<char>::do_widen(char c) const
+{
+    return c;
+}
+
+const char*
+ctype<char>::do_widen(const char* low, const char* high, char_type* dest) const
+{
+    for (; low != high; ++low, ++dest)
+        *dest = *low;
+    return low;
+}
+
+char
+ctype<char>::do_narrow(char_type c, char dfault) const
+{
+    if (isascii(c))
+        return static_cast<char>(c);
+    return dfault;
+}
+
+const char*
+ctype<char>::do_narrow(const char_type* low, const char_type* high, char dfault, char* dest) const
+{
+    for (; low != high; ++low, ++dest)
+        if (isascii(*low))
+            *dest = *low;
+        else
+            *dest = dfault;
+    return low;
+}
+
+#if defined(__EMSCRIPTEN__)
+extern "C" const unsigned short ** __ctype_b_loc();
+extern "C" const int ** __ctype_tolower_loc();
+extern "C" const int ** __ctype_toupper_loc();
+#endif
+
+#ifdef _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
+const ctype<char>::mask*
+ctype<char>::classic_table()  _NOEXCEPT
+{
+    static _LIBCPP_CONSTEXPR const ctype<char>::mask builtin_table[table_size] = {
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl | space | blank,
+        cntrl | space,                  cntrl | space,
+        cntrl | space,                  cntrl | space,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        cntrl,                          cntrl,
+        space | blank | print,          punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        digit | print | xdigit,         digit | print | xdigit,
+        digit | print | xdigit,         digit | print | xdigit,
+        digit | print | xdigit,         digit | print | xdigit,
+        digit | print | xdigit,         digit | print | xdigit,
+        digit | print | xdigit,         digit | print | xdigit,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  upper | xdigit | print | alpha,
+        upper | xdigit | print | alpha, upper | xdigit | print | alpha,
+        upper | xdigit | print | alpha, upper | xdigit | print | alpha,
+        upper | xdigit | print | alpha, upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          upper | print | alpha,
+        upper | print | alpha,          punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  lower | xdigit | print | alpha,
+        lower | xdigit | print | alpha, lower | xdigit | print | alpha,
+        lower | xdigit | print | alpha, lower | xdigit | print | alpha,
+        lower | xdigit | print | alpha, lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          lower | print | alpha,
+        lower | print | alpha,          punct | print,
+        punct | print,                  punct | print,
+        punct | print,                  cntrl,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    };
+    return builtin_table;
+}
+#else
+const ctype<char>::mask*
+ctype<char>::classic_table()  _NOEXCEPT
+{
+#if defined(__APPLE__) || defined(__FreeBSD__)
+    return _DefaultRuneLocale.__runetype;
+#elif defined(__NetBSD__)
+    return _C_ctype_tab_ + 1;
+#elif defined(__GLIBC__)
+    return _LIBCPP_GET_C_LOCALE->__ctype_b;
+#elif __sun__
+    return __ctype_mask;
+#elif defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    return __pctype_func();
+#elif defined(__EMSCRIPTEN__)
+    return *__ctype_b_loc();
+#elif defined(_NEWLIB_VERSION)
+    // Newlib has a 257-entry table in ctype_.c, where (char)0 starts at [1].
+    return _ctype_ + 1;
+#elif defined(_AIX)
+    return (const unsigned int *)__lc_ctype_ptr->obj->mask;
+#else
+    // Platform not supported: abort so the person doing the port knows what to
+    // fix
+# warning  ctype<char>::classic_table() is not implemented
+    printf("ctype<char>::classic_table() is not implemented\n");
+    abort();
+    return NULL;
+#endif
+}
+#endif
+
+#if defined(__GLIBC__)
+const int*
+ctype<char>::__classic_lower_table() _NOEXCEPT
+{
+    return _LIBCPP_GET_C_LOCALE->__ctype_tolower;
+}
+
+const int*
+ctype<char>::__classic_upper_table() _NOEXCEPT
+{
+    return _LIBCPP_GET_C_LOCALE->__ctype_toupper;
+}
+#elif __NetBSD__
+const short*
+ctype<char>::__classic_lower_table() _NOEXCEPT
+{
+    return _C_tolower_tab_ + 1;
+}
+
+const short*
+ctype<char>::__classic_upper_table() _NOEXCEPT
+{
+    return _C_toupper_tab_ + 1;
+}
+
+#elif defined(__EMSCRIPTEN__)
+const int*
+ctype<char>::__classic_lower_table() _NOEXCEPT
+{
+    return *__ctype_tolower_loc();
+}
+
+const int*
+ctype<char>::__classic_upper_table() _NOEXCEPT
+{
+    return *__ctype_toupper_loc();
+}
+#endif // __GLIBC__ || __NETBSD__ || __EMSCRIPTEN__
+
+// template <> class ctype_byname<char>
+
+ctype_byname<char>::ctype_byname(const char* name, size_t refs)
+    : ctype<char>(0, false, refs),
+      __l(newlocale(LC_ALL_MASK, name, 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("ctype_byname<char>::ctype_byname"
+                            " failed to construct for " + string(name));
+}
+
+ctype_byname<char>::ctype_byname(const string& name, size_t refs)
+    : ctype<char>(0, false, refs),
+      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("ctype_byname<char>::ctype_byname"
+                            " failed to construct for " + name);
+}
+
+ctype_byname<char>::~ctype_byname()
+{
+    freelocale(__l);
+}
+
+char
+ctype_byname<char>::do_toupper(char_type c) const
+{
+    return static_cast<char>(toupper_l(static_cast<unsigned char>(c), __l));
+}
+
+const char*
+ctype_byname<char>::do_toupper(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        *low = static_cast<char>(toupper_l(static_cast<unsigned char>(*low), __l));
+    return low;
+}
+
+char
+ctype_byname<char>::do_tolower(char_type c) const
+{
+    return static_cast<char>(tolower_l(static_cast<unsigned char>(c), __l));
+}
+
+const char*
+ctype_byname<char>::do_tolower(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        *low = static_cast<char>(tolower_l(static_cast<unsigned char>(*low), __l));
+    return low;
+}
+
+// template <> class ctype_byname<wchar_t>
+
+ctype_byname<wchar_t>::ctype_byname(const char* name, size_t refs)
+    : ctype<wchar_t>(refs),
+      __l(newlocale(LC_ALL_MASK, name, 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("ctype_byname<wchar_t>::ctype_byname"
+                            " failed to construct for " + string(name));
+}
+
+ctype_byname<wchar_t>::ctype_byname(const string& name, size_t refs)
+    : ctype<wchar_t>(refs),
+      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("ctype_byname<wchar_t>::ctype_byname"
+                            " failed to construct for " + name);
+}
+
+ctype_byname<wchar_t>::~ctype_byname()
+{
+    freelocale(__l);
+}
+
+bool
+ctype_byname<wchar_t>::do_is(mask m, char_type c) const
+{
+#ifdef _LIBCPP_WCTYPE_IS_MASK
+    return static_cast<bool>(iswctype_l(c, m, __l));
+#else
+    bool result = false;
+    wint_t ch = static_cast<wint_t>(c);
+    if ((m & space) == space) result |= (iswspace_l(ch, __l) != 0);
+    if ((m & print) == print) result |= (iswprint_l(ch, __l) != 0);
+    if ((m & cntrl) == cntrl) result |= (iswcntrl_l(ch, __l) != 0);
+    if ((m & upper) == upper) result |= (iswupper_l(ch, __l) != 0);
+    if ((m & lower) == lower) result |= (iswlower_l(ch, __l) != 0);
+    if ((m & alpha) == alpha) result |= (iswalpha_l(ch, __l) != 0);
+    if ((m & digit) == digit) result |= (iswdigit_l(ch, __l) != 0);
+    if ((m & punct) == punct) result |= (iswpunct_l(ch, __l) != 0);
+    if ((m & xdigit) == xdigit) result |= (iswxdigit_l(ch, __l) != 0);
+    if ((m & blank) == blank) result |= (iswblank_l(ch, __l) != 0);
+    return result;
+#endif
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_is(const char_type* low, const char_type* high, mask* vec) const
+{
+    for (; low != high; ++low, ++vec)
+    {
+        if (isascii(*low))
+            *vec = static_cast<mask>(ctype<char>::classic_table()[*low]);
+        else
+        {
+            *vec = 0;
+            wint_t ch = static_cast<wint_t>(*low);
+            if (iswspace_l(ch, __l))
+                *vec |= space;
+#ifndef _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
+            if (iswprint_l(ch, __l))
+                *vec |= print;
+#endif
+            if (iswcntrl_l(ch, __l))
+                *vec |= cntrl;
+            if (iswupper_l(ch, __l))
+                *vec |= upper;
+            if (iswlower_l(ch, __l))
+                *vec |= lower;
+#ifndef _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
+            if (iswalpha_l(ch, __l))
+                *vec |= alpha;
+#endif
+            if (iswdigit_l(ch, __l))
+                *vec |= digit;
+            if (iswpunct_l(ch, __l))
+                *vec |= punct;
+#ifndef _LIBCPP_CTYPE_MASK_IS_COMPOSITE_XDIGIT
+            if (iswxdigit_l(ch, __l))
+                *vec |= xdigit;
+#endif
+#if !defined(__sun__)
+            if (iswblank_l(ch, __l))
+                *vec |= blank;
+#endif
+        }
+    }
+    return low;
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_scan_is(mask m, const char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+    {
+#ifdef _LIBCPP_WCTYPE_IS_MASK
+        if (iswctype_l(*low, m, __l))
+            break;
+#else
+        wint_t ch = static_cast<wint_t>(*low);
+        if ((m & space) == space && iswspace_l(ch, __l)) break;
+        if ((m & print) == print && iswprint_l(ch, __l)) break;
+        if ((m & cntrl) == cntrl && iswcntrl_l(ch, __l)) break;
+        if ((m & upper) == upper && iswupper_l(ch, __l)) break;
+        if ((m & lower) == lower && iswlower_l(ch, __l)) break;
+        if ((m & alpha) == alpha && iswalpha_l(ch, __l)) break;
+        if ((m & digit) == digit && iswdigit_l(ch, __l)) break;
+        if ((m & punct) == punct && iswpunct_l(ch, __l)) break;
+        if ((m & xdigit) == xdigit && iswxdigit_l(ch, __l)) break;
+        if ((m & blank) == blank && iswblank_l(ch, __l)) break;
+#endif
+    }
+    return low;
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_scan_not(mask m, const char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+    {
+#ifdef _LIBCPP_WCTYPE_IS_MASK
+        if (!iswctype_l(*low, m, __l))
+            break;
+#else
+        wint_t ch = static_cast<wint_t>(*low);
+        if ((m & space) == space && iswspace_l(ch, __l)) continue;
+        if ((m & print) == print && iswprint_l(ch, __l)) continue;
+        if ((m & cntrl) == cntrl && iswcntrl_l(ch, __l)) continue;
+        if ((m & upper) == upper && iswupper_l(ch, __l)) continue;
+        if ((m & lower) == lower && iswlower_l(ch, __l)) continue;
+        if ((m & alpha) == alpha && iswalpha_l(ch, __l)) continue;
+        if ((m & digit) == digit && iswdigit_l(ch, __l)) continue;
+        if ((m & punct) == punct && iswpunct_l(ch, __l)) continue;
+        if ((m & xdigit) == xdigit && iswxdigit_l(ch, __l)) continue;
+        if ((m & blank) == blank && iswblank_l(ch, __l)) continue;
+        break;
+#endif
+    }
+    return low;
+}
+
+wchar_t
+ctype_byname<wchar_t>::do_toupper(char_type c) const
+{
+    return towupper_l(c, __l);
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_toupper(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        *low = towupper_l(*low, __l);
+    return low;
+}
+
+wchar_t
+ctype_byname<wchar_t>::do_tolower(char_type c) const
+{
+    return towlower_l(c, __l);
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_tolower(char_type* low, const char_type* high) const
+{
+    for (; low != high; ++low)
+        *low = towlower_l(*low, __l);
+    return low;
+}
+
+wchar_t
+ctype_byname<wchar_t>::do_widen(char c) const
+{
+    return __libcpp_btowc_l(c, __l);
+}
+
+const char*
+ctype_byname<wchar_t>::do_widen(const char* low, const char* high, char_type* dest) const
+{
+    for (; low != high; ++low, ++dest)
+        *dest = __libcpp_btowc_l(*low, __l);
+    return low;
+}
+
+char
+ctype_byname<wchar_t>::do_narrow(char_type c, char dfault) const
+{
+    int r = __libcpp_wctob_l(c, __l);
+    return r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
+}
+
+const wchar_t*
+ctype_byname<wchar_t>::do_narrow(const char_type* low, const char_type* high, char dfault, char* dest) const
+{
+    for (; low != high; ++low, ++dest)
+    {
+        int r = __libcpp_wctob_l(*low, __l);
+        *dest = r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
+    }
+    return low;
+}
+
+// template <> class codecvt<char, char, mbstate_t>
+
+locale::id codecvt<char, char, mbstate_t>::id;
+
+codecvt<char, char, mbstate_t>::~codecvt()
+{
+}
+
+codecvt<char, char, mbstate_t>::result
+codecvt<char, char, mbstate_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type*, const intern_type*& frm_nxt,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    return noconv;
+}
+
+codecvt<char, char, mbstate_t>::result
+codecvt<char, char, mbstate_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type*, const extern_type*& frm_nxt,
+    intern_type* to, intern_type*, intern_type*& to_nxt) const
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    return noconv;
+}
+
+codecvt<char, char, mbstate_t>::result
+codecvt<char, char, mbstate_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+codecvt<char, char, mbstate_t>::do_encoding() const  _NOEXCEPT
+{
+    return 1;
+}
+
+bool
+codecvt<char, char, mbstate_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return true;
+}
+
+int
+codecvt<char, char, mbstate_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* end, size_t mx) const
+{
+    return static_cast<int>(min<size_t>(mx, static_cast<size_t>(end-frm)));
+}
+
+int
+codecvt<char, char, mbstate_t>::do_max_length() const  _NOEXCEPT
+{
+    return 1;
+}
+
+// template <> class codecvt<wchar_t, char, mbstate_t>
+
+locale::id codecvt<wchar_t, char, mbstate_t>::id;
+
+codecvt<wchar_t, char, mbstate_t>::codecvt(size_t refs)
+    : locale::facet(refs),
+      __l(_LIBCPP_GET_C_LOCALE)
+{
+}
+
+codecvt<wchar_t, char, mbstate_t>::codecvt(const char* nm, size_t refs)
+    : locale::facet(refs),
+      __l(newlocale(LC_ALL_MASK, nm, 0))
+{
+    if (__l == 0)
+        __throw_runtime_error("codecvt_byname<wchar_t, char, mbstate_t>::codecvt_byname"
+                            " failed to construct for " + string(nm));
+}
+
+codecvt<wchar_t, char, mbstate_t>::~codecvt()
+{
+    if (__l != _LIBCPP_GET_C_LOCALE)
+        freelocale(__l);
+}
+
+codecvt<wchar_t, char, mbstate_t>::result
+codecvt<wchar_t, char, mbstate_t>::do_out(state_type& st,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    // look for first internal null in frm
+    const intern_type* fend = frm;
+    for (; fend != frm_end; ++fend)
+        if (*fend == 0)
+            break;
+    // loop over all null-terminated sequences in frm
+    to_nxt = to;
+    for (frm_nxt = frm; frm != frm_end && to != to_end; frm = frm_nxt, to = to_nxt)
+    {
+        // save state in case it is needed to recover to_nxt on error
+        mbstate_t save_state = st;
+        size_t n = __libcpp_wcsnrtombs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
+                                     static_cast<size_t>(to_end-to), &st, __l);
+        if (n == size_t(-1))
+        {
+            // need to recover to_nxt
+            for (to_nxt = to; frm != frm_nxt; ++frm)
+            {
+                n = __libcpp_wcrtomb_l(to_nxt, *frm, &save_state, __l);
+                if (n == size_t(-1))
+                    break;
+                to_nxt += n;
+            }
+            frm_nxt = frm;
+            return error;
+        }
+        if (n == 0)
+            return partial;
+        to_nxt += n;
+        if (to_nxt == to_end)
+            break;
+        if (fend != frm_end)  // set up next null terminated sequence
+        {
+            // Try to write the terminating null
+            extern_type tmp[MB_LEN_MAX];
+            n = __libcpp_wcrtomb_l(tmp, intern_type(), &st, __l);
+            if (n == size_t(-1))  // on error
+                return error;
+            if (n > static_cast<size_t>(to_end-to_nxt))  // is there room?
+                return partial;
+            for (extern_type* p = tmp; n; --n)  // write it
+                *to_nxt++ = *p++;
+            ++frm_nxt;
+            // look for next null in frm
+            for (fend = frm_nxt; fend != frm_end; ++fend)
+                if (*fend == 0)
+                    break;
+        }
+    }
+    return frm_nxt == frm_end ? ok : partial;
+}
+
+codecvt<wchar_t, char, mbstate_t>::result
+codecvt<wchar_t, char, mbstate_t>::do_in(state_type& st,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    // look for first internal null in frm
+    const extern_type* fend = frm;
+    for (; fend != frm_end; ++fend)
+        if (*fend == 0)
+            break;
+    // loop over all null-terminated sequences in frm
+    to_nxt = to;
+    for (frm_nxt = frm; frm != frm_end && to != to_end; frm = frm_nxt, to = to_nxt)
+    {
+        // save state in case it is needed to recover to_nxt on error
+        mbstate_t save_state = st;
+        size_t n = __libcpp_mbsnrtowcs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
+                                     static_cast<size_t>(to_end-to), &st, __l);
+        if (n == size_t(-1))
+        {
+            // need to recover to_nxt
+            for (to_nxt = to; frm != frm_nxt; ++to_nxt)
+            {
+                n = __libcpp_mbrtowc_l(to_nxt, frm, static_cast<size_t>(fend-frm),
+                                   &save_state, __l);
+                switch (n)
+                {
+                case 0:
+                    ++frm;
+                    break;
+                case size_t(-1):
+                    frm_nxt = frm;
+                    return error;
+                case size_t(-2):
+                    frm_nxt = frm;
+                    return partial;
+                default:
+                    frm += n;
+                    break;
+                }
+            }
+            frm_nxt = frm;
+            return frm_nxt == frm_end ? ok : partial;
+        }
+        if (n == size_t(-1))
+            return error;
+        to_nxt += n;
+        if (to_nxt == to_end)
+            break;
+        if (fend != frm_end)  // set up next null terminated sequence
+        {
+            // Try to write the terminating null
+            n = __libcpp_mbrtowc_l(to_nxt, frm_nxt, 1, &st, __l);
+            if (n != 0)  // on error
+                return error;
+            ++to_nxt;
+            ++frm_nxt;
+            // look for next null in frm
+            for (fend = frm_nxt; fend != frm_end; ++fend)
+                if (*fend == 0)
+                    break;
+        }
+    }
+    return frm_nxt == frm_end ? ok : partial;
+}
+
+codecvt<wchar_t, char, mbstate_t>::result
+codecvt<wchar_t, char, mbstate_t>::do_unshift(state_type& st,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    extern_type tmp[MB_LEN_MAX];
+    size_t n = __libcpp_wcrtomb_l(tmp, intern_type(), &st, __l);
+    if (n == size_t(-1) || n == 0)  // on error
+        return error;
+    --n;
+    if (n > static_cast<size_t>(to_end-to_nxt))  // is there room?
+        return partial;
+    for (extern_type* p = tmp; n; --n)  // write it
+        *to_nxt++ = *p++;
+    return ok;
+}
+
+int
+codecvt<wchar_t, char, mbstate_t>::do_encoding() const  _NOEXCEPT
+{
+    if (__libcpp_mbtowc_l(nullptr, nullptr, MB_LEN_MAX, __l) != 0)
+        return -1;
+
+    // stateless encoding
+    if (__l == 0 || __libcpp_mb_cur_max_l(__l) == 1)  // there are no known constant length encodings
+        return 1;                // which take more than 1 char to form a wchar_t
+    return 0;
+}
+
+bool
+codecvt<wchar_t, char, mbstate_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+codecvt<wchar_t, char, mbstate_t>::do_length(state_type& st,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    int nbytes = 0;
+    for (size_t nwchar_t = 0; nwchar_t < mx && frm != frm_end; ++nwchar_t)
+    {
+        size_t n = __libcpp_mbrlen_l(frm, static_cast<size_t>(frm_end-frm), &st, __l);
+        switch (n)
+        {
+        case 0:
+            ++nbytes;
+            ++frm;
+            break;
+        case size_t(-1):
+        case size_t(-2):
+            return nbytes;
+        default:
+            nbytes += n;
+            frm += n;
+            break;
+        }
+    }
+    return nbytes;
+}
+
+int
+codecvt<wchar_t, char, mbstate_t>::do_max_length() const  _NOEXCEPT
+{
+    return __l == 0 ? 1 : static_cast<int>(__libcpp_mb_cur_max_l(__l));
+}
+
+//                                     Valid UTF ranges
+//     UTF-32               UTF-16                          UTF-8               # of code points
+//                     first      second       first   second    third   fourth
+// 000000 - 00007F  0000 - 007F               00 - 7F                                 127
+// 000080 - 0007FF  0080 - 07FF               C2 - DF, 80 - BF                       1920
+// 000800 - 000FFF  0800 - 0FFF               E0 - E0, A0 - BF, 80 - BF              2048
+// 001000 - 00CFFF  1000 - CFFF               E1 - EC, 80 - BF, 80 - BF             49152
+// 00D000 - 00D7FF  D000 - D7FF               ED - ED, 80 - 9F, 80 - BF              2048
+// 00D800 - 00DFFF                invalid
+// 00E000 - 00FFFF  E000 - FFFF               EE - EF, 80 - BF, 80 - BF              8192
+// 010000 - 03FFFF  D800 - D8BF, DC00 - DFFF  F0 - F0, 90 - BF, 80 - BF, 80 - BF   196608
+// 040000 - 0FFFFF  D8C0 - DBBF, DC00 - DFFF  F1 - F3, 80 - BF, 80 - BF, 80 - BF   786432
+// 100000 - 10FFFF  DBC0 - DBFF, DC00 - DFFF  F4 - F4, 80 - 8F, 80 - BF, 80 - BF    65536
+
+static
+codecvt_base::result
+utf16_to_utf8(const uint16_t* frm, const uint16_t* frm_end, const uint16_t*& frm_nxt,
+              uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+              unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 3)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xEF);
+        *to_nxt++ = static_cast<uint8_t>(0xBB);
+        *to_nxt++ = static_cast<uint8_t>(0xBF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint16_t wc1 = *frm_nxt;
+        if (wc1 > Maxcode)
+            return codecvt_base::error;
+        if (wc1 < 0x0080)
+        {
+            if (to_end-to_nxt < 1)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc1);
+        }
+        else if (wc1 < 0x0800)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xC0 | (wc1 >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | (wc1 & 0x03F));
+        }
+        else if (wc1 < 0xD800)
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc1 >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc1 & 0x003F));
+        }
+        else if (wc1 < 0xDC00)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint16_t wc2 = frm_nxt[1];
+            if ((wc2 & 0xFC00) != 0xDC00)
+                return codecvt_base::error;
+            if (to_end-to_nxt < 4)
+                return codecvt_base::partial;
+            if (((((wc1 & 0x03C0UL) >> 6) + 1) << 16) +
+                ((wc1 & 0x003FUL) << 10) + (wc2 & 0x03FF) > Maxcode)
+                return codecvt_base::error;
+            ++frm_nxt;
+            uint8_t z = ((wc1 & 0x03C0) >> 6) + 1;
+            *to_nxt++ = static_cast<uint8_t>(0xF0 | (z >> 2));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((z & 0x03) << 4)     | ((wc1 & 0x003C) >> 2));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0003) << 4) | ((wc2 & 0x03C0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc2 & 0x003F));
+        }
+        else if (wc1 < 0xE000)
+        {
+            return codecvt_base::error;
+        }
+        else
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc1 >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc1 & 0x003F));
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf16_to_utf8(const uint32_t* frm, const uint32_t* frm_end, const uint32_t*& frm_nxt,
+              uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+              unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 3)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xEF);
+        *to_nxt++ = static_cast<uint8_t>(0xBB);
+        *to_nxt++ = static_cast<uint8_t>(0xBF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint16_t wc1 = static_cast<uint16_t>(*frm_nxt);
+        if (wc1 > Maxcode)
+            return codecvt_base::error;
+        if (wc1 < 0x0080)
+        {
+            if (to_end-to_nxt < 1)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc1);
+        }
+        else if (wc1 < 0x0800)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xC0 | (wc1 >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | (wc1 & 0x03F));
+        }
+        else if (wc1 < 0xD800)
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc1 >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc1 & 0x003F));
+        }
+        else if (wc1 < 0xDC00)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint16_t wc2 = static_cast<uint16_t>(frm_nxt[1]);
+            if ((wc2 & 0xFC00) != 0xDC00)
+                return codecvt_base::error;
+            if (to_end-to_nxt < 4)
+                return codecvt_base::partial;
+            if (((((wc1 & 0x03C0UL) >> 6) + 1) << 16) +
+                ((wc1 & 0x003FUL) << 10) + (wc2 & 0x03FF) > Maxcode)
+                return codecvt_base::error;
+            ++frm_nxt;
+            uint8_t z = ((wc1 & 0x03C0) >> 6) + 1;
+            *to_nxt++ = static_cast<uint8_t>(0xF0 | (z >> 2));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((z & 0x03) << 4)     | ((wc1 & 0x003C) >> 2));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0003) << 4) | ((wc2 & 0x03C0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc2 & 0x003F));
+        }
+        else if (wc1 < 0xE000)
+        {
+            return codecvt_base::error;
+        }
+        else
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc1 >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc1 & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc1 & 0x003F));
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf8_to_utf16(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+              uint16_t* to, uint16_t* to_end, uint16_t*& to_nxt,
+              unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (; frm_nxt < frm_end && to_nxt < to_end; ++to_nxt)
+    {
+        uint8_t c1 = *frm_nxt;
+        if (c1 > Maxcode)
+            return codecvt_base::error;
+        if (c1 < 0x80)
+        {
+            *to_nxt = static_cast<uint16_t>(c1);
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            return codecvt_base::error;
+        }
+        else if (c1 < 0xE0)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            if ((c2 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x1F) << 6) | (c2 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return codecvt_base::error;
+                 break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x0F) << 12)
+                                             | ((c2 & 0x3F) << 6)
+                                             |  (c3 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 3;
+        }
+        else if (c1 < 0xF5)
+        {
+            if (frm_end-frm_nxt < 4)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            uint8_t c4 = frm_nxt[3];
+            switch (c1)
+            {
+            case 0xF0:
+                if (!(0x90 <= c2 && c2 <= 0xBF))
+                    return codecvt_base::error;
+                 break;
+            case 0xF4:
+                if ((c2 & 0xF0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80 || (c4 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            if ((((c1 & 7UL) << 18) +
+                ((c2 & 0x3FUL) << 12) +
+                ((c3 & 0x3FUL) << 6) + (c4 & 0x3F)) > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint16_t>(
+                    0xD800
+                  | (((((c1 & 0x07) << 2) | ((c2 & 0x30) >> 4)) - 1) << 6)
+                  | ((c2 & 0x0F) << 2)
+                  | ((c3 & 0x30) >> 4));
+            *++to_nxt = static_cast<uint16_t>(
+                    0xDC00
+                  | ((c3 & 0x0F) << 6)
+                  |  (c4 & 0x3F));
+            frm_nxt += 4;
+        }
+        else
+        {
+            return codecvt_base::error;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf8_to_utf16(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+              uint32_t* to, uint32_t* to_end, uint32_t*& to_nxt,
+              unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (; frm_nxt < frm_end && to_nxt < to_end; ++to_nxt)
+    {
+        uint8_t c1 = *frm_nxt;
+        if (c1 > Maxcode)
+            return codecvt_base::error;
+        if (c1 < 0x80)
+        {
+            *to_nxt = static_cast<uint32_t>(c1);
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            return codecvt_base::error;
+        }
+        else if (c1 < 0xE0)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            if ((c2 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x1F) << 6) | (c2 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(t);
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return codecvt_base::error;
+                 break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x0F) << 12)
+                                             | ((c2 & 0x3F) << 6)
+                                             |  (c3 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(t);
+            frm_nxt += 3;
+        }
+        else if (c1 < 0xF5)
+        {
+            if (frm_end-frm_nxt < 4)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            uint8_t c4 = frm_nxt[3];
+            switch (c1)
+            {
+            case 0xF0:
+                if (!(0x90 <= c2 && c2 <= 0xBF))
+                    return codecvt_base::error;
+                 break;
+            case 0xF4:
+                if ((c2 & 0xF0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80 || (c4 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            if ((((c1 & 7UL) << 18) +
+                ((c2 & 0x3FUL) << 12) +
+                ((c3 & 0x3FUL) << 6) + (c4 & 0x3F)) > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(
+                    0xD800
+                  | (((((c1 & 0x07) << 2) | ((c2 & 0x30) >> 4)) - 1) << 6)
+                  | ((c2 & 0x0F) << 2)
+                  | ((c3 & 0x30) >> 4));
+            *++to_nxt = static_cast<uint32_t>(
+                    0xDC00
+                  | ((c3 & 0x0F) << 6)
+                  |  (c4 & 0x3F));
+            frm_nxt += 4;
+        }
+        else
+        {
+            return codecvt_base::error;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf8_to_utf16_length(const uint8_t* frm, const uint8_t* frm_end,
+                     size_t mx, unsigned long Maxcode = 0x10FFFF,
+                     codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (size_t nchar16_t = 0; frm_nxt < frm_end && nchar16_t < mx; ++nchar16_t)
+    {
+        uint8_t c1 = *frm_nxt;
+        if (c1 > Maxcode)
+            break;
+        if (c1 < 0x80)
+        {
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            break;
+        }
+        else if (c1 < 0xE0)
+        {
+            if ((frm_end-frm_nxt < 2) || (frm_nxt[1] & 0xC0) != 0x80)
+                break;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x1F) << 6) | (frm_nxt[1] & 0x3F));
+            if (t > Maxcode)
+                break;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                break;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return static_cast<int>(frm_nxt - frm);
+                break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                break;
+            if ((((c1 & 0x0Fu) << 12) | ((c2 & 0x3Fu) << 6) | (c3 & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 3;
+        }
+        else if (c1 < 0xF5)
+        {
+            if (frm_end-frm_nxt < 4 || mx-nchar16_t < 2)
+                break;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            uint8_t c4 = frm_nxt[3];
+            switch (c1)
+            {
+            case 0xF0:
+                if (!(0x90 <= c2 && c2 <= 0xBF))
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            case 0xF4:
+                if ((c2 & 0xF0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80 || (c4 & 0xC0) != 0x80)
+                break;
+            if ((((c1 & 7UL) << 18) +
+                ((c2 & 0x3FUL) << 12) +
+                ((c3 & 0x3FUL) << 6) + (c4 & 0x3F)) > Maxcode)
+                break;
+            ++nchar16_t;
+            frm_nxt += 4;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs4_to_utf8(const uint32_t* frm, const uint32_t* frm_end, const uint32_t*& frm_nxt,
+             uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+             unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 3)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xEF);
+        *to_nxt++ = static_cast<uint8_t>(0xBB);
+        *to_nxt++ = static_cast<uint8_t>(0xBF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint32_t wc = *frm_nxt;
+        if ((wc & 0xFFFFF800) == 0x00D800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (wc < 0x000080)
+        {
+            if (to_end-to_nxt < 1)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc);
+        }
+        else if (wc < 0x000800)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xC0 | (wc >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | (wc & 0x03F));
+        }
+        else if (wc < 0x010000)
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc & 0x003F));
+        }
+        else // if (wc < 0x110000)
+        {
+            if (to_end-to_nxt < 4)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xF0 |  (wc >> 18));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc & 0x03F000) >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc & 0x000FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc & 0x00003F));
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf8_to_ucs4(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+             uint32_t* to, uint32_t* to_end, uint32_t*& to_nxt,
+             unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (; frm_nxt < frm_end && to_nxt < to_end; ++to_nxt)
+    {
+        uint8_t c1 = static_cast<uint8_t>(*frm_nxt);
+        if (c1 < 0x80)
+        {
+            if (c1 > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(c1);
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            return codecvt_base::error;
+        }
+        else if (c1 < 0xE0)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            if ((c2 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint32_t t = static_cast<uint32_t>(((c1 & 0x1F) << 6)
+                                              | (c2 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return codecvt_base::error;
+                 break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint32_t t = static_cast<uint32_t>(((c1 & 0x0F) << 12)
+                                             | ((c2 & 0x3F) << 6)
+                                             |  (c3 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 3;
+        }
+        else if (c1 < 0xF5)
+        {
+            if (frm_end-frm_nxt < 4)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            uint8_t c4 = frm_nxt[3];
+            switch (c1)
+            {
+            case 0xF0:
+                if (!(0x90 <= c2 && c2 <= 0xBF))
+                    return codecvt_base::error;
+                 break;
+            case 0xF4:
+                if ((c2 & 0xF0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80 || (c4 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint32_t t = static_cast<uint32_t>(((c1 & 0x07) << 18)
+                                             | ((c2 & 0x3F) << 12)
+                                             | ((c3 & 0x3F) << 6)
+                                             |  (c4 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 4;
+        }
+        else
+        {
+            return codecvt_base::error;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf8_to_ucs4_length(const uint8_t* frm, const uint8_t* frm_end,
+                    size_t mx, unsigned long Maxcode = 0x10FFFF,
+                    codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (size_t nchar32_t = 0; frm_nxt < frm_end && nchar32_t < mx; ++nchar32_t)
+    {
+        uint8_t c1 = static_cast<uint8_t>(*frm_nxt);
+        if (c1 < 0x80)
+        {
+            if (c1 > Maxcode)
+                break;
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            break;
+        }
+        else if (c1 < 0xE0)
+        {
+            if ((frm_end-frm_nxt < 2) || ((frm_nxt[1] & 0xC0) != 0x80))
+                break;
+            if ((((c1 & 0x1Fu) << 6) | (frm_nxt[1] & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                break;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return static_cast<int>(frm_nxt - frm);
+                break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                break;
+            if ((((c1 & 0x0Fu) << 12) | ((c2 & 0x3Fu) << 6) | (c3 & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 3;
+        }
+        else if (c1 < 0xF5)
+        {
+            if (frm_end-frm_nxt < 4)
+                break;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            uint8_t c4 = frm_nxt[3];
+            switch (c1)
+            {
+            case 0xF0:
+                if (!(0x90 <= c2 && c2 <= 0xBF))
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            case 0xF4:
+                if ((c2 & 0xF0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80 || (c4 & 0xC0) != 0x80)
+                break;
+            if ((((c1 & 0x07u) << 18) | ((c2 & 0x3Fu) << 12) |
+                 ((c3 & 0x3Fu) << 6)  |  (c4 & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 4;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs2_to_utf8(const uint16_t* frm, const uint16_t* frm_end, const uint16_t*& frm_nxt,
+             uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+             unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 3)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xEF);
+        *to_nxt++ = static_cast<uint8_t>(0xBB);
+        *to_nxt++ = static_cast<uint8_t>(0xBF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint16_t wc = *frm_nxt;
+        if ((wc & 0xF800) == 0xD800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (wc < 0x0080)
+        {
+            if (to_end-to_nxt < 1)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc);
+        }
+        else if (wc < 0x0800)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xC0 | (wc >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | (wc & 0x03F));
+        }
+        else // if (wc <= 0xFFFF)
+        {
+            if (to_end-to_nxt < 3)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(0xE0 |  (wc >> 12));
+            *to_nxt++ = static_cast<uint8_t>(0x80 | ((wc & 0x0FC0) >> 6));
+            *to_nxt++ = static_cast<uint8_t>(0x80 |  (wc & 0x003F));
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf8_to_ucs2(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+             uint16_t* to, uint16_t* to_end, uint16_t*& to_nxt,
+             unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (; frm_nxt < frm_end && to_nxt < to_end; ++to_nxt)
+    {
+        uint8_t c1 = static_cast<uint8_t>(*frm_nxt);
+        if (c1 < 0x80)
+        {
+            if (c1 > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint16_t>(c1);
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            return codecvt_base::error;
+        }
+        else if (c1 < 0xE0)
+        {
+            if (frm_end-frm_nxt < 2)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            if ((c2 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x1F) << 6)
+                                              | (c2 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                return codecvt_base::partial;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return codecvt_base::error;
+                 break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return codecvt_base::error;
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                return codecvt_base::error;
+            uint16_t t = static_cast<uint16_t>(((c1 & 0x0F) << 12)
+                                             | ((c2 & 0x3F) << 6)
+                                             |  (c3 & 0x3F));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 3;
+        }
+        else
+        {
+            return codecvt_base::error;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf8_to_ucs2_length(const uint8_t* frm, const uint8_t* frm_end,
+                    size_t mx, unsigned long Maxcode = 0x10FFFF,
+                    codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 3 && frm_nxt[0] == 0xEF && frm_nxt[1] == 0xBB &&
+                                                          frm_nxt[2] == 0xBF)
+            frm_nxt += 3;
+    }
+    for (size_t nchar32_t = 0; frm_nxt < frm_end && nchar32_t < mx; ++nchar32_t)
+    {
+        uint8_t c1 = static_cast<uint8_t>(*frm_nxt);
+        if (c1 < 0x80)
+        {
+            if (c1 > Maxcode)
+                break;
+            ++frm_nxt;
+        }
+        else if (c1 < 0xC2)
+        {
+            break;
+        }
+        else if (c1 < 0xE0)
+        {
+            if ((frm_end-frm_nxt < 2) || ((frm_nxt[1] & 0xC0) != 0x80))
+                break;
+            if ((((c1 & 0x1Fu) << 6) | (frm_nxt[1] & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 2;
+        }
+        else if (c1 < 0xF0)
+        {
+            if (frm_end-frm_nxt < 3)
+                break;
+            uint8_t c2 = frm_nxt[1];
+            uint8_t c3 = frm_nxt[2];
+            switch (c1)
+            {
+            case 0xE0:
+                if ((c2 & 0xE0) != 0xA0)
+                    return static_cast<int>(frm_nxt - frm);
+                break;
+            case 0xED:
+                if ((c2 & 0xE0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            default:
+                if ((c2 & 0xC0) != 0x80)
+                    return static_cast<int>(frm_nxt - frm);
+                 break;
+            }
+            if ((c3 & 0xC0) != 0x80)
+                break;
+            if ((((c1 & 0x0Fu) << 12) | ((c2 & 0x3Fu) << 6) | (c3 & 0x3Fu)) > Maxcode)
+                break;
+            frm_nxt += 3;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs4_to_utf16be(const uint32_t* frm, const uint32_t* frm_end, const uint32_t*& frm_nxt,
+                uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xFE);
+        *to_nxt++ = static_cast<uint8_t>(0xFF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint32_t wc = *frm_nxt;
+        if ((wc & 0xFFFFF800) == 0x00D800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (wc < 0x010000)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc >> 8);
+            *to_nxt++ = static_cast<uint8_t>(wc);
+        }
+        else
+        {
+            if (to_end-to_nxt < 4)
+                return codecvt_base::partial;
+            uint16_t t = static_cast<uint16_t>(
+                    0xD800
+                  | ((((wc & 0x1F0000) >> 16) - 1) << 6)
+                  |   ((wc & 0x00FC00) >> 10));
+            *to_nxt++ = static_cast<uint8_t>(t >> 8);
+            *to_nxt++ = static_cast<uint8_t>(t);
+            t = static_cast<uint16_t>(0xDC00 | (wc & 0x03FF));
+            *to_nxt++ = static_cast<uint8_t>(t >> 8);
+            *to_nxt++ = static_cast<uint8_t>(t);
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf16be_to_ucs4(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+                uint32_t* to, uint32_t* to_end, uint32_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFE && frm_nxt[1] == 0xFF)
+            frm_nxt += 2;
+    }
+    for (; frm_nxt < frm_end - 1 && to_nxt < to_end; ++to_nxt)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[0] << 8 | frm_nxt[1]);
+        if ((c1 & 0xFC00) == 0xDC00)
+            return codecvt_base::error;
+        if ((c1 & 0xFC00) != 0xD800)
+        {
+            if (c1 > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(c1);
+            frm_nxt += 2;
+        }
+        else
+        {
+            if (frm_end-frm_nxt < 4)
+                return codecvt_base::partial;
+            uint16_t c2 = static_cast<uint16_t>(frm_nxt[2] << 8 | frm_nxt[3]);
+            if ((c2 & 0xFC00) != 0xDC00)
+                return codecvt_base::error;
+            uint32_t t = static_cast<uint32_t>(
+                    ((((c1 & 0x03C0) >> 6) + 1) << 16)
+                  |   ((c1 & 0x003F) << 10)
+                  |    (c2 & 0x03FF));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 4;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf16be_to_ucs4_length(const uint8_t* frm, const uint8_t* frm_end,
+                       size_t mx, unsigned long Maxcode = 0x10FFFF,
+                       codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFE && frm_nxt[1] == 0xFF)
+            frm_nxt += 2;
+    }
+    for (size_t nchar32_t = 0; frm_nxt < frm_end - 1 && nchar32_t < mx; ++nchar32_t)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[0] << 8 | frm_nxt[1]);
+        if ((c1 & 0xFC00) == 0xDC00)
+            break;
+        if ((c1 & 0xFC00) != 0xD800)
+        {
+            if (c1 > Maxcode)
+                break;
+            frm_nxt += 2;
+        }
+        else
+        {
+            if (frm_end-frm_nxt < 4)
+                break;
+            uint16_t c2 = static_cast<uint16_t>(frm_nxt[2] << 8 | frm_nxt[3]);
+            if ((c2 & 0xFC00) != 0xDC00)
+                break;
+            uint32_t t = static_cast<uint32_t>(
+                    ((((c1 & 0x03C0) >> 6) + 1) << 16)
+                  |   ((c1 & 0x003F) << 10)
+                  |    (c2 & 0x03FF));
+            if (t > Maxcode)
+                break;
+            frm_nxt += 4;
+        }
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs4_to_utf16le(const uint32_t* frm, const uint32_t* frm_end, const uint32_t*& frm_nxt,
+                uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end - to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xFF);
+        *to_nxt++ = static_cast<uint8_t>(0xFE);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint32_t wc = *frm_nxt;
+        if ((wc & 0xFFFFF800) == 0x00D800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (wc < 0x010000)
+        {
+            if (to_end-to_nxt < 2)
+                return codecvt_base::partial;
+            *to_nxt++ = static_cast<uint8_t>(wc);
+            *to_nxt++ = static_cast<uint8_t>(wc >> 8);
+        }
+        else
+        {
+            if (to_end-to_nxt < 4)
+                return codecvt_base::partial;
+            uint16_t t = static_cast<uint16_t>(
+                    0xD800
+                  | ((((wc & 0x1F0000) >> 16) - 1) << 6)
+                  |   ((wc & 0x00FC00) >> 10));
+            *to_nxt++ = static_cast<uint8_t>(t);
+            *to_nxt++ = static_cast<uint8_t>(t >> 8);
+            t = static_cast<uint16_t>(0xDC00 | (wc & 0x03FF));
+            *to_nxt++ = static_cast<uint8_t>(t);
+            *to_nxt++ = static_cast<uint8_t>(t >> 8);
+        }
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf16le_to_ucs4(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+                uint32_t* to, uint32_t* to_end, uint32_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFF && frm_nxt[1] == 0xFE)
+            frm_nxt += 2;
+    }
+    for (; frm_nxt < frm_end - 1 && to_nxt < to_end; ++to_nxt)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[1] << 8 | frm_nxt[0]);
+        if ((c1 & 0xFC00) == 0xDC00)
+            return codecvt_base::error;
+        if ((c1 & 0xFC00) != 0xD800)
+        {
+            if (c1 > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = static_cast<uint32_t>(c1);
+            frm_nxt += 2;
+        }
+        else
+        {
+            if (frm_end-frm_nxt < 4)
+                return codecvt_base::partial;
+            uint16_t c2 = static_cast<uint16_t>(frm_nxt[3] << 8 | frm_nxt[2]);
+            if ((c2 & 0xFC00) != 0xDC00)
+                return codecvt_base::error;
+            uint32_t t = static_cast<uint32_t>(
+                    ((((c1 & 0x03C0) >> 6) + 1) << 16)
+                  |   ((c1 & 0x003F) << 10)
+                  |    (c2 & 0x03FF));
+            if (t > Maxcode)
+                return codecvt_base::error;
+            *to_nxt = t;
+            frm_nxt += 4;
+        }
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf16le_to_ucs4_length(const uint8_t* frm, const uint8_t* frm_end,
+                       size_t mx, unsigned long Maxcode = 0x10FFFF,
+                       codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFF && frm_nxt[1] == 0xFE)
+            frm_nxt += 2;
+    }
+    for (size_t nchar32_t = 0; frm_nxt < frm_end - 1 && nchar32_t < mx; ++nchar32_t)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[1] << 8 | frm_nxt[0]);
+        if ((c1 & 0xFC00) == 0xDC00)
+            break;
+        if ((c1 & 0xFC00) != 0xD800)
+        {
+            if (c1 > Maxcode)
+                break;
+            frm_nxt += 2;
+        }
+        else
+        {
+            if (frm_end-frm_nxt < 4)
+                break;
+            uint16_t c2 = static_cast<uint16_t>(frm_nxt[3] << 8 | frm_nxt[2]);
+            if ((c2 & 0xFC00) != 0xDC00)
+                break;
+            uint32_t t = static_cast<uint32_t>(
+                    ((((c1 & 0x03C0) >> 6) + 1) << 16)
+                  |   ((c1 & 0x003F) << 10)
+                  |    (c2 & 0x03FF));
+            if (t > Maxcode)
+                break;
+            frm_nxt += 4;
+        }
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs2_to_utf16be(const uint16_t* frm, const uint16_t* frm_end, const uint16_t*& frm_nxt,
+                uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xFE);
+        *to_nxt++ = static_cast<uint8_t>(0xFF);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint16_t wc = *frm_nxt;
+        if ((wc & 0xF800) == 0xD800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (to_end-to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(wc >> 8);
+        *to_nxt++ = static_cast<uint8_t>(wc);
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf16be_to_ucs2(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+                uint16_t* to, uint16_t* to_end, uint16_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFE && frm_nxt[1] == 0xFF)
+            frm_nxt += 2;
+    }
+    for (; frm_nxt < frm_end - 1 && to_nxt < to_end; ++to_nxt)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[0] << 8 | frm_nxt[1]);
+        if ((c1 & 0xF800) == 0xD800 || c1 > Maxcode)
+            return codecvt_base::error;
+        *to_nxt = c1;
+        frm_nxt += 2;
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf16be_to_ucs2_length(const uint8_t* frm, const uint8_t* frm_end,
+                       size_t mx, unsigned long Maxcode = 0x10FFFF,
+                       codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFE && frm_nxt[1] == 0xFF)
+            frm_nxt += 2;
+    }
+    for (size_t nchar16_t = 0; frm_nxt < frm_end - 1 && nchar16_t < mx; ++nchar16_t)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[0] << 8 | frm_nxt[1]);
+        if ((c1 & 0xF800) == 0xD800 || c1 > Maxcode)
+            break;
+        frm_nxt += 2;
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+static
+codecvt_base::result
+ucs2_to_utf16le(const uint16_t* frm, const uint16_t* frm_end, const uint16_t*& frm_nxt,
+                uint8_t* to, uint8_t* to_end, uint8_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & generate_header)
+    {
+        if (to_end-to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(0xFF);
+        *to_nxt++ = static_cast<uint8_t>(0xFE);
+    }
+    for (; frm_nxt < frm_end; ++frm_nxt)
+    {
+        uint16_t wc = *frm_nxt;
+        if ((wc & 0xF800) == 0xD800 || wc > Maxcode)
+            return codecvt_base::error;
+        if (to_end-to_nxt < 2)
+            return codecvt_base::partial;
+        *to_nxt++ = static_cast<uint8_t>(wc);
+        *to_nxt++ = static_cast<uint8_t>(wc >> 8);
+    }
+    return codecvt_base::ok;
+}
+
+static
+codecvt_base::result
+utf16le_to_ucs2(const uint8_t* frm, const uint8_t* frm_end, const uint8_t*& frm_nxt,
+                uint16_t* to, uint16_t* to_end, uint16_t*& to_nxt,
+                unsigned long Maxcode = 0x10FFFF, codecvt_mode mode = codecvt_mode(0))
+{
+    frm_nxt = frm;
+    to_nxt = to;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFF && frm_nxt[1] == 0xFE)
+            frm_nxt += 2;
+    }
+    for (; frm_nxt < frm_end - 1 && to_nxt < to_end; ++to_nxt)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[1] << 8 | frm_nxt[0]);
+        if ((c1 & 0xF800) == 0xD800 || c1 > Maxcode)
+            return codecvt_base::error;
+        *to_nxt = c1;
+        frm_nxt += 2;
+    }
+    return frm_nxt < frm_end ? codecvt_base::partial : codecvt_base::ok;
+}
+
+static
+int
+utf16le_to_ucs2_length(const uint8_t* frm, const uint8_t* frm_end,
+                       size_t mx, unsigned long Maxcode = 0x10FFFF,
+                       codecvt_mode mode = codecvt_mode(0))
+{
+    const uint8_t* frm_nxt = frm;
+    frm_nxt = frm;
+    if (mode & consume_header)
+    {
+        if (frm_end-frm_nxt >= 2 && frm_nxt[0] == 0xFF && frm_nxt[1] == 0xFE)
+            frm_nxt += 2;
+    }
+    for (size_t nchar16_t = 0; frm_nxt < frm_end - 1 && nchar16_t < mx; ++nchar16_t)
+    {
+        uint16_t c1 = static_cast<uint16_t>(frm_nxt[1] << 8 | frm_nxt[0]);
+        if ((c1 & 0xF800) == 0xD800 || c1 > Maxcode)
+            break;
+        frm_nxt += 2;
+    }
+    return static_cast<int>(frm_nxt - frm);
+}
+
+// template <> class codecvt<char16_t, char, mbstate_t>
+
+locale::id codecvt<char16_t, char, mbstate_t>::id;
+
+codecvt<char16_t, char, mbstate_t>::~codecvt()
+{
+}
+
+codecvt<char16_t, char, mbstate_t>::result
+codecvt<char16_t, char, mbstate_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = utf16_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+codecvt<char16_t, char, mbstate_t>::result
+codecvt<char16_t, char, mbstate_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf8_to_utf16(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+codecvt<char16_t, char, mbstate_t>::result
+codecvt<char16_t, char, mbstate_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+codecvt<char16_t, char, mbstate_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+codecvt<char16_t, char, mbstate_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+codecvt<char16_t, char, mbstate_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_utf16_length(_frm, _frm_end, mx);
+}
+
+int
+codecvt<char16_t, char, mbstate_t>::do_max_length() const  _NOEXCEPT
+{
+    return 4;
+}
+
+// template <> class codecvt<char32_t, char, mbstate_t>
+
+locale::id codecvt<char32_t, char, mbstate_t>::id;
+
+codecvt<char32_t, char, mbstate_t>::~codecvt()
+{
+}
+
+codecvt<char32_t, char, mbstate_t>::result
+codecvt<char32_t, char, mbstate_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+codecvt<char32_t, char, mbstate_t>::result
+codecvt<char32_t, char, mbstate_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf8_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+codecvt<char32_t, char, mbstate_t>::result
+codecvt<char32_t, char, mbstate_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+codecvt<char32_t, char, mbstate_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+codecvt<char32_t, char, mbstate_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+codecvt<char32_t, char, mbstate_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_ucs4_length(_frm, _frm_end, mx);
+}
+
+int
+codecvt<char32_t, char, mbstate_t>::do_max_length() const  _NOEXCEPT
+{
+    return 4;
+}
+
+// __codecvt_utf8<wchar_t>
+
+__codecvt_utf8<wchar_t>::result
+__codecvt_utf8<wchar_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+#if defined(_LIBCPP_SHORT_WCHAR)
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+#else
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+#endif
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+#if defined(_LIBCPP_SHORT_WCHAR)
+    result r = ucs2_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+#else
+    result r = ucs4_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+#endif
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<wchar_t>::result
+__codecvt_utf8<wchar_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+#if defined(_LIBCPP_SHORT_WCHAR)
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf8_to_ucs2(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+#else
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf8_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+#endif
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<wchar_t>::result
+__codecvt_utf8<wchar_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8<wchar_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8<wchar_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8<wchar_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8<wchar_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 7;
+    return 4;
+}
+
+// __codecvt_utf8<char16_t>
+
+__codecvt_utf8<char16_t>::result
+__codecvt_utf8<char16_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs2_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<char16_t>::result
+__codecvt_utf8<char16_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf8_to_ucs2(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<char16_t>::result
+__codecvt_utf8<char16_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8<char16_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8<char16_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8<char16_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_ucs2_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8<char16_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 6;
+    return 3;
+}
+
+// __codecvt_utf8<char32_t>
+
+__codecvt_utf8<char32_t>::result
+__codecvt_utf8<char32_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<char32_t>::result
+__codecvt_utf8<char32_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf8_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                            _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8<char32_t>::result
+__codecvt_utf8<char32_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8<char32_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8<char32_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8<char32_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8<char32_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 7;
+    return 4;
+}
+
+// __codecvt_utf16<wchar_t, false>
+
+__codecvt_utf16<wchar_t, false>::result
+__codecvt_utf16<wchar_t, false>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf16be(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<wchar_t, false>::result
+__codecvt_utf16<wchar_t, false>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf16be_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<wchar_t, false>::result
+__codecvt_utf16<wchar_t, false>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<wchar_t, false>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<wchar_t, false>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<wchar_t, false>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16be_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<wchar_t, false>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 6;
+    return 4;
+}
+
+// __codecvt_utf16<wchar_t, true>
+
+__codecvt_utf16<wchar_t, true>::result
+__codecvt_utf16<wchar_t, true>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf16le(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<wchar_t, true>::result
+__codecvt_utf16<wchar_t, true>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf16le_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<wchar_t, true>::result
+__codecvt_utf16<wchar_t, true>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<wchar_t, true>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<wchar_t, true>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<wchar_t, true>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16le_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<wchar_t, true>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 6;
+    return 4;
+}
+
+// __codecvt_utf16<char16_t, false>
+
+__codecvt_utf16<char16_t, false>::result
+__codecvt_utf16<char16_t, false>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs2_to_utf16be(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char16_t, false>::result
+__codecvt_utf16<char16_t, false>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf16be_to_ucs2(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char16_t, false>::result
+__codecvt_utf16<char16_t, false>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<char16_t, false>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<char16_t, false>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<char16_t, false>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16be_to_ucs2_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<char16_t, false>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 4;
+    return 2;
+}
+
+// __codecvt_utf16<char16_t, true>
+
+__codecvt_utf16<char16_t, true>::result
+__codecvt_utf16<char16_t, true>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs2_to_utf16le(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char16_t, true>::result
+__codecvt_utf16<char16_t, true>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf16le_to_ucs2(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char16_t, true>::result
+__codecvt_utf16<char16_t, true>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<char16_t, true>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<char16_t, true>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<char16_t, true>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16le_to_ucs2_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<char16_t, true>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 4;
+    return 2;
+}
+
+// __codecvt_utf16<char32_t, false>
+
+__codecvt_utf16<char32_t, false>::result
+__codecvt_utf16<char32_t, false>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf16be(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char32_t, false>::result
+__codecvt_utf16<char32_t, false>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf16be_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char32_t, false>::result
+__codecvt_utf16<char32_t, false>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<char32_t, false>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<char32_t, false>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<char32_t, false>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16be_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<char32_t, false>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 6;
+    return 4;
+}
+
+// __codecvt_utf16<char32_t, true>
+
+__codecvt_utf16<char32_t, true>::result
+__codecvt_utf16<char32_t, true>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = ucs4_to_utf16le(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char32_t, true>::result
+__codecvt_utf16<char32_t, true>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf16le_to_ucs4(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                               _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf16<char32_t, true>::result
+__codecvt_utf16<char32_t, true>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf16<char32_t, true>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf16<char32_t, true>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf16<char32_t, true>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf16le_to_ucs4_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf16<char32_t, true>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 6;
+    return 4;
+}
+
+// __codecvt_utf8_utf16<wchar_t>
+
+__codecvt_utf8_utf16<wchar_t>::result
+__codecvt_utf8_utf16<wchar_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = utf16_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<wchar_t>::result
+__codecvt_utf8_utf16<wchar_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf8_to_utf16(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<wchar_t>::result
+__codecvt_utf8_utf16<wchar_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8_utf16<wchar_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8_utf16<wchar_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8_utf16<wchar_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_utf16_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8_utf16<wchar_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 7;
+    return 4;
+}
+
+// __codecvt_utf8_utf16<char16_t>
+
+__codecvt_utf8_utf16<char16_t>::result
+__codecvt_utf8_utf16<char16_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint16_t* _frm = reinterpret_cast<const uint16_t*>(frm);
+    const uint16_t* _frm_end = reinterpret_cast<const uint16_t*>(frm_end);
+    const uint16_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = utf16_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<char16_t>::result
+__codecvt_utf8_utf16<char16_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint16_t* _to = reinterpret_cast<uint16_t*>(to);
+    uint16_t* _to_end = reinterpret_cast<uint16_t*>(to_end);
+    uint16_t* _to_nxt = _to;
+    result r = utf8_to_utf16(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<char16_t>::result
+__codecvt_utf8_utf16<char16_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8_utf16<char16_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8_utf16<char16_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8_utf16<char16_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_utf16_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8_utf16<char16_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 7;
+    return 4;
+}
+
+// __codecvt_utf8_utf16<char32_t>
+
+__codecvt_utf8_utf16<char32_t>::result
+__codecvt_utf8_utf16<char32_t>::do_out(state_type&,
+    const intern_type* frm, const intern_type* frm_end, const intern_type*& frm_nxt,
+    extern_type* to, extern_type* to_end, extern_type*& to_nxt) const
+{
+    const uint32_t* _frm = reinterpret_cast<const uint32_t*>(frm);
+    const uint32_t* _frm_end = reinterpret_cast<const uint32_t*>(frm_end);
+    const uint32_t* _frm_nxt = _frm;
+    uint8_t* _to = reinterpret_cast<uint8_t*>(to);
+    uint8_t* _to_end = reinterpret_cast<uint8_t*>(to_end);
+    uint8_t* _to_nxt = _to;
+    result r = utf16_to_utf8(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<char32_t>::result
+__codecvt_utf8_utf16<char32_t>::do_in(state_type&,
+    const extern_type* frm, const extern_type* frm_end, const extern_type*& frm_nxt,
+    intern_type* to, intern_type* to_end, intern_type*& to_nxt) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    const uint8_t* _frm_nxt = _frm;
+    uint32_t* _to = reinterpret_cast<uint32_t*>(to);
+    uint32_t* _to_end = reinterpret_cast<uint32_t*>(to_end);
+    uint32_t* _to_nxt = _to;
+    result r = utf8_to_utf16(_frm, _frm_end, _frm_nxt, _to, _to_end, _to_nxt,
+                             _Maxcode_, _Mode_);
+    frm_nxt = frm + (_frm_nxt - _frm);
+    to_nxt = to + (_to_nxt - _to);
+    return r;
+}
+
+__codecvt_utf8_utf16<char32_t>::result
+__codecvt_utf8_utf16<char32_t>::do_unshift(state_type&,
+    extern_type* to, extern_type*, extern_type*& to_nxt) const
+{
+    to_nxt = to;
+    return noconv;
+}
+
+int
+__codecvt_utf8_utf16<char32_t>::do_encoding() const  _NOEXCEPT
+{
+    return 0;
+}
+
+bool
+__codecvt_utf8_utf16<char32_t>::do_always_noconv() const  _NOEXCEPT
+{
+    return false;
+}
+
+int
+__codecvt_utf8_utf16<char32_t>::do_length(state_type&,
+    const extern_type* frm, const extern_type* frm_end, size_t mx) const
+{
+    const uint8_t* _frm = reinterpret_cast<const uint8_t*>(frm);
+    const uint8_t* _frm_end = reinterpret_cast<const uint8_t*>(frm_end);
+    return utf8_to_utf16_length(_frm, _frm_end, mx, _Maxcode_, _Mode_);
+}
+
+int
+__codecvt_utf8_utf16<char32_t>::do_max_length() const  _NOEXCEPT
+{
+    if (_Mode_ & consume_header)
+        return 7;
+    return 4;
+}
+
+// __narrow_to_utf8<16>
+
+__narrow_to_utf8<16>::~__narrow_to_utf8()
+{
+}
+
+// __narrow_to_utf8<32>
+
+__narrow_to_utf8<32>::~__narrow_to_utf8()
+{
+}
+
+// __widen_from_utf8<16>
+
+__widen_from_utf8<16>::~__widen_from_utf8()
+{
+}
+
+// __widen_from_utf8<32>
+
+__widen_from_utf8<32>::~__widen_from_utf8()
+{
+}
+
+
+static bool checked_string_to_wchar_convert(wchar_t& dest,
+                                            const char* ptr,
+                                            locale_t loc) {
+  if (*ptr == '\0')
+    return false;
+  mbstate_t mb = {};
+  wchar_t out;
+  size_t ret = __libcpp_mbrtowc_l(&out, ptr, strlen(ptr), &mb, loc);
+  if (ret == static_cast<size_t>(-1) || ret == static_cast<size_t>(-2)) {
+    return false;
+  }
+  dest = out;
+  return true;
+}
+
+static bool checked_string_to_char_convert(char& dest,
+                                           const char* ptr,
+                                           locale_t __loc) {
+  if (*ptr == '\0')
+    return false;
+  if (!ptr[1]) {
+    dest = *ptr;
+    return true;
+  }
+  // First convert the MBS into a wide char then attempt to narrow it using
+  // wctob_l.
+  wchar_t wout;
+  if (!checked_string_to_wchar_convert(wout, ptr, __loc))
+    return false;
+  int res;
+  if ((res = __libcpp_wctob_l(wout, __loc)) != char_traits<char>::eof()) {
+    dest = res;
+    return true;
+  }
+  // FIXME: Work around specific multibyte sequences that we can reasonable
+  // translate into a different single byte.
+  switch (wout) {
+  case L'\u202F': // narrow non-breaking space
+  case L'\u00A0': // non-breaking space
+    dest = ' ';
+    return true;
+  default:
+    return false;
+  }
+  _LIBCPP_UNREACHABLE();
+}
+
+
+// numpunct<char> && numpunct<wchar_t>
+
+locale::id numpunct< char  >::id;
+locale::id numpunct<wchar_t>::id;
+
+numpunct<char>::numpunct(size_t refs)
+    : locale::facet(refs),
+      __decimal_point_('.'),
+      __thousands_sep_(',')
+{
+}
+
+numpunct<wchar_t>::numpunct(size_t refs)
+    : locale::facet(refs),
+      __decimal_point_(L'.'),
+      __thousands_sep_(L',')
+{
+}
+
+numpunct<char>::~numpunct()
+{
+}
+
+numpunct<wchar_t>::~numpunct()
+{
+}
+
+ char   numpunct< char  >::do_decimal_point() const {return __decimal_point_;}
+wchar_t numpunct<wchar_t>::do_decimal_point() const {return __decimal_point_;}
+
+ char   numpunct< char  >::do_thousands_sep() const {return __thousands_sep_;}
+wchar_t numpunct<wchar_t>::do_thousands_sep() const {return __thousands_sep_;}
+
+string numpunct< char  >::do_grouping() const {return __grouping_;}
+string numpunct<wchar_t>::do_grouping() const {return __grouping_;}
+
+ string numpunct< char  >::do_truename() const {return "true";}
+wstring numpunct<wchar_t>::do_truename() const {return L"true";}
+
+ string numpunct< char  >::do_falsename() const {return "false";}
+wstring numpunct<wchar_t>::do_falsename() const {return L"false";}
+
+// numpunct_byname<char>
+
+numpunct_byname<char>::numpunct_byname(const char* nm, size_t refs)
+    : numpunct<char>(refs)
+{
+    __init(nm);
+}
+
+numpunct_byname<char>::numpunct_byname(const string& nm, size_t refs)
+    : numpunct<char>(refs)
+{
+    __init(nm.c_str());
+}
+
+numpunct_byname<char>::~numpunct_byname()
+{
+}
+
+void
+numpunct_byname<char>::__init(const char* nm)
+{
+    if (strcmp(nm, "C") != 0)
+    {
+        __libcpp_unique_locale loc(nm);
+        if (!loc)
+            __throw_runtime_error("numpunct_byname<char>::numpunct_byname"
+                                " failed to construct for " + string(nm));
+
+        lconv* lc = __libcpp_localeconv_l(loc.get());
+        checked_string_to_char_convert(__decimal_point_, lc->decimal_point,
+                                       loc.get());
+        checked_string_to_char_convert(__thousands_sep_, lc->thousands_sep,
+                                       loc.get());
+        __grouping_ = lc->grouping;
+        // localization for truename and falsename is not available
+    }
+}
+
+// numpunct_byname<wchar_t>
+
+numpunct_byname<wchar_t>::numpunct_byname(const char* nm, size_t refs)
+    : numpunct<wchar_t>(refs)
+{
+    __init(nm);
+}
+
+numpunct_byname<wchar_t>::numpunct_byname(const string& nm, size_t refs)
+    : numpunct<wchar_t>(refs)
+{
+    __init(nm.c_str());
+}
+
+numpunct_byname<wchar_t>::~numpunct_byname()
+{
+}
+
+void
+numpunct_byname<wchar_t>::__init(const char* nm)
+{
+    if (strcmp(nm, "C") != 0)
+    {
+        __libcpp_unique_locale loc(nm);
+        if (!loc)
+            __throw_runtime_error("numpunct_byname<wchar_t>::numpunct_byname"
+                                " failed to construct for " + string(nm));
+
+        lconv* lc = __libcpp_localeconv_l(loc.get());
+        checked_string_to_wchar_convert(__decimal_point_, lc->decimal_point,
+                                        loc.get());
+        checked_string_to_wchar_convert(__thousands_sep_, lc->thousands_sep,
+                                        loc.get());
+        __grouping_ = lc->grouping;
+        // localization for truename and falsename is not available
+    }
+}
+
+// num_get helpers
+
+int
+__num_get_base::__get_base(ios_base& iob)
+{
+    ios_base::fmtflags __basefield = iob.flags() & ios_base::basefield;
+    if (__basefield == ios_base::oct)
+        return 8;
+    else if (__basefield == ios_base::hex)
+        return 16;
+    else if (__basefield == 0)
+        return 0;
+    return 10;
+}
+
+const char __num_get_base::__src[33] = "0123456789abcdefABCDEFxX+-pPiInN";
+
+void
+__check_grouping(const string& __grouping, unsigned* __g, unsigned* __g_end,
+                 ios_base::iostate& __err)
+{
+//  if the grouping pattern is empty _or_ there are no grouping bits, then do nothing
+//  we always have at least a single entry in [__g, __g_end); the end of the input sequence
+	if (__grouping.size() != 0 && __g_end - __g > 1)
+    {
+        reverse(__g, __g_end);
+        const char* __ig = __grouping.data();
+        const char* __eg = __ig + __grouping.size();
+        for (unsigned* __r = __g; __r < __g_end-1; ++__r)
+        {
+            if (0 < *__ig && *__ig < numeric_limits<char>::max())
+            {
+                if (static_cast<unsigned>(*__ig) != *__r)
+                {
+                    __err = ios_base::failbit;
+                    return;
+                }
+            }
+            if (__eg - __ig > 1)
+                ++__ig;
+        }
+        if (0 < *__ig && *__ig < numeric_limits<char>::max())
+        {
+            if (static_cast<unsigned>(*__ig) < __g_end[-1] || __g_end[-1] == 0)
+                __err = ios_base::failbit;
+        }
+    }
+}
+
+void
+__num_put_base::__format_int(char* __fmtp, const char* __len, bool __signd,
+                             ios_base::fmtflags __flags)
+{
+    if (__flags & ios_base::showpos)
+        *__fmtp++ = '+';
+    if (__flags & ios_base::showbase)
+        *__fmtp++ = '#';
+    while(*__len)
+        *__fmtp++ = *__len++;
+    if ((__flags & ios_base::basefield) == ios_base::oct)
+        *__fmtp = 'o';
+    else if ((__flags & ios_base::basefield) == ios_base::hex)
+    {
+        if (__flags & ios_base::uppercase)
+            *__fmtp = 'X';
+        else
+            *__fmtp = 'x';
+    }
+    else if (__signd)
+        *__fmtp = 'd';
+    else
+        *__fmtp = 'u';
+}
+
+bool
+__num_put_base::__format_float(char* __fmtp, const char* __len,
+                               ios_base::fmtflags __flags)
+{
+    bool specify_precision = true;
+    if (__flags & ios_base::showpos)
+        *__fmtp++ = '+';
+    if (__flags & ios_base::showpoint)
+        *__fmtp++ = '#';
+    ios_base::fmtflags floatfield = __flags & ios_base::floatfield;
+    bool uppercase = (__flags & ios_base::uppercase) != 0;
+    if (floatfield == (ios_base::fixed | ios_base::scientific))
+        specify_precision = false;
+    else
+    {
+        *__fmtp++ = '.';
+        *__fmtp++ = '*';
+    }
+    while(*__len)
+        *__fmtp++ = *__len++;
+    if (floatfield == ios_base::fixed)
+    {
+        if (uppercase)
+            *__fmtp = 'F';
+        else
+            *__fmtp = 'f';
+    }
+    else if (floatfield == ios_base::scientific)
+    {
+        if (uppercase)
+            *__fmtp = 'E';
+        else
+            *__fmtp = 'e';
+    }
+    else if (floatfield == (ios_base::fixed | ios_base::scientific))
+    {
+        if (uppercase)
+            *__fmtp = 'A';
+        else
+            *__fmtp = 'a';
+    }
+    else
+    {
+        if (uppercase)
+            *__fmtp = 'G';
+        else
+            *__fmtp = 'g';
+    }
+    return specify_precision;
+}
+
+char*
+__num_put_base::__identify_padding(char* __nb, char* __ne,
+                                   const ios_base& __iob)
+{
+    switch (__iob.flags() & ios_base::adjustfield)
+    {
+    case ios_base::internal:
+        if (__nb[0] == '-' || __nb[0] == '+')
+            return __nb+1;
+        if (__ne - __nb >= 2 && __nb[0] == '0'
+                            && (__nb[1] == 'x' || __nb[1] == 'X'))
+            return __nb+2;
+        break;
+    case ios_base::left:
+        return __ne;
+    case ios_base::right:
+    default:
+        break;
+    }
+    return __nb;
+}
+
+// time_get
+
+static
+string*
+init_weeks()
+{
+    static string weeks[14];
+    weeks[0]  = "Sunday";
+    weeks[1]  = "Monday";
+    weeks[2]  = "Tuesday";
+    weeks[3]  = "Wednesday";
+    weeks[4]  = "Thursday";
+    weeks[5]  = "Friday";
+    weeks[6]  = "Saturday";
+    weeks[7]  = "Sun";
+    weeks[8]  = "Mon";
+    weeks[9]  = "Tue";
+    weeks[10] = "Wed";
+    weeks[11] = "Thu";
+    weeks[12] = "Fri";
+    weeks[13] = "Sat";
+    return weeks;
+}
+
+static
+wstring*
+init_wweeks()
+{
+    static wstring weeks[14];
+    weeks[0]  = L"Sunday";
+    weeks[1]  = L"Monday";
+    weeks[2]  = L"Tuesday";
+    weeks[3]  = L"Wednesday";
+    weeks[4]  = L"Thursday";
+    weeks[5]  = L"Friday";
+    weeks[6]  = L"Saturday";
+    weeks[7]  = L"Sun";
+    weeks[8]  = L"Mon";
+    weeks[9]  = L"Tue";
+    weeks[10] = L"Wed";
+    weeks[11] = L"Thu";
+    weeks[12] = L"Fri";
+    weeks[13] = L"Sat";
+    return weeks;
+}
+
+template <>
+const string*
+__time_get_c_storage<char>::__weeks() const
+{
+    static const string* weeks = init_weeks();
+    return weeks;
+}
+
+template <>
+const wstring*
+__time_get_c_storage<wchar_t>::__weeks() const
+{
+    static const wstring* weeks = init_wweeks();
+    return weeks;
+}
+
+static
+string*
+init_months()
+{
+    static string months[24];
+    months[0]  = "January";
+    months[1]  = "February";
+    months[2]  = "March";
+    months[3]  = "April";
+    months[4]  = "May";
+    months[5]  = "June";
+    months[6]  = "July";
+    months[7]  = "August";
+    months[8]  = "September";
+    months[9]  = "October";
+    months[10] = "November";
+    months[11] = "December";
+    months[12] = "Jan";
+    months[13] = "Feb";
+    months[14] = "Mar";
+    months[15] = "Apr";
+    months[16] = "May";
+    months[17] = "Jun";
+    months[18] = "Jul";
+    months[19] = "Aug";
+    months[20] = "Sep";
+    months[21] = "Oct";
+    months[22] = "Nov";
+    months[23] = "Dec";
+    return months;
+}
+
+static
+wstring*
+init_wmonths()
+{
+    static wstring months[24];
+    months[0]  = L"January";
+    months[1]  = L"February";
+    months[2]  = L"March";
+    months[3]  = L"April";
+    months[4]  = L"May";
+    months[5]  = L"June";
+    months[6]  = L"July";
+    months[7]  = L"August";
+    months[8]  = L"September";
+    months[9]  = L"October";
+    months[10] = L"November";
+    months[11] = L"December";
+    months[12] = L"Jan";
+    months[13] = L"Feb";
+    months[14] = L"Mar";
+    months[15] = L"Apr";
+    months[16] = L"May";
+    months[17] = L"Jun";
+    months[18] = L"Jul";
+    months[19] = L"Aug";
+    months[20] = L"Sep";
+    months[21] = L"Oct";
+    months[22] = L"Nov";
+    months[23] = L"Dec";
+    return months;
+}
+
+template <>
+const string*
+__time_get_c_storage<char>::__months() const
+{
+    static const string* months = init_months();
+    return months;
+}
+
+template <>
+const wstring*
+__time_get_c_storage<wchar_t>::__months() const
+{
+    static const wstring* months = init_wmonths();
+    return months;
+}
+
+static
+string*
+init_am_pm()
+{
+    static string am_pm[2];
+    am_pm[0]  = "AM";
+    am_pm[1]  = "PM";
+    return am_pm;
+}
+
+static
+wstring*
+init_wam_pm()
+{
+    static wstring am_pm[2];
+    am_pm[0]  = L"AM";
+    am_pm[1]  = L"PM";
+    return am_pm;
+}
+
+template <>
+const string*
+__time_get_c_storage<char>::__am_pm() const
+{
+    static const string* am_pm = init_am_pm();
+    return am_pm;
+}
+
+template <>
+const wstring*
+__time_get_c_storage<wchar_t>::__am_pm() const
+{
+    static const wstring* am_pm = init_wam_pm();
+    return am_pm;
+}
+
+template <>
+const string&
+__time_get_c_storage<char>::__x() const
+{
+    static string s("%m/%d/%y");
+    return s;
+}
+
+template <>
+const wstring&
+__time_get_c_storage<wchar_t>::__x() const
+{
+    static wstring s(L"%m/%d/%y");
+    return s;
+}
+
+template <>
+const string&
+__time_get_c_storage<char>::__X() const
+{
+    static string s("%H:%M:%S");
+    return s;
+}
+
+template <>
+const wstring&
+__time_get_c_storage<wchar_t>::__X() const
+{
+    static wstring s(L"%H:%M:%S");
+    return s;
+}
+
+template <>
+const string&
+__time_get_c_storage<char>::__c() const
+{
+    static string s("%a %b %d %H:%M:%S %Y");
+    return s;
+}
+
+template <>
+const wstring&
+__time_get_c_storage<wchar_t>::__c() const
+{
+    static wstring s(L"%a %b %d %H:%M:%S %Y");
+    return s;
+}
+
+template <>
+const string&
+__time_get_c_storage<char>::__r() const
+{
+    static string s("%I:%M:%S %p");
+    return s;
+}
+
+template <>
+const wstring&
+__time_get_c_storage<wchar_t>::__r() const
+{
+    static wstring s(L"%I:%M:%S %p");
+    return s;
+}
+
+// time_get_byname
+
+__time_get::__time_get(const char* nm)
+    : __loc_(newlocale(LC_ALL_MASK, nm, 0))
+{
+    if (__loc_ == 0)
+        __throw_runtime_error("time_get_byname"
+                            " failed to construct for " + string(nm));
+}
+
+__time_get::__time_get(const string& nm)
+    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), 0))
+{
+    if (__loc_ == 0)
+        __throw_runtime_error("time_get_byname"
+                            " failed to construct for " + nm);
+}
+
+__time_get::~__time_get()
+{
+    freelocale(__loc_);
+}
+#if defined(__clang__)
+#pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#endif
+#if defined(__GNUG__)
+#pragma GCC   diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+template <>
+string
+__time_get_storage<char>::__analyze(char fmt, const ctype<char>& ct)
+{
+    tm t = {0};
+    t.tm_sec = 59;
+    t.tm_min = 55;
+    t.tm_hour = 23;
+    t.tm_mday = 31;
+    t.tm_mon = 11;
+    t.tm_year = 161;
+    t.tm_wday = 6;
+    t.tm_yday = 364;
+    t.tm_isdst = -1;
+    char buf[100];
+    char f[3] = {0};
+    f[0] = '%';
+    f[1] = fmt;
+    size_t n = strftime_l(buf, countof(buf), f, &t, __loc_);
+    char* bb = buf;
+    char* be = buf + n;
+    string result;
+    while (bb != be)
+    {
+        if (ct.is(ctype_base::space, *bb))
+        {
+            result.push_back(' ');
+            for (++bb; bb != be && ct.is(ctype_base::space, *bb); ++bb)
+                ;
+            continue;
+        }
+        char* w = bb;
+        ios_base::iostate err = ios_base::goodbit;
+        ptrdiff_t i = __scan_keyword(w, be, this->__weeks_, this->__weeks_+14,
+                               ct, err, false)
+                               - this->__weeks_;
+        if (i < 14)
+        {
+            result.push_back('%');
+            if (i < 7)
+                result.push_back('A');
+            else
+                result.push_back('a');
+            bb = w;
+            continue;
+        }
+        w = bb;
+        i = __scan_keyword(w, be, this->__months_, this->__months_+24,
+                           ct, err, false)
+                           - this->__months_;
+        if (i < 24)
+        {
+            result.push_back('%');
+            if (i < 12)
+                result.push_back('B');
+            else
+                result.push_back('b');
+            if (fmt == 'x' && ct.is(ctype_base::digit, this->__months_[i][0]))
+                result.back() = 'm';
+            bb = w;
+            continue;
+        }
+        if (this->__am_pm_[0].size() + this->__am_pm_[1].size() > 0)
+        {
+            w = bb;
+            i = __scan_keyword(w, be, this->__am_pm_, this->__am_pm_+2,
+                               ct, err, false) - this->__am_pm_;
+            if (i < 2)
+            {
+                result.push_back('%');
+                result.push_back('p');
+                bb = w;
+                continue;
+            }
+        }
+        w = bb;
+        if (ct.is(ctype_base::digit, *bb))
+        {
+            switch(__get_up_to_n_digits(bb, be, err, ct, 4))
+            {
+            case 6:
+                result.push_back('%');
+                result.push_back('w');
+                break;
+            case 7:
+                result.push_back('%');
+                result.push_back('u');
+                break;
+            case 11:
+                result.push_back('%');
+                result.push_back('I');
+                break;
+            case 12:
+                result.push_back('%');
+                result.push_back('m');
+                break;
+            case 23:
+                result.push_back('%');
+                result.push_back('H');
+                break;
+            case 31:
+                result.push_back('%');
+                result.push_back('d');
+                break;
+            case 55:
+                result.push_back('%');
+                result.push_back('M');
+                break;
+            case 59:
+                result.push_back('%');
+                result.push_back('S');
+                break;
+            case 61:
+                result.push_back('%');
+                result.push_back('y');
+                break;
+            case 364:
+                result.push_back('%');
+                result.push_back('j');
+                break;
+            case 2061:
+                result.push_back('%');
+                result.push_back('Y');
+                break;
+            default:
+                for (; w != bb; ++w)
+                    result.push_back(*w);
+                break;
+            }
+            continue;
+        }
+        if (*bb == '%')
+        {
+            result.push_back('%');
+            result.push_back('%');
+            ++bb;
+            continue;
+        }
+        result.push_back(*bb);
+        ++bb;
+    }
+    return result;
+}
+
+#if defined(__clang__)
+#pragma clang diagnostic ignored "-Wmissing-braces"
+#endif
+
+template <>
+wstring
+__time_get_storage<wchar_t>::__analyze(char fmt, const ctype<wchar_t>& ct)
+{
+    tm t = {0};
+    t.tm_sec = 59;
+    t.tm_min = 55;
+    t.tm_hour = 23;
+    t.tm_mday = 31;
+    t.tm_mon = 11;
+    t.tm_year = 161;
+    t.tm_wday = 6;
+    t.tm_yday = 364;
+    t.tm_isdst = -1;
+    char buf[100];
+    char f[3] = {0};
+    f[0] = '%';
+    f[1] = fmt;
+    strftime_l(buf, countof(buf), f, &t, __loc_);
+    wchar_t wbuf[100];
+    wchar_t* wbb = wbuf;
+    mbstate_t mb = {0};
+    const char* bb = buf;
+    size_t j = __libcpp_mbsrtowcs_l( wbb, &bb, countof(wbuf), &mb, __loc_);
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    wchar_t* wbe = wbb + j;
+    wstring result;
+    while (wbb != wbe)
+    {
+        if (ct.is(ctype_base::space, *wbb))
+        {
+            result.push_back(L' ');
+            for (++wbb; wbb != wbe && ct.is(ctype_base::space, *wbb); ++wbb)
+                ;
+            continue;
+        }
+        wchar_t* w = wbb;
+        ios_base::iostate err = ios_base::goodbit;
+        ptrdiff_t i = __scan_keyword(w, wbe, this->__weeks_, this->__weeks_+14,
+                               ct, err, false)
+                               - this->__weeks_;
+        if (i < 14)
+        {
+            result.push_back(L'%');
+            if (i < 7)
+                result.push_back(L'A');
+            else
+                result.push_back(L'a');
+            wbb = w;
+            continue;
+        }
+        w = wbb;
+        i = __scan_keyword(w, wbe, this->__months_, this->__months_+24,
+                           ct, err, false)
+                           - this->__months_;
+        if (i < 24)
+        {
+            result.push_back(L'%');
+            if (i < 12)
+                result.push_back(L'B');
+            else
+                result.push_back(L'b');
+            if (fmt == 'x' && ct.is(ctype_base::digit, this->__months_[i][0]))
+                result.back() = L'm';
+            wbb = w;
+            continue;
+        }
+        if (this->__am_pm_[0].size() + this->__am_pm_[1].size() > 0)
+        {
+            w = wbb;
+            i = __scan_keyword(w, wbe, this->__am_pm_, this->__am_pm_+2,
+                               ct, err, false) - this->__am_pm_;
+            if (i < 2)
+            {
+                result.push_back(L'%');
+                result.push_back(L'p');
+                wbb = w;
+                continue;
+            }
+        }
+        w = wbb;
+        if (ct.is(ctype_base::digit, *wbb))
+        {
+            switch(__get_up_to_n_digits(wbb, wbe, err, ct, 4))
+            {
+            case 6:
+                result.push_back(L'%');
+                result.push_back(L'w');
+                break;
+            case 7:
+                result.push_back(L'%');
+                result.push_back(L'u');
+                break;
+            case 11:
+                result.push_back(L'%');
+                result.push_back(L'I');
+                break;
+            case 12:
+                result.push_back(L'%');
+                result.push_back(L'm');
+                break;
+            case 23:
+                result.push_back(L'%');
+                result.push_back(L'H');
+                break;
+            case 31:
+                result.push_back(L'%');
+                result.push_back(L'd');
+                break;
+            case 55:
+                result.push_back(L'%');
+                result.push_back(L'M');
+                break;
+            case 59:
+                result.push_back(L'%');
+                result.push_back(L'S');
+                break;
+            case 61:
+                result.push_back(L'%');
+                result.push_back(L'y');
+                break;
+            case 364:
+                result.push_back(L'%');
+                result.push_back(L'j');
+                break;
+            case 2061:
+                result.push_back(L'%');
+                result.push_back(L'Y');
+                break;
+            default:
+                for (; w != wbb; ++w)
+                    result.push_back(*w);
+                break;
+            }
+            continue;
+        }
+        if (ct.narrow(*wbb, 0) == '%')
+        {
+            result.push_back(L'%');
+            result.push_back(L'%');
+            ++wbb;
+            continue;
+        }
+        result.push_back(*wbb);
+        ++wbb;
+    }
+    return result;
+}
+
+template <>
+void
+__time_get_storage<char>::init(const ctype<char>& ct)
+{
+    tm t = {0};
+    char buf[100];
+    // __weeks_
+    for (int i = 0; i < 7; ++i)
+    {
+        t.tm_wday = i;
+        strftime_l(buf, countof(buf), "%A", &t, __loc_);
+        __weeks_[i] = buf;
+        strftime_l(buf, countof(buf), "%a", &t, __loc_);
+        __weeks_[i+7] = buf;
+    }
+    // __months_
+    for (int i = 0; i < 12; ++i)
+    {
+        t.tm_mon = i;
+        strftime_l(buf, countof(buf), "%B", &t, __loc_);
+        __months_[i] = buf;
+        strftime_l(buf, countof(buf), "%b", &t, __loc_);
+        __months_[i+12] = buf;
+    }
+    // __am_pm_
+    t.tm_hour = 1;
+    strftime_l(buf, countof(buf), "%p", &t, __loc_);
+    __am_pm_[0] = buf;
+    t.tm_hour = 13;
+    strftime_l(buf, countof(buf), "%p", &t, __loc_);
+    __am_pm_[1] = buf;
+    __c_ = __analyze('c', ct);
+    __r_ = __analyze('r', ct);
+    __x_ = __analyze('x', ct);
+    __X_ = __analyze('X', ct);
+}
+
+template <>
+void
+__time_get_storage<wchar_t>::init(const ctype<wchar_t>& ct)
+{
+    tm t = {0};
+    char buf[100];
+    wchar_t wbuf[100];
+    wchar_t* wbe;
+    mbstate_t mb = {0};
+    // __weeks_
+    for (int i = 0; i < 7; ++i)
+    {
+        t.tm_wday = i;
+        strftime_l(buf, countof(buf), "%A", &t, __loc_);
+        mb = mbstate_t();
+        const char* bb = buf;
+        size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __weeks_[i].assign(wbuf, wbe);
+        strftime_l(buf, countof(buf), "%a", &t, __loc_);
+        mb = mbstate_t();
+        bb = buf;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __weeks_[i+7].assign(wbuf, wbe);
+    }
+    // __months_
+    for (int i = 0; i < 12; ++i)
+    {
+        t.tm_mon = i;
+        strftime_l(buf, countof(buf), "%B", &t, __loc_);
+        mb = mbstate_t();
+        const char* bb = buf;
+        size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __months_[i].assign(wbuf, wbe);
+        strftime_l(buf, countof(buf), "%b", &t, __loc_);
+        mb = mbstate_t();
+        bb = buf;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __months_[i+12].assign(wbuf, wbe);
+    }
+    // __am_pm_
+    t.tm_hour = 1;
+    strftime_l(buf, countof(buf), "%p", &t, __loc_);
+    mb = mbstate_t();
+    const char* bb = buf;
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    wbe = wbuf + j;
+    __am_pm_[0].assign(wbuf, wbe);
+    t.tm_hour = 13;
+    strftime_l(buf, countof(buf), "%p", &t, __loc_);
+    mb = mbstate_t();
+    bb = buf;
+    j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    wbe = wbuf + j;
+    __am_pm_[1].assign(wbuf, wbe);
+    __c_ = __analyze('c', ct);
+    __r_ = __analyze('r', ct);
+    __x_ = __analyze('x', ct);
+    __X_ = __analyze('X', ct);
+}
+
+template <class CharT>
+struct _LIBCPP_HIDDEN __time_get_temp
+    : public ctype_byname<CharT>
+{
+    explicit __time_get_temp(const char* nm)
+        : ctype_byname<CharT>(nm, 1) {}
+    explicit __time_get_temp(const string& nm)
+        : ctype_byname<CharT>(nm, 1) {}
+};
+
+template <>
+__time_get_storage<char>::__time_get_storage(const char* __nm)
+    : __time_get(__nm)
+{
+    const __time_get_temp<char> ct(__nm);
+    init(ct);
+}
+
+template <>
+__time_get_storage<char>::__time_get_storage(const string& __nm)
+    : __time_get(__nm)
+{
+    const __time_get_temp<char> ct(__nm);
+    init(ct);
+}
+
+template <>
+__time_get_storage<wchar_t>::__time_get_storage(const char* __nm)
+    : __time_get(__nm)
+{
+    const __time_get_temp<wchar_t> ct(__nm);
+    init(ct);
+}
+
+template <>
+__time_get_storage<wchar_t>::__time_get_storage(const string& __nm)
+    : __time_get(__nm)
+{
+    const __time_get_temp<wchar_t> ct(__nm);
+    init(ct);
+}
+
+template <>
+time_base::dateorder
+__time_get_storage<char>::__do_date_order() const
+{
+    unsigned i;
+    for (i = 0; i < __x_.size(); ++i)
+        if (__x_[i] == '%')
+            break;
+    ++i;
+    switch (__x_[i])
+    {
+    case 'y':
+    case 'Y':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == '%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        switch (__x_[i])
+        {
+        case 'm':
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == '%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == 'd')
+                return time_base::ymd;
+            break;
+        case 'd':
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == '%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == 'm')
+                return time_base::ydm;
+            break;
+        }
+        break;
+    case 'm':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == '%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        if (__x_[i] == 'd')
+        {
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == '%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == 'y' || __x_[i] == 'Y')
+                return time_base::mdy;
+            break;
+        }
+        break;
+    case 'd':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == '%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        if (__x_[i] == 'm')
+        {
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == '%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == 'y' || __x_[i] == 'Y')
+                return time_base::dmy;
+            break;
+        }
+        break;
+    }
+    return time_base::no_order;
+}
+
+template <>
+time_base::dateorder
+__time_get_storage<wchar_t>::__do_date_order() const
+{
+    unsigned i;
+    for (i = 0; i < __x_.size(); ++i)
+        if (__x_[i] == L'%')
+            break;
+    ++i;
+    switch (__x_[i])
+    {
+    case L'y':
+    case L'Y':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == L'%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        switch (__x_[i])
+        {
+        case L'm':
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == L'%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == L'd')
+                return time_base::ymd;
+            break;
+        case L'd':
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == L'%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == L'm')
+                return time_base::ydm;
+            break;
+        }
+        break;
+    case L'm':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == L'%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        if (__x_[i] == L'd')
+        {
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == L'%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == L'y' || __x_[i] == L'Y')
+                return time_base::mdy;
+            break;
+        }
+        break;
+    case L'd':
+        for (++i; i < __x_.size(); ++i)
+            if (__x_[i] == L'%')
+                break;
+        if (i == __x_.size())
+            break;
+        ++i;
+        if (__x_[i] == L'm')
+        {
+            for (++i; i < __x_.size(); ++i)
+                if (__x_[i] == L'%')
+                    break;
+            if (i == __x_.size())
+                break;
+            ++i;
+            if (__x_[i] == L'y' || __x_[i] == L'Y')
+                return time_base::dmy;
+            break;
+        }
+        break;
+    }
+    return time_base::no_order;
+}
+
+// time_put
+
+__time_put::__time_put(const char* nm)
+    : __loc_(newlocale(LC_ALL_MASK, nm, 0))
+{
+    if (__loc_ == 0)
+        __throw_runtime_error("time_put_byname"
+                            " failed to construct for " + string(nm));
+}
+
+__time_put::__time_put(const string& nm)
+    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), 0))
+{
+    if (__loc_ == 0)
+        __throw_runtime_error("time_put_byname"
+                            " failed to construct for " + nm);
+}
+
+__time_put::~__time_put()
+{
+    if (__loc_ != _LIBCPP_GET_C_LOCALE)
+        freelocale(__loc_);
+}
+
+void
+__time_put::__do_put(char* __nb, char*& __ne, const tm* __tm,
+                     char __fmt, char __mod) const
+{
+    char fmt[] = {'%', __fmt, __mod, 0};
+    if (__mod != 0)
+        swap(fmt[1], fmt[2]);
+    size_t n = strftime_l(__nb, countof(__nb, __ne), fmt, __tm, __loc_);
+    __ne = __nb + n;
+}
+
+void
+__time_put::__do_put(wchar_t* __wb, wchar_t*& __we, const tm* __tm,
+                     char __fmt, char __mod) const
+{
+    char __nar[100];
+    char* __ne = __nar + 100;
+    __do_put(__nar, __ne, __tm, __fmt, __mod);
+    mbstate_t mb = {0};
+    const char* __nb = __nar;
+    size_t j = __libcpp_mbsrtowcs_l(__wb, &__nb, countof(__wb, __we), &mb, __loc_);
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    __we = __wb + j;
+}
+
+// moneypunct_byname
+
+template <class charT>
+static
+void
+__init_pat(money_base::pattern& pat, basic_string<charT>& __curr_symbol_,
+           bool intl, char cs_precedes, char sep_by_space, char sign_posn,
+           charT space_char)
+{
+    const char sign = static_cast<char>(money_base::sign);
+    const char space = static_cast<char>(money_base::space);
+    const char none = static_cast<char>(money_base::none);
+    const char symbol = static_cast<char>(money_base::symbol);
+    const char value = static_cast<char>(money_base::value);
+    const bool symbol_contains_sep = intl && __curr_symbol_.size() == 4;
+
+    // Comments on case branches reflect 'C11 7.11.2.1 The localeconv
+    // function'. "Space between sign and symbol or value" means that
+    // if the sign is adjacent to the symbol, there's a space between
+    // them, and otherwise there's a space between the sign and value.
+    //
+    // C11's localeconv specifies that the fourth character of an
+    // international curr_symbol is used to separate the sign and
+    // value when sep_by_space says to do so. C++ can't represent
+    // that, so we just use a space.  When sep_by_space says to
+    // separate the symbol and value-or-sign with a space, we rearrange the
+    // curr_symbol to put its spacing character on the correct side of
+    // the symbol.
+    //
+    // We also need to avoid adding an extra space between the sign
+    // and value when the currency symbol is suppressed (by not
+    // setting showbase).  We match glibc's strfmon by interpreting
+    // sep_by_space==1 as "omit the space when the currency symbol is
+    // absent".
+    //
+    // Users who want to get this right should use ICU instead.
+
+    switch (cs_precedes)
+    {
+    case 0:  // value before curr_symbol
+        if (symbol_contains_sep) {
+            // Move the separator to before the symbol, to place it
+            // between the value and symbol.
+            rotate(__curr_symbol_.begin(), __curr_symbol_.begin() + 3,
+                   __curr_symbol_.end());
+        }
+        switch (sign_posn)
+        {
+        case 0:  // Parentheses surround the quantity and currency symbol.
+            pat.field[0] = sign;
+            pat.field[1] = value;
+            pat.field[2] = none;  // Any space appears in the symbol.
+            pat.field[3] = symbol;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                // This case may have changed between C99 and C11;
+                // assume the currency symbol matches the intention.
+            case 2:  // Space between sign and currency or value.
+                // The "sign" is two parentheses, so no space here either.
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 1:  // The sign string precedes the quantity and currency symbol.
+            pat.field[0] = sign;
+            pat.field[3] = symbol;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = value;
+                pat.field[2] = none;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = value;
+                pat.field[2] = none;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = space;
+                pat.field[2] = value;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // has already appeared after the sign.
+                    __curr_symbol_.erase(__curr_symbol_.begin());
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 2:  // The sign string succeeds the quantity and currency symbol.
+            pat.field[0] = value;
+            pat.field[3] = sign;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = none;
+                pat.field[2] = symbol;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[1]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                pat.field[1] = none;
+                pat.field[2] = symbol;
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = symbol;
+                pat.field[2] = space;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // should not be removed if showbase is absent.
+                    __curr_symbol_.erase(__curr_symbol_.begin());
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 3:  // The sign string immediately precedes the currency symbol.
+            pat.field[0] = value;
+            pat.field[3] = symbol;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = none;
+                pat.field[2] = sign;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = space;
+                pat.field[2] = sign;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // has already appeared before the sign.
+                    __curr_symbol_.erase(__curr_symbol_.begin());
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = sign;
+                pat.field[2] = none;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 4:  // The sign string immediately succeeds the currency symbol.
+            pat.field[0] = value;
+            pat.field[3] = sign;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = none;
+                pat.field[2] = symbol;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = none;
+                pat.field[2] = symbol;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[1]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = symbol;
+                pat.field[2] = space;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // should not disappear when showbase is absent.
+                    __curr_symbol_.erase(__curr_symbol_.begin());
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        default:
+            break;
+        }
+        break;
+    case 1:  // curr_symbol before value
+        switch (sign_posn)
+        {
+        case 0:  // Parentheses surround the quantity and currency symbol.
+            pat.field[0] = sign;
+            pat.field[1] = symbol;
+            pat.field[2] = none;  // Any space appears in the symbol.
+            pat.field[3] = value;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                // This case may have changed between C99 and C11;
+                // assume the currency symbol matches the intention.
+            case 2:  // Space between sign and currency or value.
+                // The "sign" is two parentheses, so no space here either.
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.insert(0, 1, space_char);
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 1:  // The sign string precedes the quantity and currency symbol.
+            pat.field[0] = sign;
+            pat.field[3] = value;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = symbol;
+                pat.field[2] = none;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = symbol;
+                pat.field[2] = none;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.push_back(space_char);
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = space;
+                pat.field[2] = symbol;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // has already appeared after the sign.
+                    __curr_symbol_.pop_back();
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 2:  // The sign string succeeds the quantity and currency symbol.
+            pat.field[0] = symbol;
+            pat.field[3] = sign;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = none;
+                pat.field[2] = value;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = none;
+                pat.field[2] = value;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[1]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.push_back(space_char);
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = value;
+                pat.field[2] = space;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // will appear before the sign.
+                    __curr_symbol_.pop_back();
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 3:  // The sign string immediately precedes the currency symbol.
+            pat.field[0] = sign;
+            pat.field[3] = value;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = symbol;
+                pat.field[2] = none;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = symbol;
+                pat.field[2] = none;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[2]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.push_back(space_char);
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = space;
+                pat.field[2] = symbol;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // has already appeared after the sign.
+                    __curr_symbol_.pop_back();
+                }
+                return;
+            default:
+                break;
+            }
+            break;
+        case 4:  // The sign string immediately succeeds the currency symbol.
+            pat.field[0] = symbol;
+            pat.field[3] = value;
+            switch (sep_by_space)
+            {
+            case 0:  // No space separates the currency symbol and value.
+                pat.field[1] = sign;
+                pat.field[2] = none;
+                return;
+            case 1:  // Space between currency-and-sign or currency and value.
+                pat.field[1] = sign;
+                pat.field[2] = space;
+                if (symbol_contains_sep) {
+                    // Remove the separator from the symbol, since it
+                    // should not disappear when showbase is absent.
+                    __curr_symbol_.pop_back();
+                }
+                return;
+            case 2:  // Space between sign and currency or value.
+                pat.field[1] = none;
+                pat.field[2] = sign;
+                if (!symbol_contains_sep) {
+                    // We insert the space into the symbol instead of
+                    // setting pat.field[1]=space so that when
+                    // showbase is not set, the space goes away too.
+                    __curr_symbol_.push_back(space_char);
+                }
+                return;
+           default:
+                break;
+            }
+            break;
+        default:
+            break;
+        }
+        break;
+    default:
+        break;
+    }
+    pat.field[0] = symbol;
+    pat.field[1] = sign;
+    pat.field[2] = none;
+    pat.field[3] = value;
+}
+
+template<>
+void
+moneypunct_byname<char, false>::init(const char* nm)
+{
+    typedef moneypunct<char, false> base;
+    __libcpp_unique_locale loc(nm);
+    if (!loc)
+        __throw_runtime_error("moneypunct_byname"
+                            " failed to construct for " + string(nm));
+
+    lconv* lc = __libcpp_localeconv_l(loc.get());
+    if (!checked_string_to_char_convert(__decimal_point_,
+                                        lc->mon_decimal_point,
+                                        loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_char_convert(__thousands_sep_,
+                                        lc->mon_thousands_sep,
+                                        loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
+
+    __grouping_ = lc->mon_grouping;
+    __curr_symbol_ = lc->currency_symbol;
+    if (lc->frac_digits != CHAR_MAX)
+        __frac_digits_ = lc->frac_digits;
+    else
+        __frac_digits_ = base::do_frac_digits();
+    if (lc->p_sign_posn == 0)
+        __positive_sign_ = "()";
+    else
+        __positive_sign_ = lc->positive_sign;
+    if (lc->n_sign_posn == 0)
+        __negative_sign_ = "()";
+    else
+        __negative_sign_ = lc->negative_sign;
+    // Assume the positive and negative formats will want spaces in
+    // the same places in curr_symbol since there's no way to
+    // represent anything else.
+    string_type __dummy_curr_symbol = __curr_symbol_;
+    __init_pat(__pos_format_, __dummy_curr_symbol, false,
+               lc->p_cs_precedes, lc->p_sep_by_space, lc->p_sign_posn, ' ');
+    __init_pat(__neg_format_, __curr_symbol_, false,
+               lc->n_cs_precedes, lc->n_sep_by_space, lc->n_sign_posn, ' ');
+}
+
+template<>
+void
+moneypunct_byname<char, true>::init(const char* nm)
+{
+    typedef moneypunct<char, true> base;
+    __libcpp_unique_locale loc(nm);
+    if (!loc)
+        __throw_runtime_error("moneypunct_byname"
+                            " failed to construct for " + string(nm));
+
+    lconv* lc = __libcpp_localeconv_l(loc.get());
+    if (!checked_string_to_char_convert(__decimal_point_,
+                                        lc->mon_decimal_point,
+                                        loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_char_convert(__thousands_sep_,
+                                        lc->mon_thousands_sep,
+                                        loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
+    __grouping_ = lc->mon_grouping;
+    __curr_symbol_ = lc->int_curr_symbol;
+    if (lc->int_frac_digits != CHAR_MAX)
+        __frac_digits_ = lc->int_frac_digits;
+    else
+        __frac_digits_ = base::do_frac_digits();
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    if (lc->p_sign_posn == 0)
+#else // _LIBCPP_MSVCRT
+    if (lc->int_p_sign_posn == 0)
+#endif // !_LIBCPP_MSVCRT
+        __positive_sign_ = "()";
+    else
+        __positive_sign_ = lc->positive_sign;
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    if(lc->n_sign_posn == 0)
+#else // _LIBCPP_MSVCRT
+    if (lc->int_n_sign_posn == 0)
+#endif // !_LIBCPP_MSVCRT
+        __negative_sign_ = "()";
+    else
+        __negative_sign_ = lc->negative_sign;
+    // Assume the positive and negative formats will want spaces in
+    // the same places in curr_symbol since there's no way to
+    // represent anything else.
+    string_type __dummy_curr_symbol = __curr_symbol_;
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    __init_pat(__pos_format_, __dummy_curr_symbol, true,
+               lc->p_cs_precedes, lc->p_sep_by_space, lc->p_sign_posn, ' ');
+    __init_pat(__neg_format_, __curr_symbol_, true,
+               lc->n_cs_precedes, lc->n_sep_by_space, lc->n_sign_posn, ' ');
+#else // _LIBCPP_MSVCRT
+    __init_pat(__pos_format_, __dummy_curr_symbol, true,
+               lc->int_p_cs_precedes, lc->int_p_sep_by_space,
+               lc->int_p_sign_posn, ' ');
+    __init_pat(__neg_format_, __curr_symbol_, true,
+               lc->int_n_cs_precedes, lc->int_n_sep_by_space,
+               lc->int_n_sign_posn, ' ');
+#endif // !_LIBCPP_MSVCRT
+}
+
+template<>
+void
+moneypunct_byname<wchar_t, false>::init(const char* nm)
+{
+    typedef moneypunct<wchar_t, false> base;
+    __libcpp_unique_locale loc(nm);
+    if (!loc)
+        __throw_runtime_error("moneypunct_byname"
+                            " failed to construct for " + string(nm));
+    lconv* lc = __libcpp_localeconv_l(loc.get());
+    if (!checked_string_to_wchar_convert(__decimal_point_,
+                                         lc->mon_decimal_point,
+                                         loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_wchar_convert(__thousands_sep_,
+                                         lc->mon_thousands_sep,
+                                         loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
+    __grouping_ = lc->mon_grouping;
+    wchar_t wbuf[100];
+    mbstate_t mb = {0};
+    const char* bb = lc->currency_symbol;
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    wchar_t* wbe = wbuf + j;
+    __curr_symbol_.assign(wbuf, wbe);
+    if (lc->frac_digits != CHAR_MAX)
+        __frac_digits_ = lc->frac_digits;
+    else
+        __frac_digits_ = base::do_frac_digits();
+    if (lc->p_sign_posn == 0)
+        __positive_sign_ = L"()";
+    else
+    {
+        mb = mbstate_t();
+        bb = lc->positive_sign;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __positive_sign_.assign(wbuf, wbe);
+    }
+    if (lc->n_sign_posn == 0)
+        __negative_sign_ = L"()";
+    else
+    {
+        mb = mbstate_t();
+        bb = lc->negative_sign;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __negative_sign_.assign(wbuf, wbe);
+    }
+    // Assume the positive and negative formats will want spaces in
+    // the same places in curr_symbol since there's no way to
+    // represent anything else.
+    string_type __dummy_curr_symbol = __curr_symbol_;
+    __init_pat(__pos_format_, __dummy_curr_symbol, false,
+               lc->p_cs_precedes, lc->p_sep_by_space, lc->p_sign_posn, L' ');
+    __init_pat(__neg_format_, __curr_symbol_, false,
+               lc->n_cs_precedes, lc->n_sep_by_space, lc->n_sign_posn, L' ');
+}
+
+template<>
+void
+moneypunct_byname<wchar_t, true>::init(const char* nm)
+{
+    typedef moneypunct<wchar_t, true> base;
+    __libcpp_unique_locale loc(nm);
+    if (!loc)
+        __throw_runtime_error("moneypunct_byname"
+                            " failed to construct for " + string(nm));
+
+    lconv* lc = __libcpp_localeconv_l(loc.get());
+    if (!checked_string_to_wchar_convert(__decimal_point_,
+                                         lc->mon_decimal_point,
+                                         loc.get()))
+      __decimal_point_ = base::do_decimal_point();
+    if (!checked_string_to_wchar_convert(__thousands_sep_,
+                                         lc->mon_thousands_sep,
+                                         loc.get()))
+      __thousands_sep_ = base::do_thousands_sep();
+    __grouping_ = lc->mon_grouping;
+    wchar_t wbuf[100];
+    mbstate_t mb = {0};
+    const char* bb = lc->int_curr_symbol;
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+    if (j == size_t(-1))
+        __throw_runtime_error("locale not supported");
+    wchar_t* wbe = wbuf + j;
+    __curr_symbol_.assign(wbuf, wbe);
+    if (lc->int_frac_digits != CHAR_MAX)
+        __frac_digits_ = lc->int_frac_digits;
+    else
+        __frac_digits_ = base::do_frac_digits();
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    if (lc->p_sign_posn == 0)
+#else // _LIBCPP_MSVCRT
+    if (lc->int_p_sign_posn == 0)
+#endif // !_LIBCPP_MSVCRT
+        __positive_sign_ = L"()";
+    else
+    {
+        mb = mbstate_t();
+        bb = lc->positive_sign;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __positive_sign_.assign(wbuf, wbe);
+    }
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    if (lc->n_sign_posn == 0)
+#else // _LIBCPP_MSVCRT
+    if (lc->int_n_sign_posn == 0)
+#endif // !_LIBCPP_MSVCRT
+        __negative_sign_ = L"()";
+    else
+    {
+        mb = mbstate_t();
+        bb = lc->negative_sign;
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
+        if (j == size_t(-1))
+            __throw_runtime_error("locale not supported");
+        wbe = wbuf + j;
+        __negative_sign_.assign(wbuf, wbe);
+    }
+    // Assume the positive and negative formats will want spaces in
+    // the same places in curr_symbol since there's no way to
+    // represent anything else.
+    string_type __dummy_curr_symbol = __curr_symbol_;
+#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
+    __init_pat(__pos_format_, __dummy_curr_symbol, true,
+               lc->p_cs_precedes, lc->p_sep_by_space, lc->p_sign_posn, L' ');
+    __init_pat(__neg_format_, __curr_symbol_, true,
+               lc->n_cs_precedes, lc->n_sep_by_space, lc->n_sign_posn, L' ');
+#else // _LIBCPP_MSVCRT
+    __init_pat(__pos_format_, __dummy_curr_symbol, true,
+               lc->int_p_cs_precedes, lc->int_p_sep_by_space,
+               lc->int_p_sign_posn, L' ');
+    __init_pat(__neg_format_, __curr_symbol_, true,
+               lc->int_n_cs_precedes, lc->int_n_sep_by_space,
+               lc->int_n_sign_posn, L' ');
+#endif // !_LIBCPP_MSVCRT
+}
+
+void __do_nothing(void*) {}
+
+void __throw_runtime_error(const char* msg)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw runtime_error(msg);
+#else
+    (void)msg;
+    _VSTD::abort();
+#endif
+}
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS collate<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS collate<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_get<wchar_t>;
+
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_get<char>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_get<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_put<wchar_t>;
+
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_put<char>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_put<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get_byname<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put_byname<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<char, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<char, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<wchar_t, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<wchar_t, true>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<char, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<char, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<wchar_t, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<wchar_t, true>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_get<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_get<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_put<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_put<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<wchar_t>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<wchar_t, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char16_t, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char32_t, char, mbstate_t>;
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/memory.cpp b/lib/libcxx/src/memory.cpp
new file mode 100644
index 0000000000..633c9a6f56
--- /dev/null
+++ b/lib/libcxx/src/memory.cpp
@@ -0,0 +1,237 @@
+//===------------------------ memory.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "memory"
+#ifndef _LIBCPP_HAS_NO_THREADS
+#include "mutex"
+#include "thread"
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+#include "include/atomic_support.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+const allocator_arg_t allocator_arg = allocator_arg_t();
+
+bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {}
+
+const char*
+bad_weak_ptr::what() const _NOEXCEPT
+{
+    return "bad_weak_ptr";
+}
+
+__shared_count::~__shared_count()
+{
+}
+
+__shared_weak_count::~__shared_weak_count()
+{
+}
+
+#if defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
+void
+__shared_count::__add_shared() _NOEXCEPT
+{
+    __libcpp_atomic_refcount_increment(__shared_owners_);
+}
+
+bool
+__shared_count::__release_shared() _NOEXCEPT
+{
+    if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1)
+    {
+        __on_zero_shared();
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_weak_count::__add_shared() _NOEXCEPT
+{
+    __shared_count::__add_shared();
+}
+
+void
+__shared_weak_count::__add_weak() _NOEXCEPT
+{
+    __libcpp_atomic_refcount_increment(__shared_weak_owners_);
+}
+
+void
+__shared_weak_count::__release_shared() _NOEXCEPT
+{
+    if (__shared_count::__release_shared())
+        __release_weak();
+}
+
+#endif // _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
+
+void
+__shared_weak_count::__release_weak() _NOEXCEPT
+{
+    // NOTE: The acquire load here is an optimization of the very
+    // common case where a shared pointer is being destructed while
+    // having no other contended references.
+    //
+    // BENEFIT: We avoid expensive atomic stores like XADD and STREX
+    // in a common case.  Those instructions are slow and do nasty
+    // things to caches.
+    //
+    // IS THIS SAFE?  Yes.  During weak destruction, if we see that we
+    // are the last reference, we know that no-one else is accessing
+    // us. If someone were accessing us, then they would be doing so
+    // while the last shared / weak_ptr was being destructed, and
+    // that's undefined anyway.
+    //
+    // If we see anything other than a 0, then we have possible
+    // contention, and need to use an atomicrmw primitive.
+    // The same arguments don't apply for increment, where it is legal
+    // (though inadvisable) to share shared_ptr references between
+    // threads, and have them all get copied at once.  The argument
+    // also doesn't apply for __release_shared, because an outstanding
+    // weak_ptr::lock() could read / modify the shared count.
+    if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0)
+    {
+        // no need to do this store, because we are about
+        // to destroy everything.
+        //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);
+        __on_zero_shared_weak();
+    }
+    else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)
+        __on_zero_shared_weak();
+}
+
+__shared_weak_count*
+__shared_weak_count::lock() _NOEXCEPT
+{
+    long object_owners = __libcpp_atomic_load(&__shared_owners_);
+    while (object_owners != -1)
+    {
+        if (__libcpp_atomic_compare_exchange(&__shared_owners_,
+                                             &object_owners,
+                                             object_owners+1))
+            return this;
+    }
+    return nullptr;
+}
+
+#if !defined(_LIBCPP_NO_RTTI) || !defined(_LIBCPP_BUILD_STATIC)
+
+const void*
+__shared_weak_count::__get_deleter(const type_info&) const _NOEXCEPT
+{
+    return nullptr;
+}
+
+#endif  // _LIBCPP_NO_RTTI
+
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+
+_LIBCPP_SAFE_STATIC static const std::size_t __sp_mut_count = 16;
+_LIBCPP_SAFE_STATIC static __libcpp_mutex_t mut_back[__sp_mut_count] =
+{
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER
+};
+
+_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
+   : __lx(p)
+{
+}
+
+void
+__sp_mut::lock() _NOEXCEPT
+{
+    auto m = static_cast<__libcpp_mutex_t*>(__lx);
+    unsigned count = 0;
+    while (!__libcpp_mutex_trylock(m))
+    {
+        if (++count > 16)
+        {
+            __libcpp_mutex_lock(m);
+            break;
+        }
+        this_thread::yield();
+    }
+}
+
+void
+__sp_mut::unlock() _NOEXCEPT
+{
+    __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx));
+}
+
+__sp_mut&
+__get_sp_mut(const void* p)
+{
+    static __sp_mut muts[__sp_mut_count]
+    {
+        &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],
+        &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],
+        &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11],
+        &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15]
+    };
+    return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
+}
+
+#endif // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+
+void
+declare_reachable(void*)
+{
+}
+
+void
+declare_no_pointers(char*, size_t)
+{
+}
+
+void
+undeclare_no_pointers(char*, size_t)
+{
+}
+
+#if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE)
+pointer_safety get_pointer_safety() _NOEXCEPT
+{
+    return pointer_safety::relaxed;
+}
+#endif
+
+void*
+__undeclare_reachable(void* p)
+{
+    return p;
+}
+
+void*
+align(size_t alignment, size_t size, void*& ptr, size_t& space)
+{
+    void* r = nullptr;
+    if (size <= space)
+    {
+        char* p1 = static_cast<char*>(ptr);
+        char* p2 = reinterpret_cast<char*>(reinterpret_cast<size_t>(p1 + (alignment - 1)) & -alignment);
+        size_t d = static_cast<size_t>(p2 - p1);
+        if (d <= space - size)
+        {
+            r = p2;
+            ptr = r;
+            space -= d;
+        }
+    }
+    return r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/mutex.cpp b/lib/libcxx/src/mutex.cpp
new file mode 100644
index 0000000000..27a4fd8927
--- /dev/null
+++ b/lib/libcxx/src/mutex.cpp
@@ -0,0 +1,260 @@
+//===------------------------- mutex.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mutex"
+#include "limits"
+#include "system_error"
+#include "include/atomic_support.h"
+#include "__undef_macros"
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+const defer_lock_t  defer_lock{};
+const try_to_lock_t try_to_lock{};
+const adopt_lock_t  adopt_lock{};
+
+// ~mutex is defined elsewhere
+
+void
+mutex::lock()
+{
+    int ec = __libcpp_mutex_lock(&__m_);
+    if (ec)
+        __throw_system_error(ec, "mutex lock failed");
+}
+
+bool
+mutex::try_lock() _NOEXCEPT
+{
+    return __libcpp_mutex_trylock(&__m_);
+}
+
+void
+mutex::unlock() _NOEXCEPT
+{
+    int ec = __libcpp_mutex_unlock(&__m_);
+    (void)ec;
+    _LIBCPP_ASSERT(ec == 0, "call to mutex::unlock failed");
+}
+
+// recursive_mutex
+
+recursive_mutex::recursive_mutex()
+{
+    int ec = __libcpp_recursive_mutex_init(&__m_);
+    if (ec)
+        __throw_system_error(ec, "recursive_mutex constructor failed");
+}
+
+recursive_mutex::~recursive_mutex()
+{
+    int e = __libcpp_recursive_mutex_destroy(&__m_);
+    (void)e;
+    _LIBCPP_ASSERT(e == 0, "call to ~recursive_mutex() failed");
+}
+
+void
+recursive_mutex::lock()
+{
+    int ec = __libcpp_recursive_mutex_lock(&__m_);
+    if (ec)
+        __throw_system_error(ec, "recursive_mutex lock failed");
+}
+
+void
+recursive_mutex::unlock() _NOEXCEPT
+{
+    int e = __libcpp_recursive_mutex_unlock(&__m_);
+    (void)e;
+    _LIBCPP_ASSERT(e == 0, "call to recursive_mutex::unlock() failed");
+}
+
+bool
+recursive_mutex::try_lock() _NOEXCEPT
+{
+    return __libcpp_recursive_mutex_trylock(&__m_);
+}
+
+// timed_mutex
+
+timed_mutex::timed_mutex()
+    : __locked_(false)
+{
+}
+
+timed_mutex::~timed_mutex()
+{
+    lock_guard<mutex> _(__m_);
+}
+
+void
+timed_mutex::lock()
+{
+    unique_lock<mutex> lk(__m_);
+    while (__locked_)
+        __cv_.wait(lk);
+    __locked_ = true;
+}
+
+bool
+timed_mutex::try_lock() _NOEXCEPT
+{
+    unique_lock<mutex> lk(__m_, try_to_lock);
+    if (lk.owns_lock() && !__locked_)
+    {
+        __locked_ = true;
+        return true;
+    }
+    return false;
+}
+
+void
+timed_mutex::unlock() _NOEXCEPT
+{
+    lock_guard<mutex> _(__m_);
+    __locked_ = false;
+    __cv_.notify_one();
+}
+
+// recursive_timed_mutex
+
+recursive_timed_mutex::recursive_timed_mutex()
+    : __count_(0),
+      __id_{}
+{
+}
+
+recursive_timed_mutex::~recursive_timed_mutex()
+{
+    lock_guard<mutex> _(__m_);
+}
+
+void
+recursive_timed_mutex::lock()
+{
+    __thread_id id = this_thread::get_id();
+    unique_lock<mutex> lk(__m_);
+    if (id ==__id_)
+    {
+        if (__count_ == numeric_limits<size_t>::max())
+            __throw_system_error(EAGAIN, "recursive_timed_mutex lock limit reached");
+        ++__count_;
+        return;
+    }
+    while (__count_ != 0)
+        __cv_.wait(lk);
+    __count_ = 1;
+    __id_ = id;
+}
+
+bool
+recursive_timed_mutex::try_lock() _NOEXCEPT
+{
+    __thread_id id = this_thread::get_id();
+    unique_lock<mutex> lk(__m_, try_to_lock);
+    if (lk.owns_lock() && (__count_ == 0 || id == __id_))
+    {
+        if (__count_ == numeric_limits<size_t>::max())
+            return false;
+        ++__count_;
+        __id_ = id;
+        return true;
+    }
+    return false;
+}
+
+void
+recursive_timed_mutex::unlock() _NOEXCEPT
+{
+    unique_lock<mutex> lk(__m_);
+    if (--__count_ == 0)
+    {
+        __id_.__reset();
+        lk.unlock();
+        __cv_.notify_one();
+    }
+}
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+
+// If dispatch_once_f ever handles C++ exceptions, and if one can get to it
+// without illegal macros (unexpected macros not beginning with _UpperCase or
+// __lowercase), and if it stops spinning waiting threads, then call_once should
+// call into dispatch_once_f instead of here. Relevant radar this code needs to
+// keep in sync with:  7741191.
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+_LIBCPP_SAFE_STATIC static __libcpp_mutex_t mut = _LIBCPP_MUTEX_INITIALIZER;
+_LIBCPP_SAFE_STATIC static __libcpp_condvar_t cv = _LIBCPP_CONDVAR_INITIALIZER;
+#endif
+
+void __call_once(volatile once_flag::_State_type& flag, void* arg,
+                 void (*func)(void*))
+{
+#if defined(_LIBCPP_HAS_NO_THREADS)
+    if (flag == 0)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            flag = 1;
+            func(arg);
+            flag = ~once_flag::_State_type(0);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            flag = 0;
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    }
+#else // !_LIBCPP_HAS_NO_THREADS
+    __libcpp_mutex_lock(&mut);
+    while (flag == 1)
+        __libcpp_condvar_wait(&cv, &mut);
+    if (flag == 0)
+    {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            __libcpp_relaxed_store(&flag, once_flag::_State_type(1));
+            __libcpp_mutex_unlock(&mut);
+            func(arg);
+            __libcpp_mutex_lock(&mut);
+            __libcpp_atomic_store(&flag, ~once_flag::_State_type(0),
+                                  _AO_Release);
+            __libcpp_mutex_unlock(&mut);
+            __libcpp_condvar_broadcast(&cv);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __libcpp_mutex_lock(&mut);
+            __libcpp_relaxed_store(&flag, once_flag::_State_type(0));
+            __libcpp_mutex_unlock(&mut);
+            __libcpp_condvar_broadcast(&cv);
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    }
+    else
+        __libcpp_mutex_unlock(&mut);
+#endif // !_LIBCPP_HAS_NO_THREADS
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/mutex_destructor.cpp b/lib/libcxx/src/mutex_destructor.cpp
new file mode 100644
index 0000000000..2038d2bbe2
--- /dev/null
+++ b/lib/libcxx/src/mutex_destructor.cpp
@@ -0,0 +1,50 @@
+//===--------------------- mutex_destructor.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Define ~mutex.
+//
+// On some platforms ~mutex has been made trivial and the definition is only
+// provided for ABI compatibility.
+//
+// In order to avoid ODR violations within libc++ itself, we need to ensure
+// that *nothing* sees the non-trivial mutex declaration. For this reason
+// we re-declare the entire class in this file instead of using
+// _LIBCPP_BUILDING_LIBRARY to change the definition in the headers.
+
+#include "__config"
+#include "__threading_support"
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION)
+#define NEEDS_MUTEX_DESTRUCTOR
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef NEEDS_MUTEX_DESTRUCTOR
+class _LIBCPP_TYPE_VIS mutex
+{
+    __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
+
+public:
+    _LIBCPP_ALWAYS_INLINE _LIBCPP_INLINE_VISIBILITY
+    constexpr mutex() = default;
+    mutex(const mutex&) = delete;
+    mutex& operator=(const mutex&) = delete;
+    ~mutex() noexcept;
+};
+
+
+mutex::~mutex() _NOEXCEPT
+{
+    __libcpp_mutex_destroy(&__m_);
+}
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/new.cpp b/lib/libcxx/src/new.cpp
new file mode 100644
index 0000000000..901e785658
--- /dev/null
+++ b/lib/libcxx/src/new.cpp
@@ -0,0 +1,297 @@
+//===--------------------------- new.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdlib.h>
+
+#include "new"
+#include "include/atomic_support.h"
+
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#   if !defined(_LIBCPP_ABI_VCRUNTIME)
+#       include "support/runtime/new_handler_fallback.ipp"
+#   endif
+#elif defined(LIBCXX_BUILDING_LIBCXXABI)
+#   include <cxxabi.h>
+#elif defined(LIBCXXRT)
+#   include <cxxabi.h>
+#   include "support/runtime/new_handler_fallback.ipp"
+#elif defined(__GLIBCXX__)
+    // nothing to do
+#else
+#   include "support/runtime/new_handler_fallback.ipp"
+#endif
+
+namespace std
+{
+
+#ifndef __GLIBCXX__
+const nothrow_t nothrow{};
+#endif
+
+#ifndef LIBSTDCXX
+
+void
+__throw_bad_alloc()
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw bad_alloc();
+#else
+    _VSTD::abort();
+#endif
+}
+
+#endif // !LIBSTDCXX
+
+}  // std
+
+#if !defined(__GLIBCXX__) &&                                                   \
+    !defined(_LIBCPP_ABI_VCRUNTIME) &&      \
+    !defined(_LIBCPP_DISABLE_NEW_DELETE_DEFINITIONS)
+
+// Implement all new and delete operators as weak definitions
+// in this shared library, so that they can be overridden by programs
+// that define non-weak copies of the functions.
+
+_LIBCPP_WEAK
+void *
+operator new(std::size_t size) _THROW_BAD_ALLOC
+{
+    if (size == 0)
+        size = 1;
+    void* p;
+    while ((p = ::malloc(size)) == 0)
+    {
+        // If malloc fails and there is a new_handler,
+        // call it to try free up memory.
+        std::new_handler nh = std::get_new_handler();
+        if (nh)
+            nh();
+        else
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw std::bad_alloc();
+#else
+            break;
+#endif
+    }
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new(size_t size, const std::nothrow_t&) _NOEXCEPT
+{
+    void* p = 0;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        p = ::operator new(size);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size) _THROW_BAD_ALLOC
+{
+    return ::operator new(size);
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, const std::nothrow_t&) _NOEXCEPT
+{
+    void* p = 0;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        p = ::operator new[](size);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr) _NOEXCEPT
+{
+    ::free(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, const std::nothrow_t&) _NOEXCEPT
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, size_t) _NOEXCEPT
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr) _NOEXCEPT
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, const std::nothrow_t&) _NOEXCEPT
+{
+    ::operator delete[](ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, size_t) _NOEXCEPT
+{
+    ::operator delete[](ptr);
+}
+
+#if !defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION)
+
+_LIBCPP_WEAK
+void *
+operator new(std::size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
+{
+    if (size == 0)
+        size = 1;
+    if (static_cast<size_t>(alignment) < sizeof(void*))
+      alignment = std::align_val_t(sizeof(void*));
+    void* p;
+#if defined(_LIBCPP_MSVCRT_LIKE)
+    while ((p = _aligned_malloc(size, static_cast<size_t>(alignment))) == nullptr)
+#else
+    while (::posix_memalign(&p, static_cast<size_t>(alignment), size) != 0)
+#endif
+    {
+        // If posix_memalign fails and there is a new_handler,
+        // call it to try free up memory.
+        std::new_handler nh = std::get_new_handler();
+        if (nh)
+            nh();
+        else {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw std::bad_alloc();
+#else
+            p = nullptr; // posix_memalign doesn't initialize 'p' on failure
+            break;
+#endif
+        }
+    }
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
+{
+    void* p = 0;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        p = ::operator new(size, alignment);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
+{
+    return ::operator new(size, alignment);
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
+{
+    void* p = 0;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        p = ::operator new[](size, alignment);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, std::align_val_t) _NOEXCEPT
+{
+#if defined(_LIBCPP_MSVCRT_LIKE)
+    ::_aligned_free(ptr);
+#else
+    ::free(ptr);
+#endif
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, size_t, std::align_val_t alignment) _NOEXCEPT
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, std::align_val_t alignment) _NOEXCEPT
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
+{
+    ::operator delete[](ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, size_t, std::align_val_t alignment) _NOEXCEPT
+{
+    ::operator delete[](ptr, alignment);
+}
+
+#endif // !_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
+#endif // !__GLIBCXX__ && !_LIBCPP_ABI_VCRUNTIME && !_LIBCPP_DISABLE_NEW_DELETE_DEFINITIONS
diff --git a/lib/libcxx/src/optional.cpp b/lib/libcxx/src/optional.cpp
new file mode 100644
index 0000000000..3aaf5ea553
--- /dev/null
+++ b/lib/libcxx/src/optional.cpp
@@ -0,0 +1,41 @@
+//===------------------------ optional.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "optional"
+
+namespace std
+{
+
+bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
+
+const char* bad_optional_access::what() const _NOEXCEPT {
+  return "bad_optional_access";
+  }
+
+} // std
+
+
+#include <experimental/__config>
+
+//  Preserve std::experimental::bad_optional_access for ABI compatibility
+//  Even though it no longer exists in a header file
+_LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
+
+class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
+    : public std::logic_error
+{
+public:
+	bad_optional_access() : std::logic_error("Bad optional Access") {}
+
+//	Get the key function ~bad_optional_access() into the dylib
+    virtual ~bad_optional_access() _NOEXCEPT;
+};
+
+bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
+
+_LIBCPP_END_NAMESPACE_EXPERIMENTAL
diff --git a/lib/libcxx/src/random.cpp b/lib/libcxx/src/random.cpp
new file mode 100644
index 0000000000..04adc59f9b
--- /dev/null
+++ b/lib/libcxx/src/random.cpp
@@ -0,0 +1,178 @@
+//===-------------------------- random.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#if defined(_LIBCPP_USING_WIN32_RANDOM)
+// Must be defined before including stdlib.h to enable rand_s().
+#define _CRT_RAND_S
+#endif // defined(_LIBCPP_USING_WIN32_RANDOM)
+
+#include "random"
+#include "system_error"
+
+#if defined(__sun__)
+#define rename solaris_headers_are_broken
+#endif // defined(__sun__)
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#if defined(_LIBCPP_USING_GETENTROPY)
+#include <sys/random.h>
+#elif defined(_LIBCPP_USING_DEV_RANDOM)
+#include <fcntl.h>
+#include <unistd.h>
+#elif defined(_LIBCPP_USING_NACL_RANDOM)
+#include <nacl/nacl_random.h>
+#endif
+
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if defined(_LIBCPP_USING_GETENTROPY)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    int err = getentropy(&r, n);
+    if (err)
+        __throw_system_error(errno, "random_device getentropy failed");
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_ARC4_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    return arc4random();
+}
+
+#elif defined(_LIBCPP_USING_DEV_RANDOM)
+
+random_device::random_device(const string& __token)
+    : __f_(open(__token.c_str(), O_RDONLY))
+{
+    if (__f_ < 0)
+        __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+    close(__f_);
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    char* p = reinterpret_cast<char*>(&r);
+    while (n > 0)
+    {
+        ssize_t s = read(__f_, p, n);
+        if (s == 0)
+            __throw_system_error(ENODATA, "random_device got EOF");
+        if (s == -1)
+        {
+            if (errno != EINTR)
+                __throw_system_error(errno, "random_device got an unexpected error");
+            continue;
+        }
+        n -= static_cast<size_t>(s);
+        p += static_cast<size_t>(s);
+    }
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_NACL_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+    int error = nacl_secure_random_init();
+    if (error)
+        __throw_system_error(error, ("random device failed to open " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    size_t bytes_written;
+    int error = nacl_secure_random(&r, n, &bytes_written);
+    if (error != 0)
+        __throw_system_error(error, "random_device failed getting bytes");
+    else if (bytes_written != n)
+        __throw_runtime_error("random_device failed to obtain enough bytes");
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_WIN32_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    errno_t err = rand_s(&r);
+    if (err)
+        __throw_system_error(err, "random_device rand_s failed.");
+    return r;
+}
+
+#else
+#error "Random device not implemented for this architecture"
+#endif
+
+double
+random_device::entropy() const _NOEXCEPT
+{
+    return 0;
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/regex.cpp b/lib/libcxx/src/regex.cpp
new file mode 100644
index 0000000000..d31e494874
--- /dev/null
+++ b/lib/libcxx/src/regex.cpp
@@ -0,0 +1,316 @@
+//===-------------------------- regex.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "regex"
+#include "algorithm"
+#include "iterator"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+static
+const char*
+make_error_type_string(regex_constants::error_type ecode)
+{
+    switch (ecode)
+    {
+    case regex_constants::error_collate:
+        return "The expression contained an invalid collating element name.";
+    case regex_constants::error_ctype:
+        return "The expression contained an invalid character class name.";
+    case regex_constants::error_escape:
+        return "The expression contained an invalid escaped character, or a "
+               "trailing escape.";
+    case regex_constants::error_backref:
+        return "The expression contained an invalid back reference.";
+    case regex_constants::error_brack:
+        return "The expression contained mismatched [ and ].";
+    case regex_constants::error_paren:
+        return "The expression contained mismatched ( and ).";
+    case regex_constants::error_brace:
+        return "The expression contained mismatched { and }.";
+    case regex_constants::error_badbrace:
+        return "The expression contained an invalid range in a {} expression.";
+    case regex_constants::error_range:
+        return "The expression contained an invalid character range, "
+               "such as [b-a] in most encodings.";
+    case regex_constants::error_space:
+        return "There was insufficient memory to convert the expression into "
+               "a finite state machine.";
+    case regex_constants::error_badrepeat:
+        return "One of *?+{ was not preceded by a valid regular expression.";
+    case regex_constants::error_complexity:
+        return "The complexity of an attempted match against a regular "
+               "expression exceeded a pre-set level.";
+    case regex_constants::error_stack:
+        return "There was insufficient memory to determine whether the regular "
+               "expression could match the specified character sequence.";
+    case regex_constants::__re_err_grammar:
+        return "An invalid regex grammar has been requested.";
+    case regex_constants::__re_err_empty:
+        return "An empty regex is not allowed in the POSIX grammar.";
+    case regex_constants::__re_err_parse:
+        return "The parser did not consume the entire regular expression.";
+    default:
+        break;
+    }
+    return "Unknown error type";
+}
+
+regex_error::regex_error(regex_constants::error_type ecode)
+    : runtime_error(make_error_type_string(ecode)),
+      __code_(ecode)
+{}
+
+regex_error::~regex_error() throw() {}
+
+namespace {
+
+struct collationnames
+{
+    const char* elem_;
+    char char_;
+};
+
+const collationnames collatenames[] =
+{
+    {"A", 0x41},
+    {"B", 0x42},
+    {"C", 0x43},
+    {"D", 0x44},
+    {"E", 0x45},
+    {"F", 0x46},
+    {"G", 0x47},
+    {"H", 0x48},
+    {"I", 0x49},
+    {"J", 0x4a},
+    {"K", 0x4b},
+    {"L", 0x4c},
+    {"M", 0x4d},
+    {"N", 0x4e},
+    {"NUL", 0x00},
+    {"O", 0x4f},
+    {"P", 0x50},
+    {"Q", 0x51},
+    {"R", 0x52},
+    {"S", 0x53},
+    {"T", 0x54},
+    {"U", 0x55},
+    {"V", 0x56},
+    {"W", 0x57},
+    {"X", 0x58},
+    {"Y", 0x59},
+    {"Z", 0x5a},
+    {"a", 0x61},
+    {"alert", 0x07},
+    {"ampersand", 0x26},
+    {"apostrophe", 0x27},
+    {"asterisk", 0x2a},
+    {"b", 0x62},
+    {"backslash", 0x5c},
+    {"backspace", 0x08},
+    {"c", 0x63},
+    {"carriage-return", 0x0d},
+    {"circumflex", 0x5e},
+    {"circumflex-accent", 0x5e},
+    {"colon", 0x3a},
+    {"comma", 0x2c},
+    {"commercial-at", 0x40},
+    {"d", 0x64},
+    {"dollar-sign", 0x24},
+    {"e", 0x65},
+    {"eight", 0x38},
+    {"equals-sign", 0x3d},
+    {"exclamation-mark", 0x21},
+    {"f", 0x66},
+    {"five", 0x35},
+    {"form-feed", 0x0c},
+    {"four", 0x34},
+    {"full-stop", 0x2e},
+    {"g", 0x67},
+    {"grave-accent", 0x60},
+    {"greater-than-sign", 0x3e},
+    {"h", 0x68},
+    {"hyphen", 0x2d},
+    {"hyphen-minus", 0x2d},
+    {"i", 0x69},
+    {"j", 0x6a},
+    {"k", 0x6b},
+    {"l", 0x6c},
+    {"left-brace", 0x7b},
+    {"left-curly-bracket", 0x7b},
+    {"left-parenthesis", 0x28},
+    {"left-square-bracket", 0x5b},
+    {"less-than-sign", 0x3c},
+    {"low-line", 0x5f},
+    {"m", 0x6d},
+    {"n", 0x6e},
+    {"newline", 0x0a},
+    {"nine", 0x39},
+    {"number-sign", 0x23},
+    {"o", 0x6f},
+    {"one", 0x31},
+    {"p", 0x70},
+    {"percent-sign", 0x25},
+    {"period", 0x2e},
+    {"plus-sign", 0x2b},
+    {"q", 0x71},
+    {"question-mark", 0x3f},
+    {"quotation-mark", 0x22},
+    {"r", 0x72},
+    {"reverse-solidus", 0x5c},
+    {"right-brace", 0x7d},
+    {"right-curly-bracket", 0x7d},
+    {"right-parenthesis", 0x29},
+    {"right-square-bracket", 0x5d},
+    {"s", 0x73},
+    {"semicolon", 0x3b},
+    {"seven", 0x37},
+    {"six", 0x36},
+    {"slash", 0x2f},
+    {"solidus", 0x2f},
+    {"space", 0x20},
+    {"t", 0x74},
+    {"tab", 0x09},
+    {"three", 0x33},
+    {"tilde", 0x7e},
+    {"two", 0x32},
+    {"u", 0x75},
+    {"underscore", 0x5f},
+    {"v", 0x76},
+    {"vertical-line", 0x7c},
+    {"vertical-tab", 0x0b},
+    {"w", 0x77},
+    {"x", 0x78},
+    {"y", 0x79},
+    {"z", 0x7a},
+    {"zero", 0x30}
+};
+
+struct classnames
+{
+    const char* elem_;
+    regex_traits<char>::char_class_type mask_;
+};
+
+const classnames ClassNames[] =
+{
+    {"alnum",  ctype_base::alnum},
+    {"alpha",  ctype_base::alpha},
+    {"blank",  ctype_base::blank},
+    {"cntrl",  ctype_base::cntrl},
+    {"d",      ctype_base::digit},
+    {"digit",  ctype_base::digit},
+    {"graph",  ctype_base::graph},
+    {"lower",  ctype_base::lower},
+    {"print",  ctype_base::print},
+    {"punct",  ctype_base::punct},
+    {"s",      ctype_base::space},
+    {"space",  ctype_base::space},
+    {"upper",  ctype_base::upper},
+    {"w",      regex_traits<char>::__regex_word},
+    {"xdigit", ctype_base::xdigit}
+};
+
+struct use_strcmp
+{
+    bool operator()(const collationnames& x, const char* y)
+        {return strcmp(x.elem_, y) < 0;}
+    bool operator()(const classnames& x, const char* y)
+        {return strcmp(x.elem_, y) < 0;}
+};
+
+}
+
+string
+__get_collation_name(const char* s)
+{
+    const collationnames* i =
+            _VSTD::lower_bound(begin(collatenames), end(collatenames), s, use_strcmp());
+    string r;
+    if (i != end(collatenames) && strcmp(s, i->elem_) == 0)
+        r = char(i->char_);
+    return r;
+}
+
+regex_traits<char>::char_class_type
+__get_classname(const char* s, bool __icase)
+{
+    const classnames* i =
+            _VSTD::lower_bound(begin(ClassNames), end(ClassNames), s, use_strcmp());
+    regex_traits<char>::char_class_type r = 0;
+    if (i != end(ClassNames) && strcmp(s, i->elem_) == 0)
+    {
+        r = i->mask_;
+        if (r == regex_traits<char>::__regex_word)
+            r |= ctype_base::alnum | ctype_base::upper | ctype_base::lower;
+        else if (__icase)
+        {
+            if (r & (ctype_base::lower | ctype_base::upper))
+                r |= ctype_base::alpha;
+        }
+    }
+    return r;
+}
+
+template <>
+void
+__match_any_but_newline<char>::__exec(__state& __s) const
+{
+    if (__s.__current_ != __s.__last_)
+    {
+        switch (*__s.__current_)
+        {
+        case '\r':
+        case '\n':
+            __s.__do_ = __state::__reject;
+            __s.__node_ = nullptr;
+            break;
+        default:
+            __s.__do_ = __state::__accept_and_consume;
+            ++__s.__current_;
+            __s.__node_ = this->first();
+            break;
+        }
+    }
+    else
+    {
+        __s.__do_ = __state::__reject;
+        __s.__node_ = nullptr;
+    }
+}
+
+template <>
+void
+__match_any_but_newline<wchar_t>::__exec(__state& __s) const
+{
+    if (__s.__current_ != __s.__last_)
+    {
+        switch (*__s.__current_)
+        {
+        case '\r':
+        case '\n':
+        case 0x2028:
+        case 0x2029:
+            __s.__do_ = __state::__reject;
+            __s.__node_ = nullptr;
+            break;
+        default:
+            __s.__do_ = __state::__accept_and_consume;
+            ++__s.__current_;
+            __s.__node_ = this->first();
+            break;
+        }
+    }
+    else
+    {
+        __s.__do_ = __state::__reject;
+        __s.__node_ = nullptr;
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/shared_mutex.cpp b/lib/libcxx/src/shared_mutex.cpp
new file mode 100644
index 0000000000..5feef9f488
--- /dev/null
+++ b/lib/libcxx/src/shared_mutex.cpp
@@ -0,0 +1,118 @@
+//===---------------------- shared_mutex.cpp ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include "shared_mutex"
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Shared Mutex Base
+__shared_mutex_base::__shared_mutex_base()
+    : __state_(0)
+{
+}
+
+// Exclusive ownership
+
+void
+__shared_mutex_base::lock()
+{
+    unique_lock<mutex> lk(__mut_);
+    while (__state_ & __write_entered_)
+        __gate1_.wait(lk);
+    __state_ |= __write_entered_;
+    while (__state_ & __n_readers_)
+        __gate2_.wait(lk);
+}
+
+bool
+__shared_mutex_base::try_lock()
+{
+    unique_lock<mutex> lk(__mut_);
+    if (__state_ == 0)
+    {
+        __state_ = __write_entered_;
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_mutex_base::unlock()
+{
+    lock_guard<mutex> _(__mut_);
+    __state_ = 0;
+    __gate1_.notify_all();
+}
+
+// Shared ownership
+
+void
+__shared_mutex_base::lock_shared()
+{
+    unique_lock<mutex> lk(__mut_);
+    while ((__state_ & __write_entered_) || (__state_ & __n_readers_) == __n_readers_)
+        __gate1_.wait(lk);
+    unsigned num_readers = (__state_ & __n_readers_) + 1;
+    __state_ &= ~__n_readers_;
+    __state_ |= num_readers;
+}
+
+bool
+__shared_mutex_base::try_lock_shared()
+{
+    unique_lock<mutex> lk(__mut_);
+    unsigned num_readers = __state_ & __n_readers_;
+    if (!(__state_ & __write_entered_) && num_readers != __n_readers_)
+    {
+        ++num_readers;
+        __state_ &= ~__n_readers_;
+        __state_ |= num_readers;
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_mutex_base::unlock_shared()
+{
+    lock_guard<mutex> _(__mut_);
+    unsigned num_readers = (__state_ & __n_readers_) - 1;
+    __state_ &= ~__n_readers_;
+    __state_ |= num_readers;
+    if (__state_ & __write_entered_)
+    {
+        if (num_readers == 0)
+            __gate2_.notify_one();
+    }
+    else
+    {
+        if (num_readers == __n_readers_ - 1)
+            __gate1_.notify_one();
+    }
+}
+
+
+// Shared Timed Mutex
+// These routines are here for ABI stability
+shared_timed_mutex::shared_timed_mutex() : __base() {}
+void shared_timed_mutex::lock()     { return __base.lock(); }
+bool shared_timed_mutex::try_lock() { return __base.try_lock(); }
+void shared_timed_mutex::unlock()   { return __base.unlock(); }
+void shared_timed_mutex::lock_shared() { return __base.lock_shared(); }
+bool shared_timed_mutex::try_lock_shared() { return __base.try_lock_shared(); }
+void shared_timed_mutex::unlock_shared() { return __base.unlock_shared(); }
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS
diff --git a/lib/libcxx/src/stdexcept.cpp b/lib/libcxx/src/stdexcept.cpp
new file mode 100644
index 0000000000..f8f335f34a
--- /dev/null
+++ b/lib/libcxx/src/stdexcept.cpp
@@ -0,0 +1,19 @@
+//===------------------------ stdexcept.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "stdexcept"
+#include "new"
+#include "string"
+#include "system_error"
+
+
+#ifdef _LIBCPP_ABI_VCRUNTIME
+#include "support/runtime/stdexcept_vcruntime.ipp"
+#else
+#include "support/runtime/stdexcept_default.ipp"
+#endif
diff --git a/lib/libcxx/src/string.cpp b/lib/libcxx/src/string.cpp
new file mode 100644
index 0000000000..4802d63c81
--- /dev/null
+++ b/lib/libcxx/src/string.cpp
@@ -0,0 +1,458 @@
+//===------------------------- string.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "string"
+#include "charconv"
+#include "cstdlib"
+#include "cwchar"
+#include "cerrno"
+#include "limits"
+#include "stdexcept"
+#include <stdio.h>
+#include "__debug"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __basic_string_common<true>;
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<wchar_t>;
+
+template
+    string
+    operator+<char, char_traits<char>, allocator<char> >(char const*, string const&);
+
+namespace
+{
+
+template<typename T>
+inline
+void throw_helper( const string& msg )
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw T( msg );
+#else
+    fprintf(stderr, "%s\n", msg.c_str());
+    _VSTD::abort();
+#endif
+}
+
+inline
+void throw_from_string_out_of_range( const string& func )
+{
+    throw_helper<out_of_range>(func + ": out of range");
+}
+
+inline
+void throw_from_string_invalid_arg( const string& func )
+{
+    throw_helper<invalid_argument>(func + ": no conversion");
+}
+
+// as_integer
+
+template<typename V, typename S, typename F>
+inline
+V
+as_integer_helper(const string& func, const S& str, size_t* idx, int base, F f)
+{
+    typename S::value_type* ptr = nullptr;
+    const typename S::value_type* const p = str.c_str();
+    typename remove_reference<decltype(errno)>::type errno_save = errno;
+    errno = 0;
+    V r = f(p, &ptr, base);
+    swap(errno, errno_save);
+    if (errno_save == ERANGE)
+        throw_from_string_out_of_range(func);
+    if (ptr == p)
+        throw_from_string_invalid_arg(func);
+    if (idx)
+        *idx = static_cast<size_t>(ptr - p);
+    return r;
+}
+
+template<typename V, typename S>
+inline
+V
+as_integer(const string& func, const S& s, size_t* idx, int base);
+
+// string
+template<>
+inline
+int
+as_integer(const string& func, const string& s, size_t* idx, int base )
+{
+    // Use long as no Standard string to integer exists.
+    long r = as_integer_helper<long>( func, s, idx, base, strtol );
+    if (r < numeric_limits<int>::min() || numeric_limits<int>::max() < r)
+        throw_from_string_out_of_range(func);
+    return static_cast<int>(r);
+}
+
+template<>
+inline
+long
+as_integer(const string& func, const string& s, size_t* idx, int base )
+{
+    return as_integer_helper<long>( func, s, idx, base, strtol );
+}
+
+template<>
+inline
+unsigned long
+as_integer( const string& func, const string& s, size_t* idx, int base )
+{
+    return as_integer_helper<unsigned long>( func, s, idx, base, strtoul );
+}
+
+template<>
+inline
+long long
+as_integer( const string& func, const string& s, size_t* idx, int base )
+{
+    return as_integer_helper<long long>( func, s, idx, base, strtoll );
+}
+
+template<>
+inline
+unsigned long long
+as_integer( const string& func, const string& s, size_t* idx, int base )
+{
+    return as_integer_helper<unsigned long long>( func, s, idx, base, strtoull );
+}
+
+// wstring
+template<>
+inline
+int
+as_integer( const string& func, const wstring& s, size_t* idx, int base )
+{
+    // Use long as no Stantard string to integer exists.
+    long r = as_integer_helper<long>( func, s, idx, base, wcstol );
+    if (r < numeric_limits<int>::min() || numeric_limits<int>::max() < r)
+        throw_from_string_out_of_range(func);
+    return static_cast<int>(r);
+}
+
+template<>
+inline
+long
+as_integer( const string& func, const wstring& s, size_t* idx, int base )
+{
+    return as_integer_helper<long>( func, s, idx, base, wcstol );
+}
+
+template<>
+inline
+unsigned long
+as_integer( const string& func, const wstring& s, size_t* idx, int base )
+{
+    return as_integer_helper<unsigned long>( func, s, idx, base, wcstoul );
+}
+
+template<>
+inline
+long long
+as_integer( const string& func, const wstring& s, size_t* idx, int base )
+{
+    return as_integer_helper<long long>( func, s, idx, base, wcstoll );
+}
+
+template<>
+inline
+unsigned long long
+as_integer( const string& func, const wstring& s, size_t* idx, int base )
+{
+    return as_integer_helper<unsigned long long>( func, s, idx, base, wcstoull );
+}
+
+// as_float
+
+template<typename V, typename S, typename F>
+inline
+V
+as_float_helper(const string& func, const S& str, size_t* idx, F f )
+{
+    typename S::value_type* ptr = nullptr;
+    const typename S::value_type* const p = str.c_str();
+    typename remove_reference<decltype(errno)>::type errno_save = errno;
+    errno = 0;
+    V r = f(p, &ptr);
+    swap(errno, errno_save);
+    if (errno_save == ERANGE)
+        throw_from_string_out_of_range(func);
+    if (ptr == p)
+        throw_from_string_invalid_arg(func);
+    if (idx)
+        *idx = static_cast<size_t>(ptr - p);
+    return r;
+}
+
+template<typename V, typename S>
+inline
+V as_float( const string& func, const S& s, size_t* idx = nullptr );
+
+template<>
+inline
+float
+as_float( const string& func, const string& s, size_t* idx )
+{
+    return as_float_helper<float>( func, s, idx, strtof );
+}
+
+template<>
+inline
+double
+as_float(const string& func, const string& s, size_t* idx )
+{
+    return as_float_helper<double>( func, s, idx, strtod );
+}
+
+template<>
+inline
+long double
+as_float( const string& func, const string& s, size_t* idx )
+{
+    return as_float_helper<long double>( func, s, idx, strtold );
+}
+
+template<>
+inline
+float
+as_float( const string& func, const wstring& s, size_t* idx )
+{
+    return as_float_helper<float>( func, s, idx, wcstof );
+}
+
+template<>
+inline
+double
+as_float( const string& func, const wstring& s, size_t* idx )
+{
+    return as_float_helper<double>( func, s, idx, wcstod );
+}
+
+template<>
+inline
+long double
+as_float( const string& func, const wstring& s, size_t* idx )
+{
+    return as_float_helper<long double>( func, s, idx, wcstold );
+}
+
+}  // unnamed namespace
+
+int
+stoi(const string& str, size_t* idx, int base)
+{
+    return as_integer<int>( "stoi", str, idx, base );
+}
+
+int
+stoi(const wstring& str, size_t* idx, int base)
+{
+    return as_integer<int>( "stoi", str, idx, base );
+}
+
+long
+stol(const string& str, size_t* idx, int base)
+{
+    return as_integer<long>( "stol", str, idx, base );
+}
+
+long
+stol(const wstring& str, size_t* idx, int base)
+{
+    return as_integer<long>( "stol", str, idx, base );
+}
+
+unsigned long
+stoul(const string& str, size_t* idx, int base)
+{
+    return as_integer<unsigned long>( "stoul", str, idx, base );
+}
+
+unsigned long
+stoul(const wstring& str, size_t* idx, int base)
+{
+    return as_integer<unsigned long>( "stoul", str, idx, base );
+}
+
+long long
+stoll(const string& str, size_t* idx, int base)
+{
+    return as_integer<long long>( "stoll", str, idx, base );
+}
+
+long long
+stoll(const wstring& str, size_t* idx, int base)
+{
+    return as_integer<long long>( "stoll", str, idx, base );
+}
+
+unsigned long long
+stoull(const string& str, size_t* idx, int base)
+{
+    return as_integer<unsigned long long>( "stoull", str, idx, base );
+}
+
+unsigned long long
+stoull(const wstring& str, size_t* idx, int base)
+{
+    return as_integer<unsigned long long>( "stoull", str, idx, base );
+}
+
+float
+stof(const string& str, size_t* idx)
+{
+    return as_float<float>( "stof", str, idx );
+}
+
+float
+stof(const wstring& str, size_t* idx)
+{
+    return as_float<float>( "stof", str, idx );
+}
+
+double
+stod(const string& str, size_t* idx)
+{
+    return as_float<double>( "stod", str, idx );
+}
+
+double
+stod(const wstring& str, size_t* idx)
+{
+    return as_float<double>( "stod", str, idx );
+}
+
+long double
+stold(const string& str, size_t* idx)
+{
+    return as_float<long double>( "stold", str, idx );
+}
+
+long double
+stold(const wstring& str, size_t* idx)
+{
+    return as_float<long double>( "stold", str, idx );
+}
+
+// to_string
+
+namespace
+{
+
+// as_string
+
+template<typename S, typename P, typename V >
+inline
+S
+as_string(P sprintf_like, S s, const typename S::value_type* fmt, V a)
+{
+    typedef typename S::size_type size_type;
+    size_type available = s.size();
+    while (true)
+    {
+        int status = sprintf_like(&s[0], available + 1, fmt, a);
+        if ( status >= 0 )
+        {
+            size_type used = static_cast<size_type>(status);
+            if ( used <= available )
+            {
+                s.resize( used );
+                break;
+            }
+            available = used; // Assume this is advice of how much space we need.
+        }
+        else
+            available = available * 2 + 1;
+        s.resize(available);
+    }
+    return s;
+}
+
+template <class S>
+struct initial_string;
+
+template <>
+struct initial_string<string>
+{
+    string
+    operator()() const
+    {
+        string s;
+        s.resize(s.capacity());
+        return s;
+    }
+};
+
+template <>
+struct initial_string<wstring>
+{
+    wstring
+    operator()() const
+    {
+        wstring s(20, wchar_t());
+        s.resize(s.capacity());
+        return s;
+    }
+};
+
+typedef int (*wide_printf)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...);
+
+inline
+wide_printf
+get_swprintf()
+{
+#ifndef _LIBCPP_MSVCRT
+    return swprintf;
+#else
+    return static_cast<int (__cdecl*)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...)>(_snwprintf);
+#endif
+}
+
+template <typename S, typename V>
+S i_to_string(const V v)
+{
+//  numeric_limits::digits10 returns value less on 1 than desired for unsigned numbers.
+//  For example, for 1-byte unsigned value digits10 is 2 (999 can not be represented),
+//  so we need +1 here.
+    constexpr size_t bufsize = numeric_limits<V>::digits10 + 2;  // +1 for minus, +1 for digits10
+    char buf[bufsize];
+    const auto res = to_chars(buf, buf + bufsize, v);
+    _LIBCPP_ASSERT(res.ec == errc(), "bufsize must be large enough to accomodate the value");
+    return S(buf, res.ptr);
+}
+
+}  // unnamed namespace
+
+string  to_string (int val)                { return i_to_string< string>(val); }
+string  to_string (long val)               { return i_to_string< string>(val); }
+string  to_string (long long val)          { return i_to_string< string>(val); }
+string  to_string (unsigned val)           { return i_to_string< string>(val); }
+string  to_string (unsigned long val)      { return i_to_string< string>(val); }
+string  to_string (unsigned long long val) { return i_to_string< string>(val); }
+
+wstring to_wstring(int val)                { return i_to_string<wstring>(val); }
+wstring to_wstring(long val)               { return i_to_string<wstring>(val); }
+wstring to_wstring(long long val)          { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned val)           { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned long val)      { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned long long val) { return i_to_string<wstring>(val); }
+
+
+string  to_string (float val)       { return as_string(snprintf,       initial_string< string>()(),   "%f", val); }
+string  to_string (double val)      { return as_string(snprintf,       initial_string< string>()(),   "%f", val); }
+string  to_string (long double val) { return as_string(snprintf,       initial_string< string>()(),  "%Lf", val); }
+
+wstring to_wstring(float val)       { return as_string(get_swprintf(), initial_string<wstring>()(),  L"%f", val); }
+wstring to_wstring(double val)      { return as_string(get_swprintf(), initial_string<wstring>()(),  L"%f", val); }
+wstring to_wstring(long double val) { return as_string(get_swprintf(), initial_string<wstring>()(), L"%Lf", val); }
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/strstream.cpp b/lib/libcxx/src/strstream.cpp
new file mode 100644
index 0000000000..ae66806833
--- /dev/null
+++ b/lib/libcxx/src/strstream.cpp
@@ -0,0 +1,335 @@
+//===------------------------ strstream.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "strstream"
+#include "algorithm"
+#include "climits"
+#include "cstring"
+#include "cstdlib"
+#include "__debug"
+#include "__undef_macros"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+strstreambuf::strstreambuf(streamsize __alsize)
+    : __strmode_(__dynamic),
+      __alsize_(__alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+}
+
+strstreambuf::strstreambuf(void* (*__palloc)(size_t), void (*__pfree)(void*))
+    : __strmode_(__dynamic),
+      __alsize_(__default_alsize),
+      __palloc_(__palloc),
+      __pfree_(__pfree)
+{
+}
+
+void
+strstreambuf::__init(char* __gnext, streamsize __n, char* __pbeg)
+{
+    if (__n == 0)
+        __n = static_cast<streamsize>(strlen(__gnext));
+    else if (__n < 0)
+        __n = INT_MAX;
+    if (__pbeg == nullptr)
+        setg(__gnext, __gnext, __gnext + __n);
+    else
+    {
+        setg(__gnext, __gnext, __pbeg);
+        setp(__pbeg, __pbeg + __n);
+    }
+}
+
+strstreambuf::strstreambuf(char* __gnext, streamsize __n, char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(__gnext, __n, __pbeg);
+}
+
+strstreambuf::strstreambuf(const char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(__gnext), __n, nullptr);
+}
+
+strstreambuf::strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, reinterpret_cast<char*>(__pbeg));
+}
+
+strstreambuf::strstreambuf(const signed char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, nullptr);
+}
+
+strstreambuf::strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, reinterpret_cast<char*>(__pbeg));
+}
+
+strstreambuf::strstreambuf(const unsigned char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, nullptr);
+}
+
+strstreambuf::~strstreambuf()
+{
+    if (eback() && (__strmode_ & __allocated) != 0 && (__strmode_ & __frozen) == 0)
+    {
+        if (__pfree_)
+            __pfree_(eback());
+        else
+            delete [] eback();
+    }
+}
+
+void
+strstreambuf::swap(strstreambuf& __rhs)
+{
+    streambuf::swap(__rhs);
+    _VSTD::swap(__strmode_, __rhs.__strmode_);
+    _VSTD::swap(__alsize_, __rhs.__alsize_);
+    _VSTD::swap(__palloc_, __rhs.__palloc_);
+    _VSTD::swap(__pfree_, __rhs.__pfree_);
+}
+
+void
+strstreambuf::freeze(bool __freezefl)
+{
+    if (__strmode_ & __dynamic)
+    {
+        if (__freezefl)
+            __strmode_ |= __frozen;
+        else
+            __strmode_ &= ~__frozen;
+    }
+}
+
+char*
+strstreambuf::str()
+{
+    if (__strmode_ & __dynamic)
+        __strmode_ |= __frozen;
+    return eback();
+}
+
+int
+strstreambuf::pcount() const
+{
+    return static_cast<int>(pptr() - pbase());
+}
+
+strstreambuf::int_type
+strstreambuf::overflow(int_type __c)
+{
+    if (__c == EOF)
+        return int_type(0);
+    if (pptr() == epptr())
+    {
+        if ((__strmode_ & __dynamic) == 0 || (__strmode_ & __frozen) != 0)
+            return int_type(EOF);
+        size_t old_size = static_cast<size_t> ((epptr() ? epptr() : egptr()) - eback());
+        size_t new_size = max<size_t>(static_cast<size_t>(__alsize_), 2*old_size);
+        if (new_size == 0)
+            new_size = __default_alsize;
+        char* buf = nullptr;
+        if (__palloc_)
+            buf = static_cast<char*>(__palloc_(new_size));
+        else
+            buf = new char[new_size];
+        if (buf == nullptr)
+            return int_type(EOF);
+        if (old_size != 0) {
+            _LIBCPP_ASSERT(eback(), "overflow copying from NULL");
+            memcpy(buf, eback(), static_cast<size_t>(old_size));
+        }
+        ptrdiff_t ninp = gptr()  - eback();
+        ptrdiff_t einp = egptr() - eback();
+        ptrdiff_t nout = pptr()  - pbase();
+        if (__strmode_ & __allocated)
+        {
+            if (__pfree_)
+                __pfree_(eback());
+            else
+                delete [] eback();
+        }
+        setg(buf, buf + ninp, buf + einp);
+        setp(buf + einp, buf + new_size);
+        __pbump(nout);
+        __strmode_ |= __allocated;
+    }
+    *pptr() = static_cast<char>(__c);
+    pbump(1);
+    return int_type(static_cast<unsigned char>(__c));
+}
+
+strstreambuf::int_type
+strstreambuf::pbackfail(int_type __c)
+{
+    if (eback() == gptr())
+        return EOF;
+    if (__c == EOF)
+    {
+        gbump(-1);
+        return int_type(0);
+    }
+    if (__strmode_ & __constant)
+    {
+        if (gptr()[-1] == static_cast<char>(__c))
+        {
+            gbump(-1);
+            return __c;
+        }
+        return EOF;
+    }
+    gbump(-1);
+    *gptr() = static_cast<char>(__c);
+    return __c;
+}
+
+strstreambuf::int_type
+strstreambuf::underflow()
+{
+    if (gptr() == egptr())
+    {
+        if (egptr() >= pptr())
+            return EOF;
+        setg(eback(), gptr(), pptr());
+    }
+    return int_type(static_cast<unsigned char>(*gptr()));
+}
+
+strstreambuf::pos_type
+strstreambuf::seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __which)
+{
+    off_type __p(-1);
+    bool pos_in = (__which & ios::in) != 0;
+    bool pos_out = (__which & ios::out) != 0;
+    bool legal = false;
+    switch (__way)
+    {
+    case ios::beg:
+    case ios::end:
+        if (pos_in || pos_out)
+            legal = true;
+        break;
+    case ios::cur:
+        if (pos_in != pos_out)
+            legal = true;
+        break;
+    }
+    if (pos_in && gptr() == nullptr)
+        legal = false;
+    if (pos_out && pptr() == nullptr)
+        legal = false;
+    if (legal)
+    {
+        off_type newoff;
+        char* seekhigh = epptr() ? epptr() : egptr();
+        switch (__way)
+        {
+        case ios::beg:
+            newoff = 0;
+            break;
+        case ios::cur:
+            newoff = (pos_in ? gptr() : pptr()) - eback();
+            break;
+        case ios::end:
+            newoff = seekhigh - eback();
+            break;
+        default:
+            _LIBCPP_UNREACHABLE();
+        }
+        newoff += __off;
+        if (0 <= newoff && newoff <= seekhigh - eback())
+        {
+            char* newpos = eback() + newoff;
+            if (pos_in)
+                setg(eback(), newpos, _VSTD::max(newpos, egptr()));
+            if (pos_out)
+            {
+                // min(pbase, newpos), newpos, epptr()
+                __off = epptr() - newpos;
+                setp(min(pbase(), newpos), epptr());
+                __pbump((epptr() - pbase()) - __off);
+            }
+            __p = newoff;
+        }
+    }
+    return pos_type(__p);
+}
+
+strstreambuf::pos_type
+strstreambuf::seekpos(pos_type __sp, ios_base::openmode __which)
+{
+    off_type __p(-1);
+    bool pos_in = (__which & ios::in) != 0;
+    bool pos_out = (__which & ios::out) != 0;
+    if (pos_in || pos_out)
+    {
+        if (!((pos_in && gptr() == nullptr) || (pos_out && pptr() == nullptr)))
+        {
+            off_type newoff = __sp;
+            char* seekhigh = epptr() ? epptr() : egptr();
+            if (0 <= newoff && newoff <= seekhigh - eback())
+            {
+                char* newpos = eback() + newoff;
+                if (pos_in)
+                    setg(eback(), newpos, _VSTD::max(newpos, egptr()));
+                if (pos_out)
+                {
+                    // min(pbase, newpos), newpos, epptr()
+                    off_type temp = epptr() - newpos;
+                    setp(min(pbase(), newpos), epptr());
+                    __pbump((epptr() - pbase()) - temp);
+                }
+                __p = newoff;
+            }
+        }
+    }
+    return pos_type(__p);
+}
+
+istrstream::~istrstream()
+{
+}
+
+ostrstream::~ostrstream()
+{
+}
+
+strstream::~strstream()
+{
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/support/runtime/exception_fallback.ipp b/lib/libcxx/src/support/runtime/exception_fallback.ipp
new file mode 100644
index 0000000000..376a0381f5
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_fallback.ipp
@@ -0,0 +1,164 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdio>
+
+namespace std {
+
+_LIBCPP_SAFE_STATIC static std::terminate_handler  __terminate_handler;
+_LIBCPP_SAFE_STATIC static std::unexpected_handler __unexpected_handler;
+
+
+// libcxxrt provides implementations of these functions itself.
+unexpected_handler
+set_unexpected(unexpected_handler func) _NOEXCEPT
+{
+  return __libcpp_atomic_exchange(&__unexpected_handler, func);
+}
+
+unexpected_handler
+get_unexpected() _NOEXCEPT
+{
+  return __libcpp_atomic_load(&__unexpected_handler);
+
+}
+
+_LIBCPP_NORETURN
+void unexpected()
+{
+    (*get_unexpected())();
+    // unexpected handler should not return
+    terminate();
+}
+
+terminate_handler
+set_terminate(terminate_handler func) _NOEXCEPT
+{
+  return __libcpp_atomic_exchange(&__terminate_handler, func);
+}
+
+terminate_handler
+get_terminate() _NOEXCEPT
+{
+  return __libcpp_atomic_load(&__terminate_handler);
+}
+
+#ifndef __EMSCRIPTEN__ // We provide this in JS
+_LIBCPP_NORETURN
+void
+terminate() _NOEXCEPT
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        (*get_terminate())();
+        // handler should not return
+        fprintf(stderr, "terminate_handler unexpectedly returned\n");
+        ::abort();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        // handler should not throw exception
+        fprintf(stderr, "terminate_handler unexpectedly threw an exception\n");
+        ::abort();
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+#endif // !__EMSCRIPTEN__
+
+#if !defined(__EMSCRIPTEN__)
+bool uncaught_exception() _NOEXCEPT { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() _NOEXCEPT
+{
+#warning uncaught_exception not yet implemented
+  fprintf(stderr, "uncaught_exceptions not yet implemented\n");
+  ::abort();
+}
+#endif // !__EMSCRIPTEN__
+
+
+exception::~exception() _NOEXCEPT
+{
+}
+
+const char* exception::what() const _NOEXCEPT
+{
+  return "std::exception";
+}
+
+bad_exception::~bad_exception() _NOEXCEPT
+{
+}
+
+const char* bad_exception::what() const _NOEXCEPT
+{
+  return "std::bad_exception";
+}
+
+
+bad_alloc::bad_alloc() _NOEXCEPT
+{
+}
+
+bad_alloc::~bad_alloc() _NOEXCEPT
+{
+}
+
+const char*
+bad_alloc::what() const _NOEXCEPT
+{
+    return "std::bad_alloc";
+}
+
+bad_array_new_length::bad_array_new_length() _NOEXCEPT
+{
+}
+
+bad_array_new_length::~bad_array_new_length() _NOEXCEPT
+{
+}
+
+const char*
+bad_array_new_length::what() const _NOEXCEPT
+{
+    return "bad_array_new_length";
+}
+
+bad_cast::bad_cast() _NOEXCEPT
+{
+}
+
+bad_typeid::bad_typeid() _NOEXCEPT
+{
+}
+
+bad_cast::~bad_cast() _NOEXCEPT
+{
+}
+
+const char*
+bad_cast::what() const _NOEXCEPT
+{
+  return "std::bad_cast";
+}
+
+bad_typeid::~bad_typeid() _NOEXCEPT
+{
+}
+
+const char*
+bad_typeid::what() const _NOEXCEPT
+{
+  return "std::bad_typeid";
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_glibcxx.ipp b/lib/libcxx/src/support/runtime/exception_glibcxx.ipp
new file mode 100644
index 0000000000..4bf3c4d877
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_glibcxx.ipp
@@ -0,0 +1,32 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __GLIBCXX__
+#error header can only be used when targeting libstdc++ or libsupc++
+#endif
+
+namespace std {
+
+bad_alloc::bad_alloc() _NOEXCEPT
+{
+}
+
+bad_array_new_length::bad_array_new_length() _NOEXCEPT
+{
+}
+
+bad_cast::bad_cast() _NOEXCEPT
+{
+}
+
+bad_typeid::bad_typeid() _NOEXCEPT
+{
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_libcxxabi.ipp b/lib/libcxx/src/support/runtime/exception_libcxxabi.ipp
new file mode 100644
index 0000000000..6bc049bf38
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_libcxxabi.ipp
@@ -0,0 +1,27 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPPABI_VERSION
+#error this header can only be used with libc++abi
+#endif
+
+namespace std {
+
+bool uncaught_exception() _NOEXCEPT { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() _NOEXCEPT
+{
+# if _LIBCPPABI_VERSION > 1001
+    return __cxa_uncaught_exceptions();
+# else
+    return __cxa_uncaught_exception() ? 1 : 0;
+# endif
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_libcxxrt.ipp b/lib/libcxx/src/support/runtime/exception_libcxxrt.ipp
new file mode 100644
index 0000000000..0ebffdedba
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_libcxxrt.ipp
@@ -0,0 +1,25 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBCXXRT
+#error this header may only be used when targeting libcxxrt
+#endif
+
+namespace std {
+
+bad_exception::~bad_exception() _NOEXCEPT
+{
+}
+
+const char* bad_exception::what() const _NOEXCEPT
+{
+  return "std::bad_exception";
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_msvc.ipp b/lib/libcxx/src/support/runtime/exception_msvc.ipp
new file mode 100644
index 0000000000..7315b8261b
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_msvc.ipp
@@ -0,0 +1,163 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_ABI_MICROSOFT
+#error this header can only be used when targeting the MSVC ABI
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+
+extern "C" {
+typedef void (__cdecl* terminate_handler)();
+_LIBCPP_CRT_FUNC terminate_handler __cdecl set_terminate(
+    terminate_handler _NewTerminateHandler) throw();
+_LIBCPP_CRT_FUNC terminate_handler __cdecl _get_terminate();
+
+typedef void (__cdecl* unexpected_handler)();
+unexpected_handler __cdecl set_unexpected(
+    unexpected_handler _NewUnexpectedHandler) throw();
+unexpected_handler __cdecl _get_unexpected();
+
+int __cdecl __uncaught_exceptions();
+}
+
+namespace std {
+
+unexpected_handler
+set_unexpected(unexpected_handler func) _NOEXCEPT {
+  return ::set_unexpected(func);
+}
+
+unexpected_handler get_unexpected() _NOEXCEPT {
+  return ::_get_unexpected();
+}
+
+_LIBCPP_NORETURN
+void unexpected() {
+    (*get_unexpected())();
+    // unexpected handler should not return
+    terminate();
+}
+
+terminate_handler set_terminate(terminate_handler func) _NOEXCEPT {
+  return ::set_terminate(func);
+}
+
+terminate_handler get_terminate() _NOEXCEPT {
+  return ::_get_terminate();
+}
+
+_LIBCPP_NORETURN
+void terminate() _NOEXCEPT
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        (*get_terminate())();
+        // handler should not return
+        fprintf(stderr, "terminate_handler unexpectedly returned\n");
+        ::abort();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        // handler should not throw exception
+        fprintf(stderr, "terminate_handler unexpectedly threw an exception\n");
+        ::abort();
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+bool uncaught_exception() _NOEXCEPT { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() _NOEXCEPT {
+    return __uncaught_exceptions();
+}
+
+#if !defined(_LIBCPP_ABI_VCRUNTIME)
+bad_cast::bad_cast() _NOEXCEPT
+{
+}
+
+bad_cast::~bad_cast() _NOEXCEPT
+{
+}
+
+const char *
+bad_cast::what() const _NOEXCEPT
+{
+  return "std::bad_cast";
+}
+
+bad_typeid::bad_typeid() _NOEXCEPT
+{
+}
+
+bad_typeid::~bad_typeid() _NOEXCEPT
+{
+}
+
+const char *
+bad_typeid::what() const _NOEXCEPT
+{
+  return "std::bad_typeid";
+}
+
+exception::~exception() _NOEXCEPT
+{
+}
+
+const char* exception::what() const _NOEXCEPT
+{
+  return "std::exception";
+}
+
+
+bad_exception::~bad_exception() _NOEXCEPT
+{
+}
+
+const char* bad_exception::what() const _NOEXCEPT
+{
+  return "std::bad_exception";
+}
+
+
+bad_alloc::bad_alloc() _NOEXCEPT
+{
+}
+
+bad_alloc::~bad_alloc() _NOEXCEPT
+{
+}
+
+const char*
+bad_alloc::what() const _NOEXCEPT
+{
+    return "std::bad_alloc";
+}
+
+bad_array_new_length::bad_array_new_length() _NOEXCEPT
+{
+}
+
+bad_array_new_length::~bad_array_new_length() _NOEXCEPT
+{
+}
+
+const char*
+bad_array_new_length::what() const _NOEXCEPT
+{
+    return "bad_array_new_length";
+}
+#endif // !_LIBCPP_ABI_VCRUNTIME
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp b/lib/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp
new file mode 100644
index 0000000000..82a8e6972f
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp
@@ -0,0 +1,73 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef HAVE_DEPENDENT_EH_ABI
+#error this header may only be used with libc++abi or libcxxrt
+#endif
+
+namespace std {
+
+exception_ptr::~exception_ptr() _NOEXCEPT {
+  __cxa_decrement_exception_refcount(__ptr_);
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) _NOEXCEPT
+    : __ptr_(other.__ptr_)
+{
+    __cxa_increment_exception_refcount(__ptr_);
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) _NOEXCEPT
+{
+    if (__ptr_ != other.__ptr_)
+    {
+        __cxa_increment_exception_refcount(other.__ptr_);
+        __cxa_decrement_exception_refcount(__ptr_);
+        __ptr_ = other.__ptr_;
+    }
+    return *this;
+}
+
+nested_exception::nested_exception() _NOEXCEPT
+    : __ptr_(current_exception())
+{
+}
+
+nested_exception::~nested_exception() _NOEXCEPT
+{
+}
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+    if (__ptr_ == nullptr)
+        terminate();
+    rethrow_exception(__ptr_);
+}
+
+exception_ptr current_exception() _NOEXCEPT
+{
+    // be nicer if there was a constructor that took a ptr, then
+    // this whole function would be just:
+    //    return exception_ptr(__cxa_current_primary_exception());
+    exception_ptr ptr;
+    ptr.__ptr_ = __cxa_current_primary_exception();
+    return ptr;
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+    __cxa_rethrow_primary_exception(p.__ptr_);
+    // if p.__ptr_ is NULL, above returns so we terminate
+    terminate();
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_pointer_glibcxx.ipp b/lib/libcxx/src/support/runtime/exception_pointer_glibcxx.ipp
new file mode 100644
index 0000000000..3abc137c67
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_pointer_glibcxx.ipp
@@ -0,0 +1,77 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// libsupc++ does not implement the dependent EH ABI and the functionality
+// it uses to implement std::exception_ptr (which it declares as an alias of
+// std::__exception_ptr::exception_ptr) is not directly exported to clients. So
+// we have little choice but to hijack std::__exception_ptr::exception_ptr's
+// (which fortunately has the same layout as our std::exception_ptr) copy
+// constructor, assignment operator and destructor (which are part of its
+// stable ABI), and its rethrow_exception(std::__exception_ptr::exception_ptr)
+// function.
+
+namespace std {
+
+namespace __exception_ptr
+{
+
+struct exception_ptr
+{
+    void* __ptr_;
+
+    exception_ptr(const exception_ptr&) _NOEXCEPT;
+    exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
+    ~exception_ptr() _NOEXCEPT;
+};
+
+}
+
+_LIBCPP_NORETURN void rethrow_exception(__exception_ptr::exception_ptr);
+
+exception_ptr::~exception_ptr() _NOEXCEPT
+{
+    reinterpret_cast<__exception_ptr::exception_ptr*>(this)->~exception_ptr();
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) _NOEXCEPT
+    : __ptr_(other.__ptr_)
+{
+    new (reinterpret_cast<void*>(this)) __exception_ptr::exception_ptr(
+        reinterpret_cast<const __exception_ptr::exception_ptr&>(other));
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) _NOEXCEPT
+{
+    *reinterpret_cast<__exception_ptr::exception_ptr*>(this) =
+        reinterpret_cast<const __exception_ptr::exception_ptr&>(other);
+    return *this;
+}
+
+nested_exception::nested_exception() _NOEXCEPT
+    : __ptr_(current_exception())
+{
+}
+
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+    if (__ptr_ == nullptr)
+        terminate();
+    rethrow_exception(__ptr_);
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+    rethrow_exception(reinterpret_cast<__exception_ptr::exception_ptr&>(p));
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_pointer_msvc.ipp b/lib/libcxx/src/support/runtime/exception_pointer_msvc.ipp
new file mode 100644
index 0000000000..b1a3695223
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_pointer_msvc.ipp
@@ -0,0 +1,86 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+#include <stdlib.h>
+
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCreate(void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrDestroy(void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCopy(void*, const void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrAssign(void*, const void*);
+_LIBCPP_CRT_FUNC bool __cdecl __ExceptionPtrCompare(const void*, const void*);
+_LIBCPP_CRT_FUNC bool __cdecl __ExceptionPtrToBool(const void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrSwap(void*, void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCurrentException(void*);
+[[noreturn]] _LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrRethrow(const void*);
+_LIBCPP_CRT_FUNC void __cdecl
+__ExceptionPtrCopyException(void*, const void*, const void*);
+
+namespace std {
+
+exception_ptr::exception_ptr() _NOEXCEPT { __ExceptionPtrCreate(this); }
+exception_ptr::exception_ptr(nullptr_t) _NOEXCEPT { __ExceptionPtrCreate(this); }
+
+exception_ptr::exception_ptr(const exception_ptr& __other) _NOEXCEPT {
+  __ExceptionPtrCopy(this, &__other);
+}
+exception_ptr& exception_ptr::operator=(const exception_ptr& __other) _NOEXCEPT {
+  __ExceptionPtrAssign(this, &__other);
+  return *this;
+}
+
+exception_ptr& exception_ptr::operator=(nullptr_t) _NOEXCEPT {
+  exception_ptr dummy;
+  __ExceptionPtrAssign(this, &dummy);
+  return *this;
+}
+
+exception_ptr::~exception_ptr() _NOEXCEPT { __ExceptionPtrDestroy(this); }
+
+exception_ptr::operator bool() const _NOEXCEPT {
+  return __ExceptionPtrToBool(this);
+}
+
+bool operator==(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT {
+  return __ExceptionPtrCompare(&__x, &__y);
+}
+
+
+void swap(exception_ptr& lhs, exception_ptr& rhs) _NOEXCEPT {
+  __ExceptionPtrSwap(&rhs, &lhs);
+}
+
+exception_ptr __copy_exception_ptr(void* __except, const void* __ptr) {
+  exception_ptr __ret = nullptr;
+  if (__ptr)
+    __ExceptionPtrCopyException(&__ret, __except, __ptr);
+  return __ret;
+}
+
+exception_ptr current_exception() _NOEXCEPT {
+  exception_ptr __ret;
+  __ExceptionPtrCurrentException(&__ret);
+  return __ret;
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p) { __ExceptionPtrRethrow(&p); }
+
+nested_exception::nested_exception() _NOEXCEPT : __ptr_(current_exception()) {}
+
+nested_exception::~nested_exception() _NOEXCEPT {}
+
+_LIBCPP_NORETURN
+void nested_exception::rethrow_nested() const {
+  if (__ptr_ == nullptr)
+    terminate();
+  rethrow_exception(__ptr_);
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/exception_pointer_unimplemented.ipp b/lib/libcxx/src/support/runtime/exception_pointer_unimplemented.ipp
new file mode 100644
index 0000000000..991bca9ecf
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/exception_pointer_unimplemented.ipp
@@ -0,0 +1,79 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+#include <stdlib.h>
+
+namespace std {
+
+exception_ptr::~exception_ptr() _NOEXCEPT
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) _NOEXCEPT
+    : __ptr_(other.__ptr_)
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) _NOEXCEPT
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+nested_exception::nested_exception() _NOEXCEPT
+    : __ptr_(current_exception())
+{
+}
+
+#if !defined(__GLIBCXX__)
+
+nested_exception::~nested_exception() _NOEXCEPT
+{
+}
+
+#endif
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+#if 0
+  if (__ptr_ == nullptr)
+      terminate();
+  rethrow_exception(__ptr_);
+#endif // FIXME
+}
+
+exception_ptr current_exception() _NOEXCEPT
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/new_handler_fallback.ipp b/lib/libcxx/src/support/runtime/new_handler_fallback.ipp
new file mode 100644
index 0000000000..7205093942
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/new_handler_fallback.ipp
@@ -0,0 +1,26 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+namespace std {
+
+_LIBCPP_SAFE_STATIC static std::new_handler __new_handler;
+
+new_handler
+set_new_handler(new_handler handler) _NOEXCEPT
+{
+    return __libcpp_atomic_exchange(&__new_handler, handler);
+}
+
+new_handler
+get_new_handler() _NOEXCEPT
+{
+    return __libcpp_atomic_load(&__new_handler);
+}
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/stdexcept_default.ipp b/lib/libcxx/src/support/runtime/stdexcept_default.ipp
new file mode 100644
index 0000000000..c827ca4c51
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/stdexcept_default.ipp
@@ -0,0 +1,64 @@
+//===--------------------- stdexcept_default.ipp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "../../include/refstring.h"
+
+/* For _LIBCPPABI_VERSION */
+#if !defined(_LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY) &&                           \
+    (defined(LIBCXX_BUILDING_LIBCXXABI) || defined(LIBCXXRT))
+#include <cxxabi.h>
+#endif
+
+static_assert(sizeof(std::__libcpp_refstring) == sizeof(const char*), "");
+
+namespace std // purposefully not using versioning namespace
+{
+
+logic_error::logic_error(const string& msg) : __imp_(msg.c_str()) {}
+
+logic_error::logic_error(const char* msg) : __imp_(msg) {}
+
+logic_error::logic_error(const logic_error& le) _NOEXCEPT : __imp_(le.__imp_) {}
+
+logic_error& logic_error::operator=(const logic_error& le) _NOEXCEPT {
+  __imp_ = le.__imp_;
+  return *this;
+}
+
+runtime_error::runtime_error(const string& msg) : __imp_(msg.c_str()) {}
+
+runtime_error::runtime_error(const char* msg) : __imp_(msg) {}
+
+runtime_error::runtime_error(const runtime_error& re) _NOEXCEPT
+    : __imp_(re.__imp_) {}
+
+runtime_error& runtime_error::operator=(const runtime_error& re) _NOEXCEPT {
+  __imp_ = re.__imp_;
+  return *this;
+}
+
+#if !defined(_LIBCPPABI_VERSION) && !defined(LIBSTDCXX)
+
+const char* logic_error::what() const _NOEXCEPT { return __imp_.c_str(); }
+
+const char* runtime_error::what() const _NOEXCEPT { return __imp_.c_str(); }
+
+logic_error::~logic_error() _NOEXCEPT {}
+domain_error::~domain_error() _NOEXCEPT {}
+invalid_argument::~invalid_argument() _NOEXCEPT {}
+length_error::~length_error() _NOEXCEPT {}
+out_of_range::~out_of_range() _NOEXCEPT {}
+
+runtime_error::~runtime_error() _NOEXCEPT {}
+range_error::~range_error() _NOEXCEPT {}
+overflow_error::~overflow_error() _NOEXCEPT {}
+underflow_error::~underflow_error() _NOEXCEPT {}
+
+#endif
+
+} // namespace std
diff --git a/lib/libcxx/src/support/runtime/stdexcept_vcruntime.ipp b/lib/libcxx/src/support/runtime/stdexcept_vcruntime.ipp
new file mode 100644
index 0000000000..94eed465ae
--- /dev/null
+++ b/lib/libcxx/src/support/runtime/stdexcept_vcruntime.ipp
@@ -0,0 +1,16 @@
+//===------------------- stdexcept_vcruntime.ipp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_ABI_VCRUNTIME
+#error This file may only be used when defering to vcruntime
+#endif
+
+namespace std {
+logic_error::logic_error(std::string const& s) : exception(s.c_str()) {}
+runtime_error::runtime_error(std::string const& s) : exception(s.c_str()) {}
+} // namespace std
diff --git a/lib/libcxx/src/support/solaris/README b/lib/libcxx/src/support/solaris/README
new file mode 100644
index 0000000000..89c887a3b4
--- /dev/null
+++ b/lib/libcxx/src/support/solaris/README
@@ -0,0 +1,4 @@
+This directory contains a partial implementation of the xlocale APIs for
+Solaris.  Some portions are lifted from FreeBSD libc, and so are covered by a
+2-clause BSD license instead of the MIT/UUIC license that the rest of libc++ is
+distributed under.
diff --git a/lib/libcxx/src/support/solaris/mbsnrtowcs.inc b/lib/libcxx/src/support/solaris/mbsnrtowcs.inc
new file mode 100644
index 0000000000..074045277c
--- /dev/null
+++ b/lib/libcxx/src/support/solaris/mbsnrtowcs.inc
@@ -0,0 +1,76 @@
+
+
+/*-
+ * As noted in the source, some portions of this implementation are copied from
+ * FreeBSD libc.  These are covered by the following copyright:
+ *
+ * Copyright (c) 2002-2004 Tim J. Robbins.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+size_t
+mbsnrtowcs_l(wchar_t * __restrict dst, const char ** __restrict src,
+    size_t nms, size_t len, mbstate_t * __restrict ps, locale_t loc)
+{
+  const char *s;
+  size_t nchr;
+  wchar_t wc;
+  size_t nb;
+  FIX_LOCALE(loc);
+
+  s = *src;
+  nchr = 0;
+
+  if (dst == NULL) {
+    for (;;) {
+      if ((nb = mbrtowc_l(&wc, s, nms, ps, loc)) == (size_t)-1)
+        /* Invalid sequence - mbrtowc() sets errno. */
+        return ((size_t)-1);
+      else if (nb == 0 || nb == (size_t)-2)
+        return (nchr);
+      s += nb;
+      nms -= nb;
+      nchr++;
+    }
+    /*NOTREACHED*/
+  }
+
+  while (len-- > 0) {
+    if ((nb = mbrtowc_l(dst, s, nms, ps, loc)) == (size_t)-1) {
+      *src = s;
+      return ((size_t)-1);
+    } else if (nb == (size_t)-2) {
+      *src = s + nms;
+      return (nchr);
+    } else if (nb == 0) {
+      *src = NULL;
+      return (nchr);
+    }
+    s += nb;
+    nms -= nb;
+    nchr++;
+    dst++;
+  }
+  *src = s;
+  return (nchr);
+}
diff --git a/lib/libcxx/src/support/solaris/wcsnrtombs.inc b/lib/libcxx/src/support/solaris/wcsnrtombs.inc
new file mode 100644
index 0000000000..239079e471
--- /dev/null
+++ b/lib/libcxx/src/support/solaris/wcsnrtombs.inc
@@ -0,0 +1,92 @@
+/*-
+ * Copyright (c) 2002-2004 Tim J. Robbins.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+
+size_t
+wcsnrtombs_l(char * __restrict dst, const wchar_t ** __restrict src,
+    size_t nwc, size_t len, mbstate_t * __restrict ps, locale_t loc)
+{
+  FIX_LOCALE(loc);
+  mbstate_t mbsbak;
+  char buf[MB_CUR_MAX_L(loc)];
+  const wchar_t *s;
+  size_t nbytes;
+  size_t nb;
+
+  s = *src;
+  nbytes = 0;
+
+  if (dst == NULL) {
+    while (nwc-- > 0) {
+      if ((nb = wcrtomb_l(buf, *s, ps, loc)) == (size_t)-1)
+        /* Invalid character - wcrtomb() sets errno. */
+        return ((size_t)-1);
+      else if (*s == L'\0')
+        return (nbytes + nb - 1);
+      s++;
+      nbytes += nb;
+    }
+    return (nbytes);
+  }
+
+  while (len > 0 && nwc-- > 0) {
+    if (len > (size_t)MB_CUR_MAX_L(loc)) {
+      /* Enough space to translate in-place. */
+      if ((nb = wcrtomb_l(dst, *s, ps, loc)) == (size_t)-1) {
+        *src = s;
+        return ((size_t)-1);
+      }
+    } else {
+      /*
+       * May not be enough space; use temp. buffer.
+       *
+       * We need to save a copy of the conversion state
+       * here so we can restore it if the multibyte
+       * character is too long for the buffer.
+       */
+      mbsbak = *ps;
+      if ((nb = wcrtomb_l(buf, *s, ps, loc)) == (size_t)-1) {
+        *src = s;
+        return ((size_t)-1);
+      }
+      if (nb > (int)len) {
+        /* MB sequence for character won't fit. */
+        *ps = mbsbak;
+        break;
+      }
+      memcpy(dst, buf, nb);
+    }
+    if (*s == L'\0') {
+      *src = NULL;
+      return (nbytes + nb - 1);
+    }
+    s++;
+    dst += nb;
+    len -= nb;
+    nbytes += nb;
+  }
+  *src = s;
+  return (nbytes);
+}
diff --git a/lib/libcxx/src/support/solaris/xlocale.cpp b/lib/libcxx/src/support/solaris/xlocale.cpp
new file mode 100644
index 0000000000..d68a39f4df
--- /dev/null
+++ b/lib/libcxx/src/support/solaris/xlocale.cpp
@@ -0,0 +1,68 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifdef __sun__
+
+#include "support/solaris/xlocale.h"
+#include <stdarg.h>
+#include <stdio.h>
+#include <sys/localedef.h>
+
+extern "C" {
+
+int isxdigit_l(int __c, locale_t __l) {
+    return isxdigit(__c);
+}
+
+int iswxdigit_l(wint_t __c, locale_t __l) {
+    return isxdigit(__c);
+}
+
+// FIXME: This disregards the locale, which is Very Wrong
+#define vsnprintf_l(__s, __n, __l, __format, __va)  \
+    vsnprintf(__s, __n, __format, __va)
+
+int snprintf_l(char *__s, size_t __n, locale_t __l, const char *__format, ...)
+{
+  va_list __va;
+  va_start(__va, __format);
+  int __res = vsnprintf_l(__s, __n , __l, __format, __va);
+  va_end(__va);
+  return __res;
+}
+
+int asprintf_l(char **__s, locale_t __l, const char *__format, ...) {
+  va_list __va;
+  va_start(__va, __format);
+  // FIXME:
+  int __res = vasprintf(__s, __format, __va);
+  va_end(__va);
+  return __res;
+}
+
+int sscanf_l(const char *__s, locale_t __l, const char *__format, ...) {
+  va_list __va;
+  va_start(__va, __format);
+  // FIXME:
+  int __res = vsscanf(__s, __format, __va);
+  va_end(__va);
+  return __res;
+}
+
+size_t mbrtowc_l(wchar_t *__pwc, const char *__pmb,
+                 size_t __max, mbstate_t *__ps, locale_t __loc) {
+  return mbrtowc(__pwc, __pmb, __max, __ps);
+}
+
+struct lconv *localeconv_l(locale_t __l) {
+  return localeconv();
+}
+
+};
+
+#endif // __sun__
diff --git a/lib/libcxx/src/support/win32/locale_win32.cpp b/lib/libcxx/src/support/win32/locale_win32.cpp
new file mode 100644
index 0000000000..b7062db352
--- /dev/null
+++ b/lib/libcxx/src/support/win32/locale_win32.cpp
@@ -0,0 +1,139 @@
+// -*- C++ -*-
+//===-------------------- support/win32/locale_win32.cpp ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <locale>
+#include <cstdarg> // va_start, va_end
+#include <memory>
+#include <type_traits>
+
+int __libcpp_vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
+
+using std::__libcpp_locale_guard;
+
+// FIXME: base currently unused. Needs manual work to construct the new locale
+locale_t newlocale( int mask, const char * locale, locale_t /*base*/ )
+{
+    return {_create_locale( LC_ALL, locale ), locale};
+}
+
+decltype(MB_CUR_MAX) MB_CUR_MAX_L( locale_t __l )
+{
+#if defined(_LIBCPP_MSVCRT)
+  return ___mb_cur_max_l_func(__l);
+#else
+  __libcpp_locale_guard __current(__l);
+  return MB_CUR_MAX;
+#endif
+}
+
+lconv *localeconv_l( locale_t &loc )
+{
+    __libcpp_locale_guard __current(loc);
+    lconv *lc = localeconv();
+    if (!lc)
+        return lc;
+    return loc.__store_lconv(lc);
+}
+size_t mbrlen_l( const char *__restrict s, size_t n,
+                 mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbrlen( s, n, ps );
+}
+size_t mbsrtowcs_l( wchar_t *__restrict dst, const char **__restrict src,
+                    size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbsrtowcs( dst, src, len, ps );
+}
+size_t wcrtomb_l( char *__restrict s, wchar_t wc, mbstate_t *__restrict ps,
+                  locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wcrtomb( s, wc, ps );
+}
+size_t mbrtowc_l( wchar_t *__restrict pwc, const char *__restrict s,
+                  size_t n, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbrtowc( pwc, s, n, ps );
+}
+size_t mbsnrtowcs_l( wchar_t *__restrict dst, const char **__restrict src,
+                     size_t nms, size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbsnrtowcs( dst, src, nms, len, ps );
+}
+size_t wcsnrtombs_l( char *__restrict dst, const wchar_t **__restrict src,
+                     size_t nwc, size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wcsnrtombs( dst, src, nwc, len, ps );
+}
+wint_t btowc_l( int c, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return btowc( c );
+}
+int wctob_l( wint_t c, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wctob( c );
+}
+
+int snprintf_l(char *ret, size_t n, locale_t loc, const char *format, ...)
+{
+    va_list ap;
+    va_start( ap, format );
+#if defined(_LIBCPP_MSVCRT)
+    // FIXME: Remove usage of internal CRT function and globals.
+    int result = __stdio_common_vsprintf(
+        _CRT_INTERNAL_LOCAL_PRINTF_OPTIONS | _CRT_INTERNAL_PRINTF_STANDARD_SNPRINTF_BEHAVIOR,
+        ret, n, format, loc, ap);
+#else
+    __libcpp_locale_guard __current(loc);
+    int result = vsnprintf( ret, n, format, ap );
+#endif
+    va_end(ap);
+    return result;
+}
+
+int asprintf_l( char **ret, locale_t loc, const char *format, ... )
+{
+    va_list ap;
+    va_start( ap, format );
+    int result = vasprintf_l( ret, loc, format, ap );
+    va_end(ap);
+    return result;
+}
+int vasprintf_l( char **ret, locale_t loc, const char *format, va_list ap )
+{
+    __libcpp_locale_guard __current(loc);
+    return __libcpp_vasprintf( ret, format, ap );
+}
+
+#if !defined(_LIBCPP_MSVCRT)
+float strtof_l(const char* nptr, char** endptr, locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strtof(nptr, endptr);
+}
+
+long double strtold_l(const char* nptr, char** endptr, locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strtold(nptr, endptr);
+}
+#endif
+
+#if defined(__MINGW32__) && __MSVCRT_VERSION__ < 0x0800
+size_t strftime_l(char *ret, size_t n, const char *format, const struct tm *tm,
+                  locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strftime(ret, n, format, tm);
+}
+#endif
diff --git a/lib/libcxx/src/support/win32/support.cpp b/lib/libcxx/src/support/win32/support.cpp
new file mode 100644
index 0000000000..d156e02e3e
--- /dev/null
+++ b/lib/libcxx/src/support/win32/support.cpp
@@ -0,0 +1,164 @@
+// -*- C++ -*-
+//===----------------------- support/win32/support.h ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdarg> // va_start, va_end
+#include <cstddef> // size_t
+#include <cstdlib> // malloc
+#include <cstdio>  // vsprintf, vsnprintf
+#include <cstring> // strcpy, wcsncpy
+#include <cwchar>  // mbstate_t
+
+
+// Like sprintf, but when return value >= 0 it returns
+// a pointer to a malloc'd string in *sptr.
+// If return >= 0, use free to delete *sptr.
+int __libcpp_vasprintf( char **sptr, const char *__restrict format, va_list ap )
+{
+    *sptr = NULL;
+    // Query the count required.
+    int count = _vsnprintf( NULL, 0, format, ap );
+    if (count < 0)
+        return count;
+    size_t buffer_size = static_cast<size_t>(count) + 1;
+    char* p = static_cast<char*>(malloc(buffer_size));
+    if ( ! p )
+        return -1;
+    // If we haven't used exactly what was required, something is wrong.
+    // Maybe bug in vsnprintf. Report the error and return.
+    if (_vsnprintf(p, buffer_size, format, ap) != count) {
+        free(p);
+        return -1;
+    }
+    // All good. This is returning memory to the caller not freeing it.
+    *sptr = p;
+    return count;
+}
+
+// Returns >= 0: the number of wide characters found in the
+// multi byte sequence src (of src_size_bytes), that fit in the buffer dst
+// (of max_dest_chars elements size). The count returned excludes the
+// null terminator. When dst is NULL, no characters are copied
+// and no "out" parameters are updated.
+// Returns (size_t) -1: an incomplete sequence encountered.
+// Leaves *src pointing the next character to convert or NULL
+// if a null character was converted from *src.
+size_t mbsnrtowcs( wchar_t *__restrict dst, const char **__restrict src,
+                   size_t src_size_bytes, size_t max_dest_chars, mbstate_t *__restrict ps )
+{
+    const size_t terminated_sequence = static_cast<size_t>(0);
+    //const size_t invalid_sequence = static_cast<size_t>(-1);
+    const size_t incomplete_sequence = static_cast< size_t>(-2);
+
+    size_t dest_converted = 0;
+    size_t source_converted = 0;
+    size_t source_remaining = src_size_bytes;
+    size_t result = 0;
+    bool have_result = false;
+
+    // If dst is null then max_dest_chars should be ignored according to the
+    // standard.  Setting max_dest_chars to a large value has this effect.
+    if (!dst)
+        max_dest_chars = static_cast<size_t>(-1);
+
+    while ( source_remaining ) {
+        if ( dst && dest_converted >= max_dest_chars )
+            break;
+        // Converts one multi byte character.
+        // if result > 0, it's the size in bytes of that character.
+        // othewise if result is zero it indicates the null character has been found.
+        // otherwise it's an error and errno may be set.
+        size_t char_size = mbrtowc( dst ? dst + dest_converted : NULL, *src + source_converted, source_remaining, ps );
+        // Don't do anything to change errno from here on.
+        if ( char_size > 0 ) {
+            source_remaining -= char_size;
+            source_converted += char_size;
+            ++dest_converted;
+            continue;
+        }
+        result = char_size;
+        have_result = true;
+        break;
+    }
+    if ( dst ) {
+        if ( have_result && result == terminated_sequence )
+            *src = NULL;
+        else
+            *src += source_converted;
+    }
+    if ( have_result && result != terminated_sequence && result != incomplete_sequence )
+        return static_cast<size_t>(-1);
+
+    return dest_converted;
+}
+
+// Converts max_source_chars from the wide character buffer pointer to by *src,
+// into the multi byte character sequence buffer stored at dst which must be
+// dst_size_bytes bytes in size.
+// Returns >= 0: the number of bytes in the sequence
+// converted from *src, excluding the null terminator.
+// Returns size_t(-1) if an error occurs, also sets errno.
+// If dst is NULL dst_size_bytes is ignored and no bytes are copied to dst
+// and no "out" parameters are updated.
+size_t wcsnrtombs( char *__restrict dst, const wchar_t **__restrict src,
+                   size_t max_source_chars, size_t dst_size_bytes, mbstate_t *__restrict ps )
+{
+    //const size_t invalid_sequence = static_cast<size_t>(-1);
+
+    size_t source_converted = 0;
+    size_t dest_converted = 0;
+    size_t dest_remaining = dst_size_bytes;
+    size_t char_size = 0;
+    const errno_t no_error = ( errno_t) 0;
+    errno_t result = ( errno_t ) 0;
+    bool have_result = false;
+    bool terminator_found = false;
+
+    // If dst is null then dst_size_bytes should be ignored according to the
+    // standard.  Setting dest_remaining to a large value has this effect.
+    if (!dst)
+        dest_remaining = static_cast<size_t>(-1);
+
+    while ( source_converted != max_source_chars ) {
+        if ( ! dest_remaining )
+            break;
+        wchar_t c = (*src)[source_converted];
+        if ( dst )
+            result = wcrtomb_s( &char_size, dst + dest_converted, dest_remaining, c, ps);
+        else
+            result = wcrtomb_s( &char_size, NULL, 0, c, ps);
+        // If result is zero there is no error and char_size contains the
+        // size of the multi-byte-sequence converted.
+        // Otherwise result indicates an errno type error.
+        if ( result == no_error ) {
+            if ( c == L'\0' ) {
+                terminator_found = true;
+                break;
+            }
+            ++source_converted;
+            if ( dst )
+                dest_remaining -= char_size;
+            dest_converted += char_size;
+            continue;
+        }
+        have_result = true;
+        break;
+    }
+    if ( dst ) {
+        if ( terminator_found )
+            *src = NULL;
+        else
+            *src = *src + source_converted;
+    }
+    if ( have_result && result != no_error ) {
+        errno = result;
+        return static_cast<size_t>(-1);
+    }
+
+    return dest_converted;
+}
diff --git a/lib/libcxx/src/support/win32/thread_win32.cpp b/lib/libcxx/src/support/win32/thread_win32.cpp
new file mode 100644
index 0000000000..83e7e9f6ce
--- /dev/null
+++ b/lib/libcxx/src/support/win32/thread_win32.cpp
@@ -0,0 +1,275 @@
+// -*- C++ -*-
+//===-------------------- support/win32/thread_win32.cpp ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__threading_support>
+#include <windows.h>
+#include <process.h>
+#include <fibersapi.h>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+static_assert(sizeof(__libcpp_mutex_t) == sizeof(SRWLOCK), "");
+static_assert(alignof(__libcpp_mutex_t) == alignof(SRWLOCK), "");
+
+static_assert(sizeof(__libcpp_recursive_mutex_t) == sizeof(CRITICAL_SECTION),
+              "");
+static_assert(alignof(__libcpp_recursive_mutex_t) == alignof(CRITICAL_SECTION),
+              "");
+
+static_assert(sizeof(__libcpp_condvar_t) == sizeof(CONDITION_VARIABLE), "");
+static_assert(alignof(__libcpp_condvar_t) == alignof(CONDITION_VARIABLE), "");
+
+static_assert(sizeof(__libcpp_exec_once_flag) == sizeof(INIT_ONCE), "");
+static_assert(alignof(__libcpp_exec_once_flag) == alignof(INIT_ONCE), "");
+
+static_assert(sizeof(__libcpp_thread_id) == sizeof(DWORD), "");
+static_assert(alignof(__libcpp_thread_id) == alignof(DWORD), "");
+
+static_assert(sizeof(__libcpp_thread_t) == sizeof(HANDLE), "");
+static_assert(alignof(__libcpp_thread_t) == alignof(HANDLE), "");
+
+static_assert(sizeof(__libcpp_tls_key) == sizeof(DWORD), "");
+static_assert(alignof(__libcpp_tls_key) == alignof(DWORD), "");
+
+// Mutex
+int __libcpp_recursive_mutex_init(__libcpp_recursive_mutex_t *__m)
+{
+  InitializeCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_recursive_mutex_lock(__libcpp_recursive_mutex_t *__m)
+{
+  EnterCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+bool __libcpp_recursive_mutex_trylock(__libcpp_recursive_mutex_t *__m)
+{
+  return TryEnterCriticalSection((LPCRITICAL_SECTION)__m) != 0;
+}
+
+int __libcpp_recursive_mutex_unlock(__libcpp_recursive_mutex_t *__m)
+{
+  LeaveCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_recursive_mutex_destroy(__libcpp_recursive_mutex_t *__m)
+{
+  DeleteCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_mutex_lock(__libcpp_mutex_t *__m)
+{
+  AcquireSRWLockExclusive((PSRWLOCK)__m);
+  return 0;
+}
+
+bool __libcpp_mutex_trylock(__libcpp_mutex_t *__m)
+{
+  return TryAcquireSRWLockExclusive((PSRWLOCK)__m) != 0;
+}
+
+int __libcpp_mutex_unlock(__libcpp_mutex_t *__m)
+{
+  ReleaseSRWLockExclusive((PSRWLOCK)__m);
+  return 0;
+}
+
+int __libcpp_mutex_destroy(__libcpp_mutex_t *__m)
+{
+  static_cast<void>(__m);
+  return 0;
+}
+
+// Condition Variable
+int __libcpp_condvar_signal(__libcpp_condvar_t *__cv)
+{
+  WakeConditionVariable((PCONDITION_VARIABLE)__cv);
+  return 0;
+}
+
+int __libcpp_condvar_broadcast(__libcpp_condvar_t *__cv)
+{
+  WakeAllConditionVariable((PCONDITION_VARIABLE)__cv);
+  return 0;
+}
+
+int __libcpp_condvar_wait(__libcpp_condvar_t *__cv, __libcpp_mutex_t *__m)
+{
+  SleepConditionVariableSRW((PCONDITION_VARIABLE)__cv, (PSRWLOCK)__m, INFINITE, 0);
+  return 0;
+}
+
+int __libcpp_condvar_timedwait(__libcpp_condvar_t *__cv, __libcpp_mutex_t *__m,
+                               __libcpp_timespec_t *__ts)
+{
+  using namespace _VSTD::chrono;
+
+  auto duration = seconds(__ts->tv_sec) + nanoseconds(__ts->tv_nsec);
+  auto abstime =
+      system_clock::time_point(duration_cast<system_clock::duration>(duration));
+  auto timeout_ms = duration_cast<milliseconds>(abstime - system_clock::now());
+
+  if (!SleepConditionVariableSRW((PCONDITION_VARIABLE)__cv, (PSRWLOCK)__m,
+                                 timeout_ms.count() > 0 ? timeout_ms.count()
+                                                        : 0,
+                                 0))
+    {
+      auto __ec = GetLastError();
+      return __ec == ERROR_TIMEOUT ? ETIMEDOUT : __ec;
+    }
+  return 0;
+}
+
+int __libcpp_condvar_destroy(__libcpp_condvar_t *__cv)
+{
+  static_cast<void>(__cv);
+  return 0;
+}
+
+// Execute Once
+static inline _LIBCPP_INLINE_VISIBILITY BOOL CALLBACK
+__libcpp_init_once_execute_once_thunk(PINIT_ONCE __init_once, PVOID __parameter,
+                                      PVOID *__context)
+{
+  static_cast<void>(__init_once);
+  static_cast<void>(__context);
+
+  void (*init_routine)(void) = reinterpret_cast<void (*)(void)>(__parameter);
+  init_routine();
+  return TRUE;
+}
+
+int __libcpp_execute_once(__libcpp_exec_once_flag *__flag,
+                          void (*__init_routine)(void))
+{
+  if (!InitOnceExecuteOnce((PINIT_ONCE)__flag, __libcpp_init_once_execute_once_thunk,
+                           reinterpret_cast<void *>(__init_routine), NULL))
+    return GetLastError();
+  return 0;
+}
+
+// Thread ID
+bool __libcpp_thread_id_equal(__libcpp_thread_id __lhs,
+                              __libcpp_thread_id __rhs)
+{
+  return __lhs == __rhs;
+}
+
+bool __libcpp_thread_id_less(__libcpp_thread_id __lhs, __libcpp_thread_id __rhs)
+{
+  return __lhs < __rhs;
+}
+
+// Thread
+struct __libcpp_beginthreadex_thunk_data
+{
+  void *(*__func)(void *);
+  void *__arg;
+};
+
+static inline _LIBCPP_INLINE_VISIBILITY unsigned WINAPI
+__libcpp_beginthreadex_thunk(void *__raw_data)
+{
+  auto *__data =
+      static_cast<__libcpp_beginthreadex_thunk_data *>(__raw_data);
+  auto *__func = __data->__func;
+  void *__arg = __data->__arg;
+  delete __data;
+  return static_cast<unsigned>(reinterpret_cast<uintptr_t>(__func(__arg)));
+}
+
+bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
+  return *__t == 0;
+}
+
+int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
+                           void *__arg)
+{
+  auto *__data = new __libcpp_beginthreadex_thunk_data;
+  __data->__func = __func;
+  __data->__arg = __arg;
+
+  *__t = reinterpret_cast<HANDLE>(_beginthreadex(nullptr, 0,
+                                                 __libcpp_beginthreadex_thunk,
+                                                 __data, 0, nullptr));
+
+  if (*__t)
+    return 0;
+  return GetLastError();
+}
+
+__libcpp_thread_id __libcpp_thread_get_current_id()
+{
+  return GetCurrentThreadId();
+}
+
+__libcpp_thread_id __libcpp_thread_get_id(const __libcpp_thread_t *__t)
+{
+  return GetThreadId(*__t);
+}
+
+int __libcpp_thread_join(__libcpp_thread_t *__t)
+{
+  if (WaitForSingleObjectEx(*__t, INFINITE, FALSE) == WAIT_FAILED)
+    return GetLastError();
+  if (!CloseHandle(*__t))
+    return GetLastError();
+  return 0;
+}
+
+int __libcpp_thread_detach(__libcpp_thread_t *__t)
+{
+  if (!CloseHandle(*__t))
+    return GetLastError();
+  return 0;
+}
+
+void __libcpp_thread_yield()
+{
+  SwitchToThread();
+}
+
+void __libcpp_thread_sleep_for(const chrono::nanoseconds& __ns)
+{
+  using namespace chrono;
+  // round-up to the nearest milisecond
+  milliseconds __ms =
+      duration_cast<milliseconds>(__ns + chrono::nanoseconds(999999));
+  // FIXME(compnerd) this should be an alertable sleep (WFSO or SleepEx)
+  Sleep(__ms.count());
+}
+
+// Thread Local Storage
+int __libcpp_tls_create(__libcpp_tls_key* __key,
+                        void(_LIBCPP_TLS_DESTRUCTOR_CC* __at_exit)(void*))
+{
+  DWORD index = FlsAlloc(__at_exit);
+  if (index == FLS_OUT_OF_INDEXES)
+    return GetLastError();
+  *__key = index;
+  return 0;
+}
+
+void *__libcpp_tls_get(__libcpp_tls_key __key)
+{
+  return FlsGetValue(__key);
+}
+
+int __libcpp_tls_set(__libcpp_tls_key __key, void *__p)
+{
+  if (!FlsSetValue(__key, __p))
+    return GetLastError();
+  return 0;
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/system_error.cpp b/lib/libcxx/src/system_error.cpp
new file mode 100644
index 0000000000..9ddf7bcbe0
--- /dev/null
+++ b/lib/libcxx/src/system_error.cpp
@@ -0,0 +1,295 @@
+//===---------------------- system_error.cpp ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+
+#include "system_error"
+
+#include "include/config_elast.h"
+#include "cerrno"
+#include "cstring"
+#include "cstdio"
+#include "cstdlib"
+#include "string"
+#include "string.h"
+#include "__debug"
+
+#if defined(__ANDROID__)
+#include <android/api-level.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// class error_category
+
+#if defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
+error_category::error_category() _NOEXCEPT
+{
+}
+#endif
+
+error_category::~error_category() _NOEXCEPT
+{
+}
+
+error_condition
+error_category::default_error_condition(int ev) const _NOEXCEPT
+{
+    return error_condition(ev, *this);
+}
+
+bool
+error_category::equivalent(int code, const error_condition& condition) const _NOEXCEPT
+{
+    return default_error_condition(code) == condition;
+}
+
+bool
+error_category::equivalent(const error_code& code, int condition) const _NOEXCEPT
+{
+    return *this == code.category() && code.value() == condition;
+}
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+namespace {
+
+//  GLIBC also uses 1024 as the maximum buffer size internally.
+constexpr size_t strerror_buff_size = 1024;
+
+string do_strerror_r(int ev);
+
+#if defined(_LIBCPP_MSVCRT_LIKE)
+string do_strerror_r(int ev) {
+  char buffer[strerror_buff_size];
+  if (::strerror_s(buffer, strerror_buff_size, ev) == 0)
+    return string(buffer);
+  std::snprintf(buffer, strerror_buff_size, "unknown error %d", ev);
+  return string(buffer);
+}
+#else
+
+// Only one of the two following functions will be used, depending on
+// the return type of strerror_r:
+
+// For the GNU variant, a char* return value:
+__attribute__((unused)) const char *
+handle_strerror_r_return(char *strerror_return, char *buffer) {
+  // GNU always returns a string pointer in its return value. The
+  // string might point to either the input buffer, or a static
+  // buffer, but we don't care which.
+  return strerror_return;
+}
+
+// For the POSIX variant: an int return value.
+__attribute__((unused)) const char *
+handle_strerror_r_return(int strerror_return, char *buffer) {
+  // The POSIX variant either:
+  // - fills in the provided buffer and returns 0
+  // - returns a positive error value, or
+  // - returns -1 and fills in errno with an error value.
+  if (strerror_return == 0)
+    return buffer;
+
+  // Only handle EINVAL. Other errors abort.
+  int new_errno = strerror_return == -1 ? errno : strerror_return;
+  if (new_errno == EINVAL)
+    return "";
+
+  _LIBCPP_ASSERT(new_errno == ERANGE, "unexpected error from ::strerror_r");
+  // FIXME maybe? 'strerror_buff_size' is likely to exceed the
+  // maximum error size so ERANGE shouldn't be returned.
+  std::abort();
+}
+
+// This function handles both GNU and POSIX variants, dispatching to
+// one of the two above functions.
+string do_strerror_r(int ev) {
+    char buffer[strerror_buff_size];
+    // Preserve errno around the call. (The C++ standard requires that
+    // system_error functions not modify errno).
+    const int old_errno = errno;
+    const char *error_message = handle_strerror_r_return(
+        ::strerror_r(ev, buffer, strerror_buff_size), buffer);
+    // If we didn't get any message, print one now.
+    if (!error_message[0]) {
+      std::snprintf(buffer, strerror_buff_size, "Unknown error %d", ev);
+      error_message = buffer;
+    }
+    errno = old_errno;
+    return string(error_message);
+}
+#endif
+} // end namespace
+#endif
+
+string
+__do_message::message(int ev) const
+{
+#if defined(_LIBCPP_HAS_NO_THREADS)
+    return string(::strerror(ev));
+#else
+    return do_strerror_r(ev);
+#endif
+}
+
+class _LIBCPP_HIDDEN __generic_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const _NOEXCEPT;
+    virtual string message(int ev) const;
+};
+
+const char*
+__generic_error_category::name() const _NOEXCEPT
+{
+    return "generic";
+}
+
+string
+__generic_error_category::message(int ev) const
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return string("unspecified generic_category error");
+#endif  // _LIBCPP_ELAST
+    return __do_message::message(ev);
+}
+
+const error_category&
+generic_category() _NOEXCEPT
+{
+    static __generic_error_category s;
+    return s;
+}
+
+class _LIBCPP_HIDDEN __system_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const _NOEXCEPT;
+    virtual string message(int ev) const;
+    virtual error_condition default_error_condition(int ev) const _NOEXCEPT;
+};
+
+const char*
+__system_error_category::name() const _NOEXCEPT
+{
+    return "system";
+}
+
+string
+__system_error_category::message(int ev) const
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return string("unspecified system_category error");
+#endif  // _LIBCPP_ELAST
+    return __do_message::message(ev);
+}
+
+error_condition
+__system_error_category::default_error_condition(int ev) const _NOEXCEPT
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return error_condition(ev, system_category());
+#endif  // _LIBCPP_ELAST
+    return error_condition(ev, generic_category());
+}
+
+const error_category&
+system_category() _NOEXCEPT
+{
+    static __system_error_category s;
+    return s;
+}
+
+// error_condition
+
+string
+error_condition::message() const
+{
+    return __cat_->message(__val_);
+}
+
+// error_code
+
+string
+error_code::message() const
+{
+    return __cat_->message(__val_);
+}
+
+// system_error
+
+string
+system_error::__init(const error_code& ec, string what_arg)
+{
+    if (ec)
+    {
+        if (!what_arg.empty())
+            what_arg += ": ";
+        what_arg += ec.message();
+    }
+    return what_arg;
+}
+
+system_error::system_error(error_code ec, const string& what_arg)
+    : runtime_error(__init(ec, what_arg)),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(error_code ec, const char* what_arg)
+    : runtime_error(__init(ec, what_arg)),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(error_code ec)
+    : runtime_error(__init(ec, "")),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat, const string& what_arg)
+    : runtime_error(__init(error_code(ev, ecat), what_arg)),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat, const char* what_arg)
+    : runtime_error(__init(error_code(ev, ecat), what_arg)),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat)
+    : runtime_error(__init(error_code(ev, ecat), "")),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::~system_error() _NOEXCEPT
+{
+}
+
+void
+__throw_system_error(int ev, const char* what_arg)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw system_error(error_code(ev, system_category()), what_arg);
+#else
+    (void)ev;
+    (void)what_arg;
+    _VSTD::abort();
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/thread.cpp b/lib/libcxx/src/thread.cpp
new file mode 100644
index 0000000000..c0bc1cbbbb
--- /dev/null
+++ b/lib/libcxx/src/thread.cpp
@@ -0,0 +1,225 @@
+//===------------------------- thread.cpp----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__config"
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include "thread"
+#include "exception"
+#include "vector"
+#include "future"
+#include "limits"
+#include <sys/types.h>
+
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+# include <sys/param.h>
+# if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) || defined(__APPLE__)
+#   include <sys/sysctl.h>
+# endif
+#endif // defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__) || defined(__wasi__)
+# include <unistd.h>
+#endif // defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__) || defined(__wasi__)
+
+#if defined(__NetBSD__)
+#pragma weak pthread_create // Do not create libpthread dependency
+#endif
+
+#if defined(_LIBCPP_WIN32API)
+#include <windows.h>
+#endif
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+thread::~thread()
+{
+    if (!__libcpp_thread_isnull(&__t_))
+        terminate();
+}
+
+void
+thread::join()
+{
+    int ec = EINVAL;
+    if (!__libcpp_thread_isnull(&__t_))
+    {
+        ec = __libcpp_thread_join(&__t_);
+        if (ec == 0)
+            __t_ = _LIBCPP_NULL_THREAD;
+    }
+
+    if (ec)
+        __throw_system_error(ec, "thread::join failed");
+}
+
+void
+thread::detach()
+{
+    int ec = EINVAL;
+    if (!__libcpp_thread_isnull(&__t_))
+    {
+        ec = __libcpp_thread_detach(&__t_);
+        if (ec == 0)
+            __t_ = _LIBCPP_NULL_THREAD;
+    }
+
+    if (ec)
+        __throw_system_error(ec, "thread::detach failed");
+}
+
+unsigned
+thread::hardware_concurrency() _NOEXCEPT
+{
+#if defined(CTL_HW) && defined(HW_NCPU)
+    unsigned n;
+    int mib[2] = {CTL_HW, HW_NCPU};
+    std::size_t s = sizeof(n);
+    sysctl(mib, 2, &n, &s, 0, 0);
+    return n;
+#elif defined(_SC_NPROCESSORS_ONLN)
+    long result = sysconf(_SC_NPROCESSORS_ONLN);
+    // sysconf returns -1 if the name is invalid, the option does not exist or
+    // does not have a definite limit.
+    // if sysconf returns some other negative number, we have no idea
+    // what is going on. Default to something safe.
+    if (result < 0)
+        return 0;
+    return static_cast<unsigned>(result);
+#elif defined(_LIBCPP_WIN32API)
+    SYSTEM_INFO info;
+    GetSystemInfo(&info);
+    return info.dwNumberOfProcessors;
+#else  // defined(CTL_HW) && defined(HW_NCPU)
+    // TODO: grovel through /proc or check cpuid on x86 and similar
+    // instructions on other architectures.
+#   if defined(_LIBCPP_WARNING)
+        _LIBCPP_WARNING("hardware_concurrency not yet implemented")
+#   else
+#       warning hardware_concurrency not yet implemented
+#   endif
+    return 0;  // Means not computable [thread.thread.static]
+#endif  // defined(CTL_HW) && defined(HW_NCPU)
+}
+
+namespace this_thread
+{
+
+void
+sleep_for(const chrono::nanoseconds& ns)
+{
+    if (ns > chrono::nanoseconds::zero())
+    {
+        __libcpp_thread_sleep_for(ns);
+    }
+}
+
+}  // this_thread
+
+__thread_specific_ptr<__thread_struct>&
+__thread_local_data()
+{
+    static __thread_specific_ptr<__thread_struct> __p;
+    return __p;
+}
+
+// __thread_struct_imp
+
+template <class T>
+class _LIBCPP_HIDDEN __hidden_allocator
+{
+public:
+    typedef T  value_type;
+
+    T* allocate(size_t __n)
+        {return static_cast<T*>(::operator new(__n * sizeof(T)));}
+    void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));}
+
+    size_t max_size() const {return size_t(~0) / sizeof(T);}
+};
+
+class _LIBCPP_HIDDEN __thread_struct_imp
+{
+    typedef vector<__assoc_sub_state*,
+                          __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
+    typedef vector<pair<condition_variable*, mutex*>,
+               __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
+
+    _AsyncStates async_states_;
+    _Notify notify_;
+
+    __thread_struct_imp(const __thread_struct_imp&);
+    __thread_struct_imp& operator=(const __thread_struct_imp&);
+public:
+    __thread_struct_imp() {}
+    ~__thread_struct_imp();
+
+    void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
+    void __make_ready_at_thread_exit(__assoc_sub_state* __s);
+};
+
+__thread_struct_imp::~__thread_struct_imp()
+{
+    for (_Notify::iterator i = notify_.begin(), e = notify_.end();
+            i != e; ++i)
+    {
+        i->second->unlock();
+        i->first->notify_all();
+    }
+    for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end();
+            i != e; ++i)
+    {
+        (*i)->__make_ready();
+        (*i)->__release_shared();
+    }
+}
+
+void
+__thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
+{
+    notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
+}
+
+void
+__thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s)
+{
+    async_states_.push_back(__s);
+    __s->__add_shared();
+}
+
+// __thread_struct
+
+__thread_struct::__thread_struct()
+    : __p_(new __thread_struct_imp)
+{
+}
+
+__thread_struct::~__thread_struct()
+{
+    delete __p_;
+}
+
+void
+__thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
+{
+    __p_->notify_all_at_thread_exit(cv, m);
+}
+
+void
+__thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s)
+{
+    __p_->__make_ready_at_thread_exit(__s);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS
diff --git a/lib/libcxx/src/typeinfo.cpp b/lib/libcxx/src/typeinfo.cpp
new file mode 100644
index 0000000000..49a07ef7da
--- /dev/null
+++ b/lib/libcxx/src/typeinfo.cpp
@@ -0,0 +1,57 @@
+//===------------------------- typeinfo.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "typeinfo"
+
+#if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_ABI_VCRUNTIME)
+#include <string.h>
+
+int std::type_info::__compare(const type_info &__rhs) const _NOEXCEPT {
+  if (&__data == &__rhs.__data)
+    return 0;
+  return strcmp(&__data.__decorated_name[1], &__rhs.__data.__decorated_name[1]);
+}
+
+const char *std::type_info::name() const _NOEXCEPT {
+  // TODO(compnerd) cache demangled &__data.__decorated_name[1]
+  return &__data.__decorated_name[1];
+}
+
+size_t std::type_info::hash_code() const _NOEXCEPT {
+#if defined(_WIN64)
+  constexpr size_t fnv_offset_basis = 14695981039346656037ull;
+  constexpr size_t fnv_prime = 10995116282110ull;
+#else
+  constexpr size_t fnv_offset_basis = 2166136261ull;
+  constexpr size_t fnv_prime = 16777619ull;
+#endif
+
+  size_t value = fnv_offset_basis;
+  for (const char* c = &__data.__decorated_name[1]; *c; ++c) {
+    value ^= static_cast<size_t>(static_cast<unsigned char>(*c));
+    value *= fnv_prime;
+  }
+
+#if defined(_WIN64)
+  value ^= value >> 32;
+#endif
+
+  return value;
+}
+#endif // _LIBCPP_ABI_MICROSOFT
+
+// FIXME: Remove the _LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY configuration.
+#if (!defined(LIBCXX_BUILDING_LIBCXXABI) &&               \
+     !defined(LIBCXXRT) &&                                \
+     !defined(__GLIBCXX__) &&                             \
+     !defined(_LIBCPP_ABI_VCRUNTIME)) ||                  \
+    defined(_LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY)
+std::type_info::~type_info()
+{
+}
+#endif
diff --git a/lib/libcxx/src/utility.cpp b/lib/libcxx/src/utility.cpp
new file mode 100644
index 0000000000..6a690dc287
--- /dev/null
+++ b/lib/libcxx/src/utility.cpp
@@ -0,0 +1,15 @@
+//===------------------------ utility.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "utility"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+const piecewise_construct_t piecewise_construct{};
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/valarray.cpp b/lib/libcxx/src/valarray.cpp
new file mode 100644
index 0000000000..64d26583c7
--- /dev/null
+++ b/lib/libcxx/src/valarray.cpp
@@ -0,0 +1,57 @@
+//===------------------------ valarray.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "valarray"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// These two symbols are part of the v1 ABI but not part of the >=v2 ABI.
+#if _LIBCPP_ABI_VERSION == 1
+template _LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t);
+template _LIBCPP_FUNC_VIS valarray<size_t>::~valarray();
+#endif
+
+template void valarray<size_t>::resize(size_t, size_t);
+
+void
+gslice::__init(size_t __start)
+{
+    valarray<size_t> __indices(__size_.size());
+    size_t __k = __size_.size() != 0;
+    for (size_t __i = 0; __i < __size_.size(); ++__i)
+        __k *= __size_[__i];
+    __1d_.resize(__k);
+    if (__1d_.size())
+    {
+        __k = 0;
+        __1d_[__k] = __start;
+        while (true)
+        {
+            size_t __i = __indices.size() - 1;
+            while (true)
+            {
+                if (++__indices[__i] < __size_[__i])
+                {
+                    ++__k;
+                    __1d_[__k] = __1d_[__k-1] + __stride_[__i];
+                    for (size_t __j = __i + 1; __j != __indices.size(); ++__j)
+                        __1d_[__k] -= __stride_[__j] * (__size_[__j] - 1);
+                    break;
+                }
+                else
+                {
+                    if (__i == 0)
+                        return;
+                    __indices[__i--] = 0;
+                }
+            }
+        }
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxx/src/variant.cpp b/lib/libcxx/src/variant.cpp
new file mode 100644
index 0000000000..1fe70a1809
--- /dev/null
+++ b/lib/libcxx/src/variant.cpp
@@ -0,0 +1,17 @@
+//===------------------------ variant.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "variant"
+
+namespace std {
+
+const char* bad_variant_access::what() const noexcept {
+  return "bad_variant_access";
+}
+
+}  // namespace std
diff --git a/lib/libcxx/src/vector.cpp b/lib/libcxx/src/vector.cpp
new file mode 100644
index 0000000000..3b65e558fd
--- /dev/null
+++ b/lib/libcxx/src/vector.cpp
@@ -0,0 +1,15 @@
+//===------------------------- vector.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "vector"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __vector_base_common<true>;
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/lib/libcxxabi/LICENSE.TXT b/lib/libcxxabi/LICENSE.TXT
new file mode 100644
index 0000000000..b75c0441bc
--- /dev/null
+++ b/lib/libcxxabi/LICENSE.TXT
@@ -0,0 +1,311 @@
+==============================================================================
+The LLVM Project is under the Apache License v2.0 with LLVM Exceptions:
+==============================================================================
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+    TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+    1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
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+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
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+      direction or management of such entity, whether by contract or
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+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
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+      including but not limited to software source code, documentation
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+
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+      "Work" shall mean the work of authorship, whether in Source or
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+      "Derivative Works" shall mean any work, whether in Source or Object
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+      "Contribution" shall mean any work of authorship, including
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+      You may add Your own copyright statement to Your modifications and
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+
+In addition, if you combine or link compiled forms of this Software with
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+
+==============================================================================
+Software from third parties included in the LLVM Project:
+==============================================================================
+The LLVM Project contains third party software which is under different license
+terms. All such code will be identified clearly using at least one of two
+mechanisms:
+1) It will be in a separate directory tree with its own `LICENSE.txt` or
+   `LICENSE` file at the top containing the specific license and restrictions
+   which apply to that software, or
+2) It will contain specific license and restriction terms at the top of every
+   file.
+
+==============================================================================
+Legacy LLVM License (https://llvm.org/docs/DeveloperPolicy.html#legacy):
+==============================================================================
+
+The libc++abi library is dual licensed under both the University of Illinois
+"BSD-Like" license and the MIT license.  As a user of this code you may choose
+to use it under either license.  As a contributor, you agree to allow your code
+to be used under both.
+
+Full text of the relevant licenses is included below.
+
+==============================================================================
+
+University of Illinois/NCSA
+Open Source License
+
+Copyright (c) 2009-2019 by the contributors listed in CREDITS.TXT
+
+All rights reserved.
+
+Developed by:
+
+    LLVM Team
+
+    University of Illinois at Urbana-Champaign
+
+    http://llvm.org
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal with
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimers.
+
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimers in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the names of the LLVM Team, University of Illinois at
+      Urbana-Champaign, nor the names of its contributors may be used to
+      endorse or promote products derived from this Software without specific
+      prior written permission.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+SOFTWARE.
+
+==============================================================================
+
+Copyright (c) 2009-2014 by the contributors listed in CREDITS.TXT
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/lib/libcxxabi/include/__cxxabi_config.h b/lib/libcxxabi/include/__cxxabi_config.h
new file mode 100644
index 0000000000..cbbb1c10c1
--- /dev/null
+++ b/lib/libcxxabi/include/__cxxabi_config.h
@@ -0,0 +1,79 @@
+//===-------------------------- __cxxabi_config.h -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ____CXXABI_CONFIG_H
+#define ____CXXABI_CONFIG_H
+
+#if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) &&                 \
+    !defined(__ARM_DWARF_EH__)
+#define _LIBCXXABI_ARM_EHABI
+#endif
+
+#if !defined(__has_attribute)
+#define __has_attribute(_attribute_) 0
+#endif
+
+#if defined(_WIN32)
+ #if defined(_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
+  #define _LIBCXXABI_HIDDEN
+  #define _LIBCXXABI_DATA_VIS
+  #define _LIBCXXABI_FUNC_VIS
+  #define _LIBCXXABI_TYPE_VIS
+ #elif defined(_LIBCXXABI_BUILDING_LIBRARY)
+  #define _LIBCXXABI_HIDDEN
+  #define _LIBCXXABI_DATA_VIS __declspec(dllexport)
+  #define _LIBCXXABI_FUNC_VIS __declspec(dllexport)
+  #define _LIBCXXABI_TYPE_VIS __declspec(dllexport)
+ #else
+  #define _LIBCXXABI_HIDDEN
+  #define _LIBCXXABI_DATA_VIS __declspec(dllimport)
+  #define _LIBCXXABI_FUNC_VIS __declspec(dllimport)
+  #define _LIBCXXABI_TYPE_VIS __declspec(dllimport)
+ #endif
+#else
+ #if !defined(_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
+  #define _LIBCXXABI_HIDDEN __attribute__((__visibility__("hidden")))
+  #define _LIBCXXABI_DATA_VIS __attribute__((__visibility__("default")))
+  #define _LIBCXXABI_FUNC_VIS __attribute__((__visibility__("default")))
+  #if __has_attribute(__type_visibility__)
+   #define _LIBCXXABI_TYPE_VIS __attribute__((__type_visibility__("default")))
+  #else
+   #define _LIBCXXABI_TYPE_VIS __attribute__((__visibility__("default")))
+  #endif
+ #else
+  #define _LIBCXXABI_HIDDEN
+  #define _LIBCXXABI_DATA_VIS
+  #define _LIBCXXABI_FUNC_VIS
+  #define _LIBCXXABI_TYPE_VIS
+ #endif
+#endif
+
+#if defined(_WIN32)
+#define _LIBCXXABI_WEAK
+#else
+#define _LIBCXXABI_WEAK __attribute__((__weak__))
+#endif
+
+#if defined(__clang__)
+#define _LIBCXXABI_COMPILER_CLANG
+#elif defined(__GNUC__)
+#define _LIBCXXABI_COMPILER_GCC
+#endif
+
+#if __has_attribute(__no_sanitize__) && defined(_LIBCXXABI_COMPILER_CLANG)
+#define _LIBCXXABI_NO_CFI __attribute__((__no_sanitize__("cfi")))
+#else
+#define _LIBCXXABI_NO_CFI
+#endif
+
+// wasm32 follows the arm32 ABI convention of using 32-bit guard.
+#if defined(__arm__) || defined(__wasm32__)
+#  define _LIBCXXABI_GUARD_ABI_ARM
+#endif
+
+#endif // ____CXXABI_CONFIG_H
diff --git a/lib/libcxxabi/include/cxxabi.h b/lib/libcxxabi/include/cxxabi.h
new file mode 100644
index 0000000000..d21d3e1e23
--- /dev/null
+++ b/lib/libcxxabi/include/cxxabi.h
@@ -0,0 +1,176 @@
+//===--------------------------- cxxabi.h ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __CXXABI_H
+#define __CXXABI_H
+
+/*
+ * This header provides the interface to the C++ ABI as defined at:
+ *       https://itanium-cxx-abi.github.io/cxx-abi/
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <__cxxabi_config.h>
+
+#define _LIBCPPABI_VERSION 1002
+#define _LIBCXXABI_NORETURN  __attribute__((noreturn))
+
+#ifdef __cplusplus
+
+namespace std {
+#if defined(_WIN32)
+class _LIBCXXABI_TYPE_VIS type_info; // forward declaration
+#else
+class type_info; // forward declaration
+#endif
+}
+
+
+// runtime routines use C calling conventions, but are in __cxxabiv1 namespace
+namespace __cxxabiv1 {
+extern "C"  {
+
+// 2.4.2 Allocating the Exception Object
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_allocate_exception(size_t thrown_size) throw();
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_free_exception(void *thrown_exception) throw();
+
+// 2.4.3 Throwing the Exception Object
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void
+__cxa_throw(void *thrown_exception, std::type_info *tinfo,
+            void (*dest)(void *));
+
+// 2.5.3 Exception Handlers
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_get_exception_ptr(void *exceptionObject) throw();
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_begin_catch(void *exceptionObject) throw();
+extern _LIBCXXABI_FUNC_VIS void __cxa_end_catch();
+#if defined(_LIBCXXABI_ARM_EHABI)
+extern _LIBCXXABI_FUNC_VIS bool
+__cxa_begin_cleanup(void *exceptionObject) throw();
+extern _LIBCXXABI_FUNC_VIS void __cxa_end_cleanup();
+#endif
+extern _LIBCXXABI_FUNC_VIS std::type_info *__cxa_current_exception_type();
+
+// 2.5.4 Rethrowing Exceptions
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_rethrow();
+
+// 2.6 Auxiliary Runtime APIs
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_bad_cast(void);
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_bad_typeid(void);
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void
+__cxa_throw_bad_array_new_length(void);
+
+// 3.2.6 Pure Virtual Function API
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_pure_virtual(void);
+
+// 3.2.7 Deleted Virtual Function API
+extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_deleted_virtual(void);
+
+// 3.3.2 One-time Construction API
+#if defined(_LIBCXXABI_GUARD_ABI_ARM)
+extern _LIBCXXABI_FUNC_VIS int __cxa_guard_acquire(uint32_t *);
+extern _LIBCXXABI_FUNC_VIS void __cxa_guard_release(uint32_t *);
+extern _LIBCXXABI_FUNC_VIS void __cxa_guard_abort(uint32_t *);
+#else
+extern _LIBCXXABI_FUNC_VIS int __cxa_guard_acquire(uint64_t *);
+extern _LIBCXXABI_FUNC_VIS void __cxa_guard_release(uint64_t *);
+extern _LIBCXXABI_FUNC_VIS void __cxa_guard_abort(uint64_t *);
+#endif
+
+// 3.3.3 Array Construction and Destruction API
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new(size_t element_count, size_t element_size, size_t padding_size,
+              void (*constructor)(void *), void (*destructor)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new2(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new3(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *, size_t));
+
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_vec_ctor(void *array_address, size_t element_count, size_t element_size,
+               void (*constructor)(void *), void (*destructor)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void __cxa_vec_dtor(void *array_address,
+                                               size_t element_count,
+                                               size_t element_size,
+                                               void (*destructor)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void __cxa_vec_cleanup(void *array_address,
+                                                  size_t element_count,
+                                                  size_t element_size,
+                                                  void (*destructor)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void __cxa_vec_delete(void *array_address,
+                                                 size_t element_size,
+                                                 size_t padding_size,
+                                                 void (*destructor)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete2(void *array_address, size_t element_size, size_t padding_size,
+                  void (*destructor)(void *), void (*dealloc)(void *));
+
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete3(void *__array_address, size_t element_size,
+                  size_t padding_size, void (*destructor)(void *),
+                  void (*dealloc)(void *, size_t));
+
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_vec_cctor(void *dest_array, void *src_array, size_t element_count,
+                size_t element_size, void (*constructor)(void *, void *),
+                void (*destructor)(void *));
+
+// 3.3.5.3 Runtime API
+extern _LIBCXXABI_FUNC_VIS int __cxa_atexit(void (*f)(void *), void *p,
+                                            void *d);
+extern _LIBCXXABI_FUNC_VIS int __cxa_finalize(void *);
+
+// 3.4 Demangler API
+extern _LIBCXXABI_FUNC_VIS char *__cxa_demangle(const char *mangled_name,
+                                                char *output_buffer,
+                                                size_t *length, int *status);
+
+// Apple additions to support C++ 0x exception_ptr class
+// These are primitives to wrap a smart pointer around an exception object
+extern _LIBCXXABI_FUNC_VIS void *__cxa_current_primary_exception() throw();
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_rethrow_primary_exception(void *primary_exception);
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_increment_exception_refcount(void *primary_exception) throw();
+extern _LIBCXXABI_FUNC_VIS void
+__cxa_decrement_exception_refcount(void *primary_exception) throw();
+
+// Apple extension to support std::uncaught_exception()
+extern _LIBCXXABI_FUNC_VIS bool __cxa_uncaught_exception() throw();
+extern _LIBCXXABI_FUNC_VIS unsigned int __cxa_uncaught_exceptions() throw();
+
+#if defined(__linux__) || defined(__Fuchsia__)
+// Linux and Fuchsia TLS support. Not yet an official part of the Itanium ABI.
+// https://sourceware.org/glibc/wiki/Destructor%20support%20for%20thread_local%20variables
+extern _LIBCXXABI_FUNC_VIS int __cxa_thread_atexit(void (*)(void *), void *,
+                                                   void *) throw();
+#endif
+
+} // extern "C"
+} // namespace __cxxabiv1
+
+namespace abi = __cxxabiv1;
+
+#endif // __cplusplus
+
+#endif // __CXXABI_H
diff --git a/lib/libcxxabi/src/abort_message.cpp b/lib/libcxxabi/src/abort_message.cpp
new file mode 100644
index 0000000000..d556af1c90
--- /dev/null
+++ b/lib/libcxxabi/src/abort_message.cpp
@@ -0,0 +1,77 @@
+//===------------------------- abort_message.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include "abort_message.h"
+
+#ifdef __BIONIC__
+#include <android/api-level.h>
+#if __ANDROID_API__ >= 21
+#include <syslog.h>
+extern "C" void android_set_abort_message(const char* msg);
+#else
+#include <assert.h>
+#endif // __ANDROID_API__ >= 21
+#endif // __BIONIC__
+
+#ifdef __APPLE__
+#   if defined(__has_include) && __has_include(<CrashReporterClient.h>)
+#       define HAVE_CRASHREPORTERCLIENT_H
+#       include <CrashReporterClient.h>
+#   endif
+#endif
+
+void abort_message(const char* format, ...)
+{
+    // write message to stderr
+#if !defined(NDEBUG) || !defined(LIBCXXABI_BAREMETAL)
+#ifdef __APPLE__
+    fprintf(stderr, "libc++abi.dylib: ");
+#endif
+    va_list list;
+    va_start(list, format);
+    vfprintf(stderr, format, list);
+    va_end(list);
+    fprintf(stderr, "\n");
+#endif
+
+#if defined(__APPLE__) && defined(HAVE_CRASHREPORTERCLIENT_H)
+    // record message in crash report
+    char* buffer;
+    va_list list2;
+    va_start(list2, format);
+    vasprintf(&buffer, format, list2);
+    va_end(list2);
+    CRSetCrashLogMessage(buffer);
+#elif defined(__BIONIC__)
+    char* buffer;
+    va_list list2;
+    va_start(list2, format);
+    vasprintf(&buffer, format, list2);
+    va_end(list2);
+
+#if __ANDROID_API__ >= 21
+    // Show error in tombstone.
+    android_set_abort_message(buffer);
+
+    // Show error in logcat.
+    openlog("libc++abi", 0, 0);
+    syslog(LOG_CRIT, "%s", buffer);
+    closelog();
+#else
+    // The good error reporting wasn't available in Android until L. Since we're
+    // about to abort anyway, just call __assert2, which will log _somewhere_
+    // (tombstone and/or logcat) in older releases.
+    __assert2(__FILE__, __LINE__, __func__, buffer);
+#endif // __ANDROID_API__ >= 21
+#endif // __BIONIC__
+
+    abort();
+}
diff --git a/lib/libcxxabi/src/abort_message.h b/lib/libcxxabi/src/abort_message.h
new file mode 100644
index 0000000000..7cb11f4c2f
--- /dev/null
+++ b/lib/libcxxabi/src/abort_message.h
@@ -0,0 +1,26 @@
+//===-------------------------- abort_message.h-----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __ABORT_MESSAGE_H_
+#define __ABORT_MESSAGE_H_
+
+#include "cxxabi.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+_LIBCXXABI_HIDDEN _LIBCXXABI_NORETURN void
+abort_message(const char *format, ...) __attribute__((format(printf, 1, 2)));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
diff --git a/lib/libcxxabi/src/cxa_aux_runtime.cpp b/lib/libcxxabi/src/cxa_aux_runtime.cpp
new file mode 100644
index 0000000000..0ed1a72279
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_aux_runtime.cpp
@@ -0,0 +1,43 @@
+//===------------------------ cxa_aux_runtime.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+// This file implements the "Auxiliary Runtime APIs"
+// https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#cxx-aux
+//===----------------------------------------------------------------------===//
+
+#include "cxxabi.h"
+#include <new>
+#include <typeinfo>
+
+namespace __cxxabiv1 {
+extern "C" {
+_LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_bad_cast(void) {
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+  throw std::bad_cast();
+#else
+  std::terminate();
+#endif
+}
+
+_LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void __cxa_bad_typeid(void) {
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+  throw std::bad_typeid();
+#else
+  std::terminate();
+#endif
+}
+
+_LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void
+__cxa_throw_bad_array_new_length(void) {
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+  throw std::bad_array_new_length();
+#else
+  std::terminate();
+#endif
+}
+} // extern "C"
+} // abi
diff --git a/lib/libcxxabi/src/cxa_default_handlers.cpp b/lib/libcxxabi/src/cxa_default_handlers.cpp
new file mode 100644
index 0000000000..d2f823d2b7
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_default_handlers.cpp
@@ -0,0 +1,124 @@
+//===------------------------- cxa_default_handlers.cpp -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+// This file implements the default terminate_handler and unexpected_handler.
+//===----------------------------------------------------------------------===//
+
+#include <exception>
+#include <stdlib.h>
+#include "abort_message.h"
+#include "cxxabi.h"
+#include "cxa_handlers.h"
+#include "cxa_exception.h"
+#include "private_typeinfo.h"
+#include "include/atomic_support.h"
+
+#if !defined(LIBCXXABI_SILENT_TERMINATE)
+
+_LIBCPP_SAFE_STATIC
+static const char* cause = "uncaught";
+
+__attribute__((noreturn))
+static void demangling_terminate_handler()
+{
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+    // If there might be an uncaught exception
+    using namespace __cxxabiv1;
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (globals)
+    {
+        __cxa_exception* exception_header = globals->caughtExceptions;
+        // If there is an uncaught exception
+        if (exception_header)
+        {
+            _Unwind_Exception* unwind_exception =
+                reinterpret_cast<_Unwind_Exception*>(exception_header + 1) - 1;
+            if (__isOurExceptionClass(unwind_exception))
+            {
+                void* thrown_object =
+                    __getExceptionClass(unwind_exception) == kOurDependentExceptionClass ?
+                        ((__cxa_dependent_exception*)exception_header)->primaryException :
+                        exception_header + 1;
+                const __shim_type_info* thrown_type =
+                    static_cast<const __shim_type_info*>(exception_header->exceptionType);
+                // Try to get demangled name of thrown_type
+                int status;
+                char buf[1024];
+                size_t len = sizeof(buf);
+                const char* name = __cxa_demangle(thrown_type->name(), buf, &len, &status);
+                if (status != 0)
+                    name = thrown_type->name();
+                // If the uncaught exception can be caught with std::exception&
+                const __shim_type_info* catch_type =
+                    static_cast<const __shim_type_info*>(&typeid(std::exception));
+                if (catch_type->can_catch(thrown_type, thrown_object))
+                {
+                    // Include the what() message from the exception
+                    const std::exception* e = static_cast<const std::exception*>(thrown_object);
+                    abort_message("terminating with %s exception of type %s: %s",
+                                  cause, name, e->what());
+                }
+                else
+                    // Else just note that we're terminating with an exception
+                    abort_message("terminating with %s exception of type %s",
+                                   cause, name);
+            }
+            else
+                // Else we're terminating with a foreign exception
+                abort_message("terminating with %s foreign exception", cause);
+        }
+    }
+#endif
+    // Else just note that we're terminating
+    abort_message("terminating");
+}
+
+__attribute__((noreturn))
+static void demangling_unexpected_handler()
+{
+    cause = "unexpected";
+    std::terminate();
+}
+
+static constexpr std::terminate_handler default_terminate_handler = demangling_terminate_handler;
+static constexpr std::terminate_handler default_unexpected_handler = demangling_unexpected_handler;
+#else
+static constexpr std::terminate_handler default_terminate_handler = ::abort;
+static constexpr std::terminate_handler default_unexpected_handler = std::terminate;
+#endif
+
+//
+// Global variables that hold the pointers to the current handler
+//
+_LIBCXXABI_DATA_VIS
+_LIBCPP_SAFE_STATIC std::terminate_handler __cxa_terminate_handler = default_terminate_handler;
+
+_LIBCXXABI_DATA_VIS
+_LIBCPP_SAFE_STATIC std::unexpected_handler __cxa_unexpected_handler = default_unexpected_handler;
+
+namespace std
+{
+
+unexpected_handler
+set_unexpected(unexpected_handler func) _NOEXCEPT
+{
+    if (func == 0)
+        func = default_unexpected_handler;
+    return __libcpp_atomic_exchange(&__cxa_unexpected_handler, func,
+                                    _AO_Acq_Rel);
+}
+
+terminate_handler
+set_terminate(terminate_handler func) _NOEXCEPT
+{
+    if (func == 0)
+        func = default_terminate_handler;
+    return __libcpp_atomic_exchange(&__cxa_terminate_handler, func,
+                                    _AO_Acq_Rel);
+}
+
+}
diff --git a/lib/libcxxabi/src/cxa_demangle.cpp b/lib/libcxxabi/src/cxa_demangle.cpp
new file mode 100644
index 0000000000..3045f6edb3
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_demangle.cpp
@@ -0,0 +1,366 @@
+//===-------------------------- cxa_demangle.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// FIXME: (possibly) incomplete list of features that clang mangles that this
+// file does not yet support:
+//   - C++ modules TS
+
+#include "demangle/ItaniumDemangle.h"
+#include "__cxxabi_config.h"
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <numeric>
+#include <utility>
+
+using namespace itanium_demangle;
+
+constexpr const char *itanium_demangle::FloatData<float>::spec;
+constexpr const char *itanium_demangle::FloatData<double>::spec;
+constexpr const char *itanium_demangle::FloatData<long double>::spec;
+
+// <discriminator> := _ <non-negative number>      # when number < 10
+//                 := __ <non-negative number> _   # when number >= 10
+//  extension      := decimal-digit+               # at the end of string
+const char *itanium_demangle::parse_discriminator(const char *first,
+                                                  const char *last) {
+  // parse but ignore discriminator
+  if (first != last) {
+    if (*first == '_') {
+      const char *t1 = first + 1;
+      if (t1 != last) {
+        if (std::isdigit(*t1))
+          first = t1 + 1;
+        else if (*t1 == '_') {
+          for (++t1; t1 != last && std::isdigit(*t1); ++t1)
+            ;
+          if (t1 != last && *t1 == '_')
+            first = t1 + 1;
+        }
+      }
+    } else if (std::isdigit(*first)) {
+      const char *t1 = first + 1;
+      for (; t1 != last && std::isdigit(*t1); ++t1)
+        ;
+      if (t1 == last)
+        first = last;
+    }
+  }
+  return first;
+}
+
+#ifndef NDEBUG
+namespace {
+struct DumpVisitor {
+  unsigned Depth = 0;
+  bool PendingNewline = false;
+
+  template<typename NodeT> static constexpr bool wantsNewline(const NodeT *) {
+    return true;
+  }
+  static bool wantsNewline(NodeArray A) { return !A.empty(); }
+  static constexpr bool wantsNewline(...) { return false; }
+
+  template<typename ...Ts> static bool anyWantNewline(Ts ...Vs) {
+    for (bool B : {wantsNewline(Vs)...})
+      if (B)
+        return true;
+    return false;
+  }
+
+  void printStr(const char *S) { fprintf(stderr, "%s", S); }
+  void print(StringView SV) {
+    fprintf(stderr, "\"%.*s\"", (int)SV.size(), SV.begin());
+  }
+  void print(const Node *N) {
+    if (N)
+      N->visit(std::ref(*this));
+    else
+      printStr("<null>");
+  }
+  void print(NodeArray A) {
+    ++Depth;
+    printStr("{");
+    bool First = true;
+    for (const Node *N : A) {
+      if (First)
+        print(N);
+      else
+        printWithComma(N);
+      First = false;
+    }
+    printStr("}");
+    --Depth;
+  }
+
+  // Overload used when T is exactly 'bool', not merely convertible to 'bool'.
+  void print(bool B) { printStr(B ? "true" : "false"); }
+
+  template <class T>
+  typename std::enable_if<std::is_unsigned<T>::value>::type print(T N) {
+    fprintf(stderr, "%llu", (unsigned long long)N);
+  }
+
+  template <class T>
+  typename std::enable_if<std::is_signed<T>::value>::type print(T N) {
+    fprintf(stderr, "%lld", (long long)N);
+  }
+
+  void print(ReferenceKind RK) {
+    switch (RK) {
+    case ReferenceKind::LValue:
+      return printStr("ReferenceKind::LValue");
+    case ReferenceKind::RValue:
+      return printStr("ReferenceKind::RValue");
+    }
+  }
+  void print(FunctionRefQual RQ) {
+    switch (RQ) {
+    case FunctionRefQual::FrefQualNone:
+      return printStr("FunctionRefQual::FrefQualNone");
+    case FunctionRefQual::FrefQualLValue:
+      return printStr("FunctionRefQual::FrefQualLValue");
+    case FunctionRefQual::FrefQualRValue:
+      return printStr("FunctionRefQual::FrefQualRValue");
+    }
+  }
+  void print(Qualifiers Qs) {
+    if (!Qs) return printStr("QualNone");
+    struct QualName { Qualifiers Q; const char *Name; } Names[] = {
+      {QualConst, "QualConst"},
+      {QualVolatile, "QualVolatile"},
+      {QualRestrict, "QualRestrict"},
+    };
+    for (QualName Name : Names) {
+      if (Qs & Name.Q) {
+        printStr(Name.Name);
+        Qs = Qualifiers(Qs & ~Name.Q);
+        if (Qs) printStr(" | ");
+      }
+    }
+  }
+  void print(SpecialSubKind SSK) {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      return printStr("SpecialSubKind::allocator");
+    case SpecialSubKind::basic_string:
+      return printStr("SpecialSubKind::basic_string");
+    case SpecialSubKind::string:
+      return printStr("SpecialSubKind::string");
+    case SpecialSubKind::istream:
+      return printStr("SpecialSubKind::istream");
+    case SpecialSubKind::ostream:
+      return printStr("SpecialSubKind::ostream");
+    case SpecialSubKind::iostream:
+      return printStr("SpecialSubKind::iostream");
+    }
+  }
+  void print(TemplateParamKind TPK) {
+    switch (TPK) {
+    case TemplateParamKind::Type:
+      return printStr("TemplateParamKind::Type");
+    case TemplateParamKind::NonType:
+      return printStr("TemplateParamKind::NonType");
+    case TemplateParamKind::Template:
+      return printStr("TemplateParamKind::Template");
+    }
+  }
+
+  void newLine() {
+    printStr("\n");
+    for (unsigned I = 0; I != Depth; ++I)
+      printStr(" ");
+    PendingNewline = false;
+  }
+
+  template<typename T> void printWithPendingNewline(T V) {
+    print(V);
+    if (wantsNewline(V))
+      PendingNewline = true;
+  }
+
+  template<typename T> void printWithComma(T V) {
+    if (PendingNewline || wantsNewline(V)) {
+      printStr(",");
+      newLine();
+    } else {
+      printStr(", ");
+    }
+
+    printWithPendingNewline(V);
+  }
+
+  struct CtorArgPrinter {
+    DumpVisitor &Visitor;
+
+    template<typename T, typename ...Rest> void operator()(T V, Rest ...Vs) {
+      if (Visitor.anyWantNewline(V, Vs...))
+        Visitor.newLine();
+      Visitor.printWithPendingNewline(V);
+      int PrintInOrder[] = { (Visitor.printWithComma(Vs), 0)..., 0 };
+      (void)PrintInOrder;
+    }
+  };
+
+  template<typename NodeT> void operator()(const NodeT *Node) {
+    Depth += 2;
+    fprintf(stderr, "%s(", itanium_demangle::NodeKind<NodeT>::name());
+    Node->match(CtorArgPrinter{*this});
+    fprintf(stderr, ")");
+    Depth -= 2;
+  }
+
+  void operator()(const ForwardTemplateReference *Node) {
+    Depth += 2;
+    fprintf(stderr, "ForwardTemplateReference(");
+    if (Node->Ref && !Node->Printing) {
+      Node->Printing = true;
+      CtorArgPrinter{*this}(Node->Ref);
+      Node->Printing = false;
+    } else {
+      CtorArgPrinter{*this}(Node->Index);
+    }
+    fprintf(stderr, ")");
+    Depth -= 2;
+  }
+};
+}
+
+void itanium_demangle::Node::dump() const {
+  DumpVisitor V;
+  visit(std::ref(V));
+  V.newLine();
+}
+#endif
+
+namespace {
+class BumpPointerAllocator {
+  struct BlockMeta {
+    BlockMeta* Next;
+    size_t Current;
+  };
+
+  static constexpr size_t AllocSize = 4096;
+  static constexpr size_t UsableAllocSize = AllocSize - sizeof(BlockMeta);
+
+  alignas(long double) char InitialBuffer[AllocSize];
+  BlockMeta* BlockList = nullptr;
+
+  void grow() {
+    char* NewMeta = static_cast<char *>(std::malloc(AllocSize));
+    if (NewMeta == nullptr)
+      std::terminate();
+    BlockList = new (NewMeta) BlockMeta{BlockList, 0};
+  }
+
+  void* allocateMassive(size_t NBytes) {
+    NBytes += sizeof(BlockMeta);
+    BlockMeta* NewMeta = reinterpret_cast<BlockMeta*>(std::malloc(NBytes));
+    if (NewMeta == nullptr)
+      std::terminate();
+    BlockList->Next = new (NewMeta) BlockMeta{BlockList->Next, 0};
+    return static_cast<void*>(NewMeta + 1);
+  }
+
+public:
+  BumpPointerAllocator()
+      : BlockList(new (InitialBuffer) BlockMeta{nullptr, 0}) {}
+
+  void* allocate(size_t N) {
+    N = (N + 15u) & ~15u;
+    if (N + BlockList->Current >= UsableAllocSize) {
+      if (N > UsableAllocSize)
+        return allocateMassive(N);
+      grow();
+    }
+    BlockList->Current += N;
+    return static_cast<void*>(reinterpret_cast<char*>(BlockList + 1) +
+                              BlockList->Current - N);
+  }
+
+  void reset() {
+    while (BlockList) {
+      BlockMeta* Tmp = BlockList;
+      BlockList = BlockList->Next;
+      if (reinterpret_cast<char*>(Tmp) != InitialBuffer)
+        std::free(Tmp);
+    }
+    BlockList = new (InitialBuffer) BlockMeta{nullptr, 0};
+  }
+
+  ~BumpPointerAllocator() { reset(); }
+};
+
+class DefaultAllocator {
+  BumpPointerAllocator Alloc;
+
+public:
+  void reset() { Alloc.reset(); }
+
+  template<typename T, typename ...Args> T *makeNode(Args &&...args) {
+    return new (Alloc.allocate(sizeof(T)))
+        T(std::forward<Args>(args)...);
+  }
+
+  void *allocateNodeArray(size_t sz) {
+    return Alloc.allocate(sizeof(Node *) * sz);
+  }
+};
+}  // unnamed namespace
+
+//===----------------------------------------------------------------------===//
+// Code beyond this point should not be synchronized with LLVM.
+//===----------------------------------------------------------------------===//
+
+using Demangler = itanium_demangle::ManglingParser<DefaultAllocator>;
+
+namespace {
+enum : int {
+  demangle_invalid_args = -3,
+  demangle_invalid_mangled_name = -2,
+  demangle_memory_alloc_failure = -1,
+  demangle_success = 0,
+};
+}
+
+namespace __cxxabiv1 {
+extern "C" _LIBCXXABI_FUNC_VIS char *
+__cxa_demangle(const char *MangledName, char *Buf, size_t *N, int *Status) {
+  if (MangledName == nullptr || (Buf != nullptr && N == nullptr)) {
+    if (Status)
+      *Status = demangle_invalid_args;
+    return nullptr;
+  }
+
+  int InternalStatus = demangle_success;
+  Demangler Parser(MangledName, MangledName + std::strlen(MangledName));
+  OutputStream S;
+
+  Node *AST = Parser.parse();
+
+  if (AST == nullptr)
+    InternalStatus = demangle_invalid_mangled_name;
+  else if (!initializeOutputStream(Buf, N, S, 1024))
+    InternalStatus = demangle_memory_alloc_failure;
+  else {
+    assert(Parser.ForwardTemplateRefs.empty());
+    AST->print(S);
+    S += '\0';
+    if (N != nullptr)
+      *N = S.getCurrentPosition();
+    Buf = S.getBuffer();
+  }
+
+  if (Status)
+    *Status = InternalStatus;
+  return InternalStatus == demangle_success ? Buf : nullptr;
+}
+}  // __cxxabiv1
diff --git a/lib/libcxxabi/src/cxa_exception.cpp b/lib/libcxxabi/src/cxa_exception.cpp
new file mode 100644
index 0000000000..ebb05ce542
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_exception.cpp
@@ -0,0 +1,755 @@
+//===------------------------- cxa_exception.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Exception Handling APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+//===----------------------------------------------------------------------===//
+
+#include "cxxabi.h"
+
+#include <exception>        // for std::terminate
+#include <string.h>         // for memset
+#include "cxa_exception.h"
+#include "cxa_handlers.h"
+#include "fallback_malloc.h"
+#include "include/atomic_support.h"
+
+#if __has_feature(address_sanitizer)
+extern "C" void __asan_handle_no_return(void);
+#endif
+
+// +---------------------------+-----------------------------+---------------+
+// | __cxa_exception           | _Unwind_Exception CLNGC++\0 | thrown object |
+// +---------------------------+-----------------------------+---------------+
+//                                                           ^
+//                                                           |
+//   +-------------------------------------------------------+
+//   |
+// +---------------------------+-----------------------------+
+// | __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 |
+// +---------------------------+-----------------------------+
+
+namespace __cxxabiv1 {
+
+//  Utility routines
+static
+inline
+__cxa_exception*
+cxa_exception_from_thrown_object(void* thrown_object)
+{
+    return static_cast<__cxa_exception*>(thrown_object) - 1;
+}
+
+// Note:  This is never called when exception_header is masquerading as a
+//        __cxa_dependent_exception.
+static
+inline
+void*
+thrown_object_from_cxa_exception(__cxa_exception* exception_header)
+{
+    return static_cast<void*>(exception_header + 1);
+}
+
+//  Get the exception object from the unwind pointer.
+//  Relies on the structure layout, where the unwind pointer is right in
+//  front of the user's exception object
+static
+inline
+__cxa_exception*
+cxa_exception_from_exception_unwind_exception(_Unwind_Exception* unwind_exception)
+{
+    return cxa_exception_from_thrown_object(unwind_exception + 1 );
+}
+
+// Round s up to next multiple of a.
+static inline
+size_t aligned_allocation_size(size_t s, size_t a) {
+    return (s + a - 1) & ~(a - 1);
+}
+
+static inline
+size_t cxa_exception_size_from_exception_thrown_size(size_t size) {
+    return aligned_allocation_size(size + sizeof (__cxa_exception),
+                                   alignof(__cxa_exception));
+}
+
+void __setExceptionClass(_Unwind_Exception* unwind_exception, uint64_t newValue) {
+    ::memcpy(&unwind_exception->exception_class, &newValue, sizeof(newValue));
+}
+
+
+static void setOurExceptionClass(_Unwind_Exception* unwind_exception) {
+    __setExceptionClass(unwind_exception, kOurExceptionClass);
+}
+
+static void setDependentExceptionClass(_Unwind_Exception* unwind_exception) {
+    __setExceptionClass(unwind_exception, kOurDependentExceptionClass);
+}
+
+//  Is it one of ours?
+uint64_t __getExceptionClass(const _Unwind_Exception* unwind_exception) {
+    // On x86 and some ARM unwinders, unwind_exception->exception_class is
+    // a uint64_t. On other ARM unwinders, it is a char[8].
+    // See: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
+    // So we just copy it into a uint64_t to be sure.
+    uint64_t exClass;
+    ::memcpy(&exClass, &unwind_exception->exception_class, sizeof(exClass));
+    return exClass;
+}
+
+bool __isOurExceptionClass(const _Unwind_Exception* unwind_exception) {
+    return (__getExceptionClass(unwind_exception) & get_vendor_and_language) ==
+           (kOurExceptionClass                    & get_vendor_and_language);
+}
+
+static bool isDependentException(_Unwind_Exception* unwind_exception) {
+    return (__getExceptionClass(unwind_exception) & 0xFF) == 0x01;
+}
+
+//  This does not need to be atomic
+static inline int incrementHandlerCount(__cxa_exception *exception) {
+    return ++exception->handlerCount;
+}
+
+//  This does not need to be atomic
+static inline  int decrementHandlerCount(__cxa_exception *exception) {
+    return --exception->handlerCount;
+}
+
+/*
+    If reason isn't _URC_FOREIGN_EXCEPTION_CAUGHT, then the terminateHandler
+    stored in exc is called.  Otherwise the exceptionDestructor stored in
+    exc is called, and then the memory for the exception is deallocated.
+
+    This is never called for a __cxa_dependent_exception.
+*/
+static
+void
+exception_cleanup_func(_Unwind_Reason_Code reason, _Unwind_Exception* unwind_exception)
+{
+    __cxa_exception* exception_header = cxa_exception_from_exception_unwind_exception(unwind_exception);
+    if (_URC_FOREIGN_EXCEPTION_CAUGHT != reason)
+        std::__terminate(exception_header->terminateHandler);
+    // Just in case there exists a dependent exception that is pointing to this,
+    //    check the reference count and only destroy this if that count goes to zero.
+    __cxa_decrement_exception_refcount(unwind_exception + 1);
+}
+
+static _LIBCXXABI_NORETURN void failed_throw(__cxa_exception* exception_header) {
+//  Section 2.5.3 says:
+//      * For purposes of this ABI, several things are considered exception handlers:
+//      ** A terminate() call due to a throw.
+//  and
+//      * Upon entry, Following initialization of the catch parameter,
+//          a handler must call:
+//      * void *__cxa_begin_catch(void *exceptionObject );
+    (void) __cxa_begin_catch(&exception_header->unwindHeader);
+    std::__terminate(exception_header->terminateHandler);
+}
+
+// Return the offset of the __cxa_exception header from the start of the
+// allocated buffer. If __cxa_exception's alignment is smaller than the maximum
+// useful alignment for the target machine, padding has to be inserted before
+// the header to ensure the thrown object that follows the header is
+// sufficiently aligned. This happens if _Unwind_exception isn't double-word
+// aligned (on Darwin, for example).
+static size_t get_cxa_exception_offset() {
+  struct S {
+  } __attribute__((aligned));
+
+  // Compute the maximum alignment for the target machine.
+  constexpr size_t alignment = alignof(S);
+  constexpr size_t excp_size = sizeof(__cxa_exception);
+  constexpr size_t aligned_size =
+      (excp_size + alignment - 1) / alignment * alignment;
+  constexpr size_t offset = aligned_size - excp_size;
+  static_assert((offset == 0 || alignof(_Unwind_Exception) < alignment),
+                "offset is non-zero only if _Unwind_Exception isn't aligned");
+  return offset;
+}
+
+extern "C" {
+
+//  Allocate a __cxa_exception object, and zero-fill it.
+//  Reserve "thrown_size" bytes on the end for the user's exception
+//  object. Zero-fill the object. If memory can't be allocated, call
+//  std::terminate. Return a pointer to the memory to be used for the
+//  user's exception object.
+void *__cxa_allocate_exception(size_t thrown_size) throw() {
+    size_t actual_size = cxa_exception_size_from_exception_thrown_size(thrown_size);
+
+    // Allocate extra space before the __cxa_exception header to ensure the
+    // start of the thrown object is sufficiently aligned.
+    size_t header_offset = get_cxa_exception_offset();
+    char *raw_buffer =
+        (char *)__aligned_malloc_with_fallback(header_offset + actual_size);
+    if (NULL == raw_buffer)
+        std::terminate();
+    __cxa_exception *exception_header =
+        static_cast<__cxa_exception *>((void *)(raw_buffer + header_offset));
+    ::memset(exception_header, 0, actual_size);
+    return thrown_object_from_cxa_exception(exception_header);
+}
+
+
+//  Free a __cxa_exception object allocated with __cxa_allocate_exception.
+void __cxa_free_exception(void *thrown_object) throw() {
+    // Compute the size of the padding before the header.
+    size_t header_offset = get_cxa_exception_offset();
+    char *raw_buffer =
+        ((char *)cxa_exception_from_thrown_object(thrown_object)) - header_offset;
+    __aligned_free_with_fallback((void *)raw_buffer);
+}
+
+
+//  This function shall allocate a __cxa_dependent_exception and
+//  return a pointer to it. (Really to the object, not past its' end).
+//  Otherwise, it will work like __cxa_allocate_exception.
+void * __cxa_allocate_dependent_exception () {
+    size_t actual_size = sizeof(__cxa_dependent_exception);
+    void *ptr = __aligned_malloc_with_fallback(actual_size);
+    if (NULL == ptr)
+        std::terminate();
+    ::memset(ptr, 0, actual_size);
+    return ptr;
+}
+
+
+//  This function shall free a dependent_exception.
+//  It does not affect the reference count of the primary exception.
+void __cxa_free_dependent_exception (void * dependent_exception) {
+    __aligned_free_with_fallback(dependent_exception);
+}
+
+
+// 2.4.3 Throwing the Exception Object
+/*
+After constructing the exception object with the throw argument value,
+the generated code calls the __cxa_throw runtime library routine. This
+routine never returns.
+
+The __cxa_throw routine will do the following:
+
+* Obtain the __cxa_exception header from the thrown exception object address,
+which can be computed as follows:
+ __cxa_exception *header = ((__cxa_exception *) thrown_exception - 1);
+* Save the current unexpected_handler and terminate_handler in the __cxa_exception header.
+* Save the tinfo and dest arguments in the __cxa_exception header.
+* Set the exception_class field in the unwind header. This is a 64-bit value
+representing the ASCII string "XXXXC++\0", where "XXXX" is a
+vendor-dependent string. That is, for implementations conforming to this
+ABI, the low-order 4 bytes of this 64-bit value will be "C++\0".
+* Increment the uncaught_exception flag.
+* Call _Unwind_RaiseException in the system unwind library, Its argument is the
+pointer to the thrown exception, which __cxa_throw itself received as an argument.
+__Unwind_RaiseException begins the process of stack unwinding, described
+in Section 2.5. In special cases, such as an inability to find a
+handler, _Unwind_RaiseException may return. In that case, __cxa_throw
+will call terminate, assuming that there was no handler for the
+exception.
+*/
+void
+__cxa_throw(void *thrown_object, std::type_info *tinfo, void (*dest)(void *)) {
+    __cxa_eh_globals *globals = __cxa_get_globals();
+    __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+
+    exception_header->unexpectedHandler = std::get_unexpected();
+    exception_header->terminateHandler  = std::get_terminate();
+    exception_header->exceptionType = tinfo;
+    exception_header->exceptionDestructor = dest;
+    setOurExceptionClass(&exception_header->unwindHeader);
+    exception_header->referenceCount = 1;  // This is a newly allocated exception, no need for thread safety.
+    globals->uncaughtExceptions += 1;   // Not atomically, since globals are thread-local
+
+    exception_header->unwindHeader.exception_cleanup = exception_cleanup_func;
+
+#if __has_feature(address_sanitizer)
+    // Inform the ASan runtime that now might be a good time to clean stuff up.
+    __asan_handle_no_return();
+#endif
+
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
+#else
+    _Unwind_RaiseException(&exception_header->unwindHeader);
+#endif
+    //  This only happens when there is no handler, or some unexpected unwinding
+    //     error happens.
+    failed_throw(exception_header);
+}
+
+
+// 2.5.3 Exception Handlers
+/*
+The adjusted pointer is computed by the personality routine during phase 1
+  and saved in the exception header (either __cxa_exception or
+  __cxa_dependent_exception).
+
+  Requires:  exception is native
+*/
+void *__cxa_get_exception_ptr(void *unwind_exception) throw() {
+#if defined(_LIBCXXABI_ARM_EHABI)
+    return reinterpret_cast<void*>(
+        static_cast<_Unwind_Control_Block*>(unwind_exception)->barrier_cache.bitpattern[0]);
+#else
+    return cxa_exception_from_exception_unwind_exception(
+        static_cast<_Unwind_Exception*>(unwind_exception))->adjustedPtr;
+#endif
+}
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+/*
+The routine to be called before the cleanup.  This will save __cxa_exception in
+__cxa_eh_globals, so that __cxa_end_cleanup() can recover later.
+*/
+bool __cxa_begin_cleanup(void *unwind_arg) throw() {
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(unwind_arg);
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header =
+        cxa_exception_from_exception_unwind_exception(unwind_exception);
+
+    if (__isOurExceptionClass(unwind_exception))
+    {
+        if (0 == exception_header->propagationCount)
+        {
+            exception_header->nextPropagatingException = globals->propagatingExceptions;
+            globals->propagatingExceptions = exception_header;
+        }
+        ++exception_header->propagationCount;
+    }
+    else
+    {
+        // If the propagatingExceptions stack is not empty, since we can't
+        // chain the foreign exception, terminate it.
+        if (NULL != globals->propagatingExceptions)
+            std::terminate();
+        globals->propagatingExceptions = exception_header;
+    }
+    return true;
+}
+
+/*
+The routine to be called after the cleanup has been performed.  It will get the
+propagating __cxa_exception from __cxa_eh_globals, and continue the stack
+unwinding with _Unwind_Resume.
+
+According to ARM EHABI 8.4.1, __cxa_end_cleanup() should not clobber any
+register, thus we have to write this function in assembly so that we can save
+{r1, r2, r3}.  We don't have to save r0 because it is the return value and the
+first argument to _Unwind_Resume().  In addition, we are saving r4 in order to
+align the stack to 16 bytes, even though it is a callee-save register.
+*/
+__attribute__((used)) static _Unwind_Exception *
+__cxa_end_cleanup_impl()
+{
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header = globals->propagatingExceptions;
+    if (NULL == exception_header)
+    {
+        // It seems that __cxa_begin_cleanup() is not called properly.
+        // We have no choice but terminate the program now.
+        std::terminate();
+    }
+
+    if (__isOurExceptionClass(&exception_header->unwindHeader))
+    {
+        --exception_header->propagationCount;
+        if (0 == exception_header->propagationCount)
+        {
+            globals->propagatingExceptions = exception_header->nextPropagatingException;
+            exception_header->nextPropagatingException = NULL;
+        }
+    }
+    else
+    {
+        globals->propagatingExceptions = NULL;
+    }
+    return &exception_header->unwindHeader;
+}
+
+asm (
+    "	.pushsection	.text.__cxa_end_cleanup,\"ax\",%progbits\n"
+    "	.globl	__cxa_end_cleanup\n"
+    "	.type	__cxa_end_cleanup,%function\n"
+    "__cxa_end_cleanup:\n"
+    "	push	{r1, r2, r3, r4}\n"
+    "	bl	__cxa_end_cleanup_impl\n"
+    "	pop	{r1, r2, r3, r4}\n"
+    "	bl	_Unwind_Resume\n"
+    "	bl	abort\n"
+    "	.popsection"
+);
+#endif  // defined(_LIBCXXABI_ARM_EHABI)
+
+/*
+This routine can catch foreign or native exceptions.  If native, the exception
+can be a primary or dependent variety.  This routine may remain blissfully
+ignorant of whether the native exception is primary or dependent.
+
+If the exception is native:
+* Increment's the exception's handler count.
+* Push the exception on the stack of currently-caught exceptions if it is not
+  already there (from a rethrow).
+* Decrements the uncaught_exception count.
+* Returns the adjusted pointer to the exception object, which is stored in
+  the __cxa_exception by the personality routine.
+
+If the exception is foreign, this means it did not originate from one of throw
+routines.  The foreign exception does not necessarily have a __cxa_exception
+header.  However we can catch it here with a catch (...), or with a call
+to terminate or unexpected during unwinding.
+* Do not try to increment the exception's handler count, we don't know where
+  it is.
+* Push the exception on the stack of currently-caught exceptions only if the
+  stack is empty.  The foreign exception has no way to link to the current
+  top of stack.  If the stack is not empty, call terminate.  Even with an
+  empty stack, this is hacked in by pushing a pointer to an imaginary
+  __cxa_exception block in front of the foreign exception.  It would be better
+  if the __cxa_eh_globals structure had a stack of _Unwind_Exception, but it
+  doesn't.  It has a stack of __cxa_exception (which has a next* in it).
+* Do not decrement the uncaught_exception count because we didn't increment it
+  in __cxa_throw (or one of our rethrow functions).
+* If we haven't terminated, assume the exception object is just past the
+  _Unwind_Exception and return a pointer to that.
+*/
+void*
+__cxa_begin_catch(void* unwind_arg) throw()
+{
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(unwind_arg);
+    bool native_exception = __isOurExceptionClass(unwind_exception);
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    // exception_header is a hackish offset from a foreign exception, but it
+    //   works as long as we're careful not to try to access any __cxa_exception
+    //   parts.
+    __cxa_exception* exception_header =
+            cxa_exception_from_exception_unwind_exception
+            (
+                static_cast<_Unwind_Exception*>(unwind_exception)
+            );
+    if (native_exception)
+    {
+        // Increment the handler count, removing the flag about being rethrown
+        exception_header->handlerCount = exception_header->handlerCount < 0 ?
+            -exception_header->handlerCount + 1 : exception_header->handlerCount + 1;
+        //  place the exception on the top of the stack if it's not already
+        //    there by a previous rethrow
+        if (exception_header != globals->caughtExceptions)
+        {
+            exception_header->nextException = globals->caughtExceptions;
+            globals->caughtExceptions = exception_header;
+        }
+        globals->uncaughtExceptions -= 1;   // Not atomically, since globals are thread-local
+#if defined(_LIBCXXABI_ARM_EHABI)
+        return reinterpret_cast<void*>(exception_header->unwindHeader.barrier_cache.bitpattern[0]);
+#else
+        return exception_header->adjustedPtr;
+#endif
+    }
+    // Else this is a foreign exception
+    // If the caughtExceptions stack is not empty, terminate
+    if (globals->caughtExceptions != 0)
+        std::terminate();
+    // Push the foreign exception on to the stack
+    globals->caughtExceptions = exception_header;
+    return unwind_exception + 1;
+}
+
+
+/*
+Upon exit for any reason, a handler must call:
+    void __cxa_end_catch ();
+
+This routine can be called for either a native or foreign exception.
+For a native exception:
+* Locates the most recently caught exception and decrements its handler count.
+* Removes the exception from the caught exception stack, if the handler count goes to zero.
+* If the handler count goes down to zero, and the exception was not re-thrown
+  by throw, it locates the primary exception (which may be the same as the one
+  it's handling) and decrements its reference count. If that reference count
+  goes to zero, the function destroys the exception. In any case, if the current
+  exception is a dependent exception, it destroys that.
+
+For a foreign exception:
+* If it has been rethrown, there is nothing to do.
+* Otherwise delete the exception and pop the catch stack to empty.
+*/
+void __cxa_end_catch() {
+  static_assert(sizeof(__cxa_exception) == sizeof(__cxa_dependent_exception),
+                "sizeof(__cxa_exception) must be equal to "
+                "sizeof(__cxa_dependent_exception)");
+  static_assert(__builtin_offsetof(__cxa_exception, referenceCount) ==
+                    __builtin_offsetof(__cxa_dependent_exception,
+                                       primaryException),
+                "the layout of __cxa_exception must match the layout of "
+                "__cxa_dependent_exception");
+  static_assert(__builtin_offsetof(__cxa_exception, handlerCount) ==
+                    __builtin_offsetof(__cxa_dependent_exception, handlerCount),
+                "the layout of __cxa_exception must match the layout of "
+                "__cxa_dependent_exception");
+    __cxa_eh_globals* globals = __cxa_get_globals_fast(); // __cxa_get_globals called in __cxa_begin_catch
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    // If we've rethrown a foreign exception, then globals->caughtExceptions
+    //    will have been made an empty stack by __cxa_rethrow() and there is
+    //    nothing more to be done.  Do nothing!
+    if (NULL != exception_header)
+    {
+        bool native_exception = __isOurExceptionClass(&exception_header->unwindHeader);
+        if (native_exception)
+        {
+            // This is a native exception
+            if (exception_header->handlerCount < 0)
+            {
+                //  The exception has been rethrown by __cxa_rethrow, so don't delete it
+                if (0 == incrementHandlerCount(exception_header))
+                {
+                    //  Remove from the chain of uncaught exceptions
+                    globals->caughtExceptions = exception_header->nextException;
+                    // but don't destroy
+                }
+                // Keep handlerCount negative in case there are nested catch's
+                //   that need to be told that this exception is rethrown.  Don't
+                //   erase this rethrow flag until the exception is recaught.
+            }
+            else
+            {
+                // The native exception has not been rethrown
+                if (0 == decrementHandlerCount(exception_header))
+                {
+                    //  Remove from the chain of uncaught exceptions
+                    globals->caughtExceptions = exception_header->nextException;
+                    // Destroy this exception, being careful to distinguish
+                    //    between dependent and primary exceptions
+                    if (isDependentException(&exception_header->unwindHeader))
+                    {
+                        // Reset exception_header to primaryException and deallocate the dependent exception
+                        __cxa_dependent_exception* dep_exception_header =
+                            reinterpret_cast<__cxa_dependent_exception*>(exception_header);
+                        exception_header =
+                            cxa_exception_from_thrown_object(dep_exception_header->primaryException);
+                        __cxa_free_dependent_exception(dep_exception_header);
+                    }
+                    // Destroy the primary exception only if its referenceCount goes to 0
+                    //    (this decrement must be atomic)
+                    __cxa_decrement_exception_refcount(thrown_object_from_cxa_exception(exception_header));
+                }
+            }
+        }
+        else
+        {
+            // The foreign exception has not been rethrown.  Pop the stack
+            //    and delete it.  If there are nested catch's and they try
+            //    to touch a foreign exception in any way, that is undefined
+            //     behavior.  They likely can't since the only way to catch
+            //     a foreign exception is with catch (...)!
+            _Unwind_DeleteException(&globals->caughtExceptions->unwindHeader);
+            globals->caughtExceptions = 0;
+        }
+    }
+}
+
+// Note:  exception_header may be masquerading as a __cxa_dependent_exception
+//        and that's ok.  exceptionType is there too.
+//        However watch out for foreign exceptions.  Return null for them.
+std::type_info *__cxa_current_exception_type() {
+//  get the current exception
+    __cxa_eh_globals *globals = __cxa_get_globals_fast();
+    if (NULL == globals)
+        return NULL;     //  If there have never been any exceptions, there are none now.
+    __cxa_exception *exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        return NULL;        //  No current exception
+    if (!__isOurExceptionClass(&exception_header->unwindHeader))
+        return NULL;
+    return exception_header->exceptionType;
+}
+
+// 2.5.4 Rethrowing Exceptions
+/*  This routine can rethrow native or foreign exceptions.
+If the exception is native:
+* marks the exception object on top of the caughtExceptions stack
+  (in an implementation-defined way) as being rethrown.
+* If the caughtExceptions stack is empty, it calls terminate()
+  (see [C++FDIS] [except.throw], 15.1.8).
+* It then calls _Unwind_RaiseException which should not return
+   (terminate if it does).
+  Note:  exception_header may be masquerading as a __cxa_dependent_exception
+         and that's ok.
+*/
+void __cxa_rethrow() {
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        std::terminate();      // throw; called outside of a exception handler
+    bool native_exception = __isOurExceptionClass(&exception_header->unwindHeader);
+    if (native_exception)
+    {
+        //  Mark the exception as being rethrown (reverse the effects of __cxa_begin_catch)
+        exception_header->handlerCount = -exception_header->handlerCount;
+        globals->uncaughtExceptions += 1;
+        //  __cxa_end_catch will remove this exception from the caughtExceptions stack if necessary
+    }
+    else  // this is a foreign exception
+    {
+        // The only way to communicate to __cxa_end_catch that we've rethrown
+        //   a foreign exception, so don't delete us, is to pop the stack here
+        //   which must be empty afterwards.  Then __cxa_end_catch will do
+        //   nothing
+        globals->caughtExceptions = 0;
+    }
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
+#else
+    _Unwind_RaiseException(&exception_header->unwindHeader);
+#endif
+
+    //  If we get here, some kind of unwinding error has occurred.
+    //  There is some weird code generation bug happening with
+    //     Apple clang version 4.0 (tags/Apple/clang-418.0.2) (based on LLVM 3.1svn)
+    //     If we call failed_throw here.  Turns up with -O2 or higher, and -Os.
+    __cxa_begin_catch(&exception_header->unwindHeader);
+    if (native_exception)
+        std::__terminate(exception_header->terminateHandler);
+    // Foreign exception: can't get exception_header->terminateHandler
+    std::terminate();
+}
+
+/*
+    If thrown_object is not null, atomically increment the referenceCount field
+    of the __cxa_exception header associated with the thrown object referred to
+    by thrown_object.
+
+    Requires:  If thrown_object is not NULL, it is a native exception.
+*/
+void
+__cxa_increment_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != NULL )
+    {
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(1));
+    }
+}
+
+/*
+    If thrown_object is not null, atomically decrement the referenceCount field
+    of the __cxa_exception header associated with the thrown object referred to
+    by thrown_object.  If the referenceCount drops to zero, destroy and
+    deallocate the exception.
+
+    Requires:  If thrown_object is not NULL, it is a native exception.
+*/
+_LIBCXXABI_NO_CFI
+void __cxa_decrement_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != NULL )
+    {
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        if (std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(-1)) == 0)
+        {
+            if (NULL != exception_header->exceptionDestructor)
+                exception_header->exceptionDestructor(thrown_object);
+            __cxa_free_exception(thrown_object);
+        }
+    }
+}
+
+/*
+    Returns a pointer to the thrown object (if any) at the top of the
+    caughtExceptions stack.  Atomically increment the exception's referenceCount.
+    If there is no such thrown object or if the thrown object is foreign,
+    returns null.
+
+    We can use __cxa_get_globals_fast here to get the globals because if there have
+    been no exceptions thrown, ever, on this thread, we can return NULL without
+    the need to allocate the exception-handling globals.
+*/
+void *__cxa_current_primary_exception() throw() {
+//  get the current exception
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (NULL == globals)
+        return NULL;        //  If there are no globals, there is no exception
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        return NULL;        //  No current exception
+    if (!__isOurExceptionClass(&exception_header->unwindHeader))
+        return NULL;        // Can't capture a foreign exception (no way to refcount it)
+    if (isDependentException(&exception_header->unwindHeader)) {
+        __cxa_dependent_exception* dep_exception_header =
+            reinterpret_cast<__cxa_dependent_exception*>(exception_header);
+        exception_header = cxa_exception_from_thrown_object(dep_exception_header->primaryException);
+    }
+    void* thrown_object = thrown_object_from_cxa_exception(exception_header);
+    __cxa_increment_exception_refcount(thrown_object);
+    return thrown_object;
+}
+
+/*
+    If reason isn't _URC_FOREIGN_EXCEPTION_CAUGHT, then the terminateHandler
+    stored in exc is called.  Otherwise the referenceCount stored in the
+    primary exception is decremented, destroying the primary if necessary.
+    Finally the dependent exception is destroyed.
+*/
+static
+void
+dependent_exception_cleanup(_Unwind_Reason_Code reason, _Unwind_Exception* unwind_exception)
+{
+    __cxa_dependent_exception* dep_exception_header =
+                      reinterpret_cast<__cxa_dependent_exception*>(unwind_exception + 1) - 1;
+    if (_URC_FOREIGN_EXCEPTION_CAUGHT != reason)
+        std::__terminate(dep_exception_header->terminateHandler);
+    __cxa_decrement_exception_refcount(dep_exception_header->primaryException);
+    __cxa_free_dependent_exception(dep_exception_header);
+}
+
+/*
+    If thrown_object is not null, allocate, initialize and throw a dependent
+    exception.
+*/
+void
+__cxa_rethrow_primary_exception(void* thrown_object)
+{
+    if ( thrown_object != NULL )
+    {
+        // thrown_object guaranteed to be native because
+        //   __cxa_current_primary_exception returns NULL for foreign exceptions
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        __cxa_dependent_exception* dep_exception_header =
+            static_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception());
+        dep_exception_header->primaryException = thrown_object;
+        __cxa_increment_exception_refcount(thrown_object);
+        dep_exception_header->exceptionType = exception_header->exceptionType;
+        dep_exception_header->unexpectedHandler = std::get_unexpected();
+        dep_exception_header->terminateHandler = std::get_terminate();
+        setDependentExceptionClass(&dep_exception_header->unwindHeader);
+        __cxa_get_globals()->uncaughtExceptions += 1;
+        dep_exception_header->unwindHeader.exception_cleanup = dependent_exception_cleanup;
+#ifdef __USING_SJLJ_EXCEPTIONS__
+        _Unwind_SjLj_RaiseException(&dep_exception_header->unwindHeader);
+#else
+        _Unwind_RaiseException(&dep_exception_header->unwindHeader);
+#endif
+        // Some sort of unwinding error.  Note that terminate is a handler.
+        __cxa_begin_catch(&dep_exception_header->unwindHeader);
+    }
+    // If we return client will call terminate()
+}
+
+bool
+__cxa_uncaught_exception() throw() { return __cxa_uncaught_exceptions() != 0; }
+
+unsigned int
+__cxa_uncaught_exceptions() throw()
+{
+    // This does not report foreign exceptions in flight
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (globals == 0)
+        return 0;
+    return globals->uncaughtExceptions;
+}
+
+}  // extern "C"
+
+}  // abi
diff --git a/lib/libcxxabi/src/cxa_exception.h b/lib/libcxxabi/src/cxa_exception.h
new file mode 100644
index 0000000000..8c6c8bca85
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_exception.h
@@ -0,0 +1,164 @@
+//===------------------------- cxa_exception.h ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Exception Handling APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _CXA_EXCEPTION_H
+#define _CXA_EXCEPTION_H
+
+#include <exception> // for std::unexpected_handler and std::terminate_handler
+#include "cxxabi.h"
+#include "unwind.h"
+
+namespace __cxxabiv1 {
+
+static const uint64_t kOurExceptionClass          = 0x434C4E47432B2B00; // CLNGC++\0
+static const uint64_t kOurDependentExceptionClass = 0x434C4E47432B2B01; // CLNGC++\1
+static const uint64_t get_vendor_and_language     = 0xFFFFFFFFFFFFFF00; // mask for CLNGC++
+
+_LIBCXXABI_HIDDEN uint64_t __getExceptionClass  (const _Unwind_Exception*);
+_LIBCXXABI_HIDDEN void     __setExceptionClass  (      _Unwind_Exception*, uint64_t);
+_LIBCXXABI_HIDDEN bool     __isOurExceptionClass(const _Unwind_Exception*);
+
+struct _LIBCXXABI_HIDDEN __cxa_exception {
+#if defined(__LP64__) || defined(_WIN64) || defined(_LIBCXXABI_ARM_EHABI)
+    // Now _Unwind_Exception is marked with __attribute__((aligned)),
+    // which implies __cxa_exception is also aligned. Insert padding
+    // in the beginning of the struct, rather than before unwindHeader.
+    void *reserve;
+
+    // This is a new field to support C++ 0x exception_ptr.
+    // For binary compatibility it is at the start of this
+    // struct which is prepended to the object thrown in
+    // __cxa_allocate_exception.
+    size_t referenceCount;
+#endif
+
+    //  Manage the exception object itself.
+    std::type_info *exceptionType;
+    void (*exceptionDestructor)(void *);
+    std::unexpected_handler unexpectedHandler;
+    std::terminate_handler  terminateHandler;
+
+    __cxa_exception *nextException;
+
+    int handlerCount;
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+    __cxa_exception* nextPropagatingException;
+    int propagationCount;
+#else
+    int handlerSwitchValue;
+    const unsigned char *actionRecord;
+    const unsigned char *languageSpecificData;
+    void *catchTemp;
+    void *adjustedPtr;
+#endif
+
+#if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
+    // This is a new field to support C++ 0x exception_ptr.
+    // For binary compatibility it is placed where the compiler
+    // previously adding padded to 64-bit align unwindHeader.
+    size_t referenceCount;
+#endif
+    _Unwind_Exception unwindHeader;
+};
+
+// http://sourcery.mentor.com/archives/cxx-abi-dev/msg01924.html
+// The layout of this structure MUST match the layout of __cxa_exception, with
+// primaryException instead of referenceCount.
+struct _LIBCXXABI_HIDDEN __cxa_dependent_exception {
+#if defined(__LP64__) || defined(_WIN64) || defined(_LIBCXXABI_ARM_EHABI)
+    void* reserve; // padding.
+    void* primaryException;
+#endif
+
+    std::type_info *exceptionType;
+    void (*exceptionDestructor)(void *);
+    std::unexpected_handler unexpectedHandler;
+    std::terminate_handler terminateHandler;
+
+    __cxa_exception *nextException;
+
+    int handlerCount;
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+    __cxa_exception* nextPropagatingException;
+    int propagationCount;
+#else
+    int handlerSwitchValue;
+    const unsigned char *actionRecord;
+    const unsigned char *languageSpecificData;
+    void * catchTemp;
+    void *adjustedPtr;
+#endif
+
+#if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
+    void* primaryException;
+#endif
+    _Unwind_Exception unwindHeader;
+};
+
+// Verify the negative offsets of different fields.
+static_assert(sizeof(_Unwind_Exception) +
+                      offsetof(__cxa_exception, unwindHeader) ==
+                  sizeof(__cxa_exception),
+              "unwindHeader has wrong negative offsets");
+static_assert(sizeof(_Unwind_Exception) +
+                      offsetof(__cxa_dependent_exception, unwindHeader) ==
+                  sizeof(__cxa_dependent_exception),
+              "unwindHeader has wrong negative offsets");
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+static_assert(offsetof(__cxa_exception, propagationCount) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_exception),
+              "propagationCount has wrong negative offset");
+static_assert(offsetof(__cxa_dependent_exception, propagationCount) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_dependent_exception),
+              "propagationCount has wrong negative offset");
+#elif defined(__LP64__) || defined(_WIN64)
+static_assert(offsetof(__cxa_exception, adjustedPtr) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_exception),
+              "adjustedPtr has wrong negative offset");
+static_assert(offsetof(__cxa_dependent_exception, adjustedPtr) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_dependent_exception),
+              "adjustedPtr has wrong negative offset");
+#else
+static_assert(offsetof(__cxa_exception, referenceCount) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_exception),
+              "referenceCount has wrong negative offset");
+static_assert(offsetof(__cxa_dependent_exception, primaryException) +
+                      sizeof(_Unwind_Exception) + sizeof(void*) ==
+                  sizeof(__cxa_dependent_exception),
+              "primaryException has wrong negative offset");
+#endif
+
+struct _LIBCXXABI_HIDDEN __cxa_eh_globals {
+    __cxa_exception *   caughtExceptions;
+    unsigned int        uncaughtExceptions;
+#if defined(_LIBCXXABI_ARM_EHABI)
+    __cxa_exception* propagatingExceptions;
+#endif
+};
+
+extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals      ();
+extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals_fast ();
+
+extern "C" _LIBCXXABI_FUNC_VIS void * __cxa_allocate_dependent_exception ();
+extern "C" _LIBCXXABI_FUNC_VIS void __cxa_free_dependent_exception (void * dependent_exception);
+
+}  // namespace __cxxabiv1
+
+#endif  // _CXA_EXCEPTION_H
diff --git a/lib/libcxxabi/src/cxa_exception_storage.cpp b/lib/libcxxabi/src/cxa_exception_storage.cpp
new file mode 100644
index 0000000000..24ff55e39d
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_exception_storage.cpp
@@ -0,0 +1,105 @@
+//===--------------------- cxa_exception_storage.cpp ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the storage for the "Caught Exception Stack"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#cxx-exc-stack
+//
+//===----------------------------------------------------------------------===//
+
+#include "cxa_exception.h"
+
+#include <__threading_support>
+
+#if defined(_LIBCXXABI_HAS_NO_THREADS)
+
+namespace __cxxabiv1 {
+extern "C" {
+    static __cxa_eh_globals eh_globals;
+    __cxa_eh_globals *__cxa_get_globals() { return &eh_globals; }
+    __cxa_eh_globals *__cxa_get_globals_fast() { return &eh_globals; }
+    }
+}
+
+#elif defined(HAS_THREAD_LOCAL)
+
+namespace __cxxabiv1 {
+
+namespace {
+    __cxa_eh_globals * __globals () {
+        static thread_local __cxa_eh_globals eh_globals;
+        return &eh_globals;
+        }
+    }
+
+extern "C" {
+    __cxa_eh_globals * __cxa_get_globals      () { return __globals (); }
+    __cxa_eh_globals * __cxa_get_globals_fast () { return __globals (); }
+    }
+}
+
+#else
+
+#include "abort_message.h"
+#include "fallback_malloc.h"
+
+#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+
+//  In general, we treat all threading errors as fatal.
+//  We cannot call std::terminate() because that will in turn
+//  call __cxa_get_globals() and cause infinite recursion.
+
+namespace __cxxabiv1 {
+namespace {
+    std::__libcpp_tls_key key_;
+    std::__libcpp_exec_once_flag flag_ = _LIBCPP_EXEC_ONCE_INITIALIZER;
+
+    void _LIBCPP_TLS_DESTRUCTOR_CC destruct_ (void *p) {
+        __free_with_fallback ( p );
+        if ( 0 != std::__libcpp_tls_set ( key_, NULL ) )
+            abort_message("cannot zero out thread value for __cxa_get_globals()");
+        }
+
+    void construct_ () {
+        if ( 0 != std::__libcpp_tls_create ( &key_, destruct_ ) )
+            abort_message("cannot create thread specific key for __cxa_get_globals()");
+        }
+}
+
+extern "C" {
+    __cxa_eh_globals * __cxa_get_globals () {
+    //  Try to get the globals for this thread
+        __cxa_eh_globals* retVal = __cxa_get_globals_fast ();
+
+    //  If this is the first time we've been asked for these globals, create them
+        if ( NULL == retVal ) {
+            retVal = static_cast<__cxa_eh_globals*>
+                        (__calloc_with_fallback (1, sizeof (__cxa_eh_globals)));
+            if ( NULL == retVal )
+                abort_message("cannot allocate __cxa_eh_globals");
+            if ( 0 != std::__libcpp_tls_set ( key_, retVal ) )
+               abort_message("std::__libcpp_tls_set failure in __cxa_get_globals()");
+           }
+        return retVal;
+        }
+
+    // Note that this implementation will reliably return NULL if not
+    // preceded by a call to __cxa_get_globals().  This is an extension
+    // to the Itanium ABI and is taken advantage of in several places in
+    // libc++abi.
+    __cxa_eh_globals * __cxa_get_globals_fast () {
+    //  First time through, create the key.
+        if (0 != std::__libcpp_execute_once(&flag_, construct_))
+            abort_message("execute once failure in __cxa_get_globals_fast()");
+//        static int init = construct_();
+        return static_cast<__cxa_eh_globals*>(std::__libcpp_tls_get(key_));
+        }
+
+}
+}
+#endif
diff --git a/lib/libcxxabi/src/cxa_guard.cpp b/lib/libcxxabi/src/cxa_guard.cpp
new file mode 100644
index 0000000000..5d1cf235cc
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_guard.cpp
@@ -0,0 +1,53 @@
+//===---------------------------- cxa_guard.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "__cxxabi_config.h"
+#include "cxxabi.h"
+
+// Tell the implementation that we're building the actual implementation
+// (and not testing it)
+#define BUILDING_CXA_GUARD
+#include "cxa_guard_impl.h"
+
+/*
+    This implementation must be careful to not call code external to this file
+    which will turn around and try to call __cxa_guard_acquire reentrantly.
+    For this reason, the headers of this file are as restricted as possible.
+    Previous implementations of this code for __APPLE__ have used
+    std::__libcpp_mutex_lock and the abort_message utility without problem. This
+    implementation also uses std::__libcpp_condvar_wait which has tested
+    to not be a problem.
+*/
+
+namespace __cxxabiv1 {
+
+#if defined(_LIBCXXABI_GUARD_ABI_ARM)
+using guard_type = uint32_t;
+#else
+using guard_type = uint64_t;
+#endif
+
+extern "C"
+{
+_LIBCXXABI_FUNC_VIS int __cxa_guard_acquire(guard_type* raw_guard_object) {
+  SelectedImplementation imp(raw_guard_object);
+  return static_cast<int>(imp.cxa_guard_acquire());
+}
+
+_LIBCXXABI_FUNC_VIS void __cxa_guard_release(guard_type *raw_guard_object) {
+  SelectedImplementation imp(raw_guard_object);
+  imp.cxa_guard_release();
+}
+
+_LIBCXXABI_FUNC_VIS void __cxa_guard_abort(guard_type *raw_guard_object) {
+  SelectedImplementation imp(raw_guard_object);
+  imp.cxa_guard_abort();
+}
+}  // extern "C"
+
+}  // __cxxabiv1
diff --git a/lib/libcxxabi/src/cxa_guard_impl.h b/lib/libcxxabi/src/cxa_guard_impl.h
new file mode 100644
index 0000000000..a8ec0b72fe
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_guard_impl.h
@@ -0,0 +1,567 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef LIBCXXABI_SRC_INCLUDE_CXA_GUARD_IMPL_H
+#define LIBCXXABI_SRC_INCLUDE_CXA_GUARD_IMPL_H
+
+/* cxa_guard_impl.h - Implements the C++ runtime support for function local
+ * static guards.
+ * The layout of the guard object is the same across ARM and Itanium.
+ *
+ * The first "guard byte" (which is checked by the compiler) is set only upon
+ * the completion of cxa release.
+ *
+ * The second "init byte" does the rest of the bookkeeping. It tracks if
+ * initialization is complete or pending, and if there are waiting threads.
+ *
+ * If the guard variable is 64-bits and the platforms supplies a 32-bit thread
+ * identifier, it is used to detect recursive initialization. The thread ID of
+ * the thread currently performing initialization is stored in the second word.
+ *
+ *  Guard Object Layout:
+ * -------------------------------------------------------------------------
+ * |a: guard byte | a+1: init byte | a+2 : unused ... | a+4: thread-id ... |
+ * ------------------------------------------------------------------------
+ *
+ *  Access Protocol:
+ *    For each implementation the guard byte is checked and set before accessing
+ *    the init byte.
+ *
+ *  Overall Design:
+ *    The implementation was designed to allow each implementation to be tested
+ *    independent of the C++ runtime or platform support.
+ *
+ */
+
+#include "__cxxabi_config.h"
+#include "include/atomic_support.h"
+#include <unistd.h>
+#include <sys/types.h>
+#if defined(__has_include)
+# if __has_include(<sys/syscall.h>)
+#   include <sys/syscall.h>
+# endif
+#endif
+
+#include <stdlib.h>
+#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+// To make testing possible, this header is included from both cxa_guard.cpp
+// and a number of tests.
+//
+// For this reason we place everything in an anonymous namespace -- even though
+// we're in a header. We want the actual implementation and the tests to have
+// unique definitions of the types in this header (since the tests may depend
+// on function local statics).
+//
+// To enforce this either `BUILDING_CXA_GUARD` or `TESTING_CXA_GUARD` must be
+// defined when including this file. Only `src/cxa_guard.cpp` should define
+// the former.
+#ifdef BUILDING_CXA_GUARD
+# include "abort_message.h"
+# define ABORT_WITH_MESSAGE(...) ::abort_message(__VA_ARGS__)
+#elif defined(TESTING_CXA_GUARD)
+# define ABORT_WITH_MESSAGE(...) ::abort()
+#else
+# error "Either BUILDING_CXA_GUARD or TESTING_CXA_GUARD must be defined"
+#endif
+
+#if __has_feature(thread_sanitizer)
+extern "C" void __tsan_acquire(void*);
+extern "C" void __tsan_release(void*);
+#else
+#define __tsan_acquire(addr) ((void)0)
+#define __tsan_release(addr) ((void)0)
+#endif
+
+namespace __cxxabiv1 {
+// Use an anonymous namespace to ensure that the tests and actual implementation
+// have unique definitions of these symbols.
+namespace {
+
+//===----------------------------------------------------------------------===//
+//                          Misc Utilities
+//===----------------------------------------------------------------------===//
+
+template <class T, T(*Init)()>
+struct LazyValue {
+  LazyValue() : is_init(false) {}
+
+  T& get() {
+    if (!is_init) {
+      value = Init();
+      is_init = true;
+    }
+    return value;
+  }
+ private:
+  T value;
+  bool is_init = false;
+};
+
+//===----------------------------------------------------------------------===//
+//                       PlatformGetThreadID
+//===----------------------------------------------------------------------===//
+
+#if defined(__APPLE__) && defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
+uint32_t PlatformThreadID() {
+  static_assert(sizeof(mach_port_t) == sizeof(uint32_t), "");
+  return static_cast<uint32_t>(
+      pthread_mach_thread_np(std::__libcpp_thread_get_current_id()));
+}
+#elif defined(SYS_gettid) && defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
+uint32_t PlatformThreadID() {
+  static_assert(sizeof(pid_t) == sizeof(uint32_t), "");
+  return static_cast<uint32_t>(syscall(SYS_gettid));
+}
+#else
+constexpr uint32_t (*PlatformThreadID)() = nullptr;
+#endif
+
+
+constexpr bool PlatformSupportsThreadID() {
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-pointer-compare"
+#endif
+  return +PlatformThreadID != nullptr;
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+//                          GuardBase
+//===----------------------------------------------------------------------===//
+
+enum class AcquireResult {
+  INIT_IS_DONE,
+  INIT_IS_PENDING,
+};
+constexpr AcquireResult INIT_IS_DONE = AcquireResult::INIT_IS_DONE;
+constexpr AcquireResult INIT_IS_PENDING = AcquireResult::INIT_IS_PENDING;
+
+static constexpr uint8_t UNSET = 0;
+static constexpr uint8_t COMPLETE_BIT = (1 << 0);
+static constexpr uint8_t PENDING_BIT = (1 << 1);
+static constexpr uint8_t WAITING_BIT = (1 << 2);
+
+template <class Derived>
+struct GuardObject {
+  GuardObject() = delete;
+  GuardObject(GuardObject const&) = delete;
+  GuardObject& operator=(GuardObject const&) = delete;
+
+  explicit GuardObject(uint32_t* g)
+      : base_address(g), guard_byte_address(reinterpret_cast<uint8_t*>(g)),
+        init_byte_address(reinterpret_cast<uint8_t*>(g) + 1),
+        thread_id_address(nullptr) {}
+
+  explicit GuardObject(uint64_t* g)
+      : base_address(g), guard_byte_address(reinterpret_cast<uint8_t*>(g)),
+        init_byte_address(reinterpret_cast<uint8_t*>(g) + 1),
+        thread_id_address(reinterpret_cast<uint32_t*>(g) + 1) {}
+
+public:
+  /// Implements __cxa_guard_acquire
+  AcquireResult cxa_guard_acquire() {
+    AtomicInt<uint8_t> guard_byte(guard_byte_address);
+    if (guard_byte.load(std::_AO_Acquire) != UNSET)
+      return INIT_IS_DONE;
+    return derived()->acquire_init_byte();
+  }
+
+  /// Implements __cxa_guard_release
+  void cxa_guard_release() {
+    AtomicInt<uint8_t> guard_byte(guard_byte_address);
+    // Store complete first, so that when release wakes other folks, they see
+    // it as having been completed.
+    guard_byte.store(COMPLETE_BIT, std::_AO_Release);
+    derived()->release_init_byte();
+  }
+
+  /// Implements __cxa_guard_abort
+  void cxa_guard_abort() { derived()->abort_init_byte(); }
+
+public:
+  /// base_address - the address of the original guard object.
+  void* const base_address;
+  /// The address of the guord byte at offset 0.
+  uint8_t* const guard_byte_address;
+  /// The address of the byte used by the implementation during initialization.
+  uint8_t* const init_byte_address;
+  /// An optional address storing an identifier for the thread performing initialization.
+  /// It's used to detect recursive initialization.
+  uint32_t* const thread_id_address;
+
+private:
+  Derived* derived() { return static_cast<Derived*>(this); }
+};
+
+//===----------------------------------------------------------------------===//
+//                    Single Threaded Implementation
+//===----------------------------------------------------------------------===//
+
+struct InitByteNoThreads : GuardObject<InitByteNoThreads> {
+  using GuardObject::GuardObject;
+
+  AcquireResult acquire_init_byte() {
+    if (*init_byte_address == COMPLETE_BIT)
+      return INIT_IS_DONE;
+    if (*init_byte_address & PENDING_BIT)
+      ABORT_WITH_MESSAGE("__cxa_guard_acquire detected recursive initialization");
+    *init_byte_address = PENDING_BIT;
+    return INIT_IS_PENDING;
+  }
+
+  void release_init_byte() { *init_byte_address = COMPLETE_BIT; }
+  void abort_init_byte() { *init_byte_address = UNSET; }
+};
+
+
+//===----------------------------------------------------------------------===//
+//                     Global Mutex Implementation
+//===----------------------------------------------------------------------===//
+
+struct LibcppMutex;
+struct LibcppCondVar;
+
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+struct LibcppMutex {
+  LibcppMutex() = default;
+  LibcppMutex(LibcppMutex const&) = delete;
+  LibcppMutex& operator=(LibcppMutex const&) = delete;
+
+  bool lock() { return std::__libcpp_mutex_lock(&mutex); }
+  bool unlock() { return std::__libcpp_mutex_unlock(&mutex); }
+
+private:
+  friend struct LibcppCondVar;
+  std::__libcpp_mutex_t mutex = _LIBCPP_MUTEX_INITIALIZER;
+};
+
+struct LibcppCondVar {
+  LibcppCondVar() = default;
+  LibcppCondVar(LibcppCondVar const&) = delete;
+  LibcppCondVar& operator=(LibcppCondVar const&) = delete;
+
+  bool wait(LibcppMutex& mut) {
+    return std::__libcpp_condvar_wait(&cond, &mut.mutex);
+  }
+  bool broadcast() { return std::__libcpp_condvar_broadcast(&cond); }
+
+private:
+  std::__libcpp_condvar_t cond = _LIBCPP_CONDVAR_INITIALIZER;
+};
+#else
+struct LibcppMutex {};
+struct LibcppCondVar {};
+#endif // !defined(_LIBCXXABI_HAS_NO_THREADS)
+
+
+template <class Mutex, class CondVar, Mutex& global_mutex, CondVar& global_cond,
+          uint32_t (*GetThreadID)() = PlatformThreadID>
+struct InitByteGlobalMutex
+    : GuardObject<InitByteGlobalMutex<Mutex, CondVar, global_mutex, global_cond,
+                                    GetThreadID>> {
+
+  using BaseT = typename InitByteGlobalMutex::GuardObject;
+  using BaseT::BaseT;
+
+  explicit InitByteGlobalMutex(uint32_t *g)
+    : BaseT(g), has_thread_id_support(false) {}
+  explicit InitByteGlobalMutex(uint64_t *g)
+    : BaseT(g), has_thread_id_support(PlatformSupportsThreadID()) {}
+
+public:
+  AcquireResult acquire_init_byte() {
+    LockGuard g("__cxa_guard_acquire");
+    // Check for possible recursive initialization.
+    if (has_thread_id_support && (*init_byte_address & PENDING_BIT)) {
+      if (*thread_id_address == current_thread_id.get())
+       ABORT_WITH_MESSAGE("__cxa_guard_acquire detected recursive initialization");
+    }
+
+    // Wait until the pending bit is not set.
+    while (*init_byte_address & PENDING_BIT) {
+      *init_byte_address |= WAITING_BIT;
+      global_cond.wait(global_mutex);
+    }
+
+    if (*init_byte_address == COMPLETE_BIT)
+      return INIT_IS_DONE;
+
+    if (has_thread_id_support)
+      *thread_id_address = current_thread_id.get();
+
+    *init_byte_address = PENDING_BIT;
+    return INIT_IS_PENDING;
+  }
+
+  void release_init_byte() {
+    bool has_waiting;
+    {
+      LockGuard g("__cxa_guard_release");
+      has_waiting = *init_byte_address & WAITING_BIT;
+      *init_byte_address = COMPLETE_BIT;
+    }
+    if (has_waiting) {
+      if (global_cond.broadcast()) {
+        ABORT_WITH_MESSAGE("%s failed to broadcast", "__cxa_guard_release");
+      }
+    }
+  }
+
+  void abort_init_byte() {
+    bool has_waiting;
+    {
+      LockGuard g("__cxa_guard_abort");
+      if (has_thread_id_support)
+        *thread_id_address = 0;
+      has_waiting = *init_byte_address & WAITING_BIT;
+      *init_byte_address = UNSET;
+    }
+    if (has_waiting) {
+      if (global_cond.broadcast()) {
+        ABORT_WITH_MESSAGE("%s failed to broadcast", "__cxa_guard_abort");
+      }
+    }
+  }
+
+private:
+  using BaseT::init_byte_address;
+  using BaseT::thread_id_address;
+  const bool has_thread_id_support;
+  LazyValue<uint32_t, GetThreadID> current_thread_id;
+
+private:
+  struct LockGuard {
+    LockGuard() = delete;
+    LockGuard(LockGuard const&) = delete;
+    LockGuard& operator=(LockGuard const&) = delete;
+
+    explicit LockGuard(const char* calling_func)
+        : calling_func(calling_func)  {
+      if (global_mutex.lock())
+        ABORT_WITH_MESSAGE("%s failed to acquire mutex", calling_func);
+    }
+
+    ~LockGuard() {
+      if (global_mutex.unlock())
+        ABORT_WITH_MESSAGE("%s failed to release mutex", calling_func);
+    }
+
+  private:
+    const char* const calling_func;
+  };
+};
+
+//===----------------------------------------------------------------------===//
+//                         Futex Implementation
+//===----------------------------------------------------------------------===//
+
+#if defined(SYS_futex)
+void PlatformFutexWait(int* addr, int expect) {
+  constexpr int WAIT = 0;
+  syscall(SYS_futex, addr, WAIT, expect, 0);
+  __tsan_acquire(addr);
+}
+void PlatformFutexWake(int* addr) {
+  constexpr int WAKE = 1;
+  __tsan_release(addr);
+  syscall(SYS_futex, addr, WAKE, INT_MAX);
+}
+#else
+constexpr void (*PlatformFutexWait)(int*, int) = nullptr;
+constexpr void (*PlatformFutexWake)(int*) = nullptr;
+#endif
+
+constexpr bool PlatformSupportsFutex() {
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-pointer-compare"
+#endif
+  return +PlatformFutexWait != nullptr;
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+}
+
+/// InitByteFutex - Manages initialization using atomics and the futex syscall
+/// for waiting and waking.
+template <void (*Wait)(int*, int) = PlatformFutexWait,
+          void (*Wake)(int*) = PlatformFutexWake,
+          uint32_t (*GetThreadIDArg)() = PlatformThreadID>
+struct InitByteFutex : GuardObject<InitByteFutex<Wait, Wake, GetThreadIDArg>> {
+  using BaseT = typename InitByteFutex::GuardObject;
+
+  /// ARM Constructor
+  explicit InitByteFutex(uint32_t *g) : BaseT(g),
+    init_byte(this->init_byte_address),
+    has_thread_id_support(this->thread_id_address && GetThreadIDArg),
+    thread_id(this->thread_id_address) {}
+
+  /// Itanium Constructor
+  explicit InitByteFutex(uint64_t *g) : BaseT(g),
+    init_byte(this->init_byte_address),
+    has_thread_id_support(this->thread_id_address && GetThreadIDArg),
+    thread_id(this->thread_id_address) {}
+
+public:
+  AcquireResult acquire_init_byte() {
+    while (true) {
+      uint8_t last_val = UNSET;
+      if (init_byte.compare_exchange(&last_val, PENDING_BIT, std::_AO_Acq_Rel,
+                                     std::_AO_Acquire)) {
+        if (has_thread_id_support) {
+          thread_id.store(current_thread_id.get(), std::_AO_Relaxed);
+        }
+        return INIT_IS_PENDING;
+      }
+
+      if (last_val == COMPLETE_BIT)
+        return INIT_IS_DONE;
+
+      if (last_val & PENDING_BIT) {
+
+        // Check for recursive initialization
+        if (has_thread_id_support && thread_id.load(std::_AO_Relaxed) == current_thread_id.get()) {
+            ABORT_WITH_MESSAGE("__cxa_guard_acquire detected recursive initialization");
+        }
+
+        if ((last_val & WAITING_BIT) == 0) {
+          // This compare exchange can fail for several reasons
+          // (1) another thread finished the whole thing before we got here
+          // (2) another thread set the waiting bit we were trying to thread
+          // (3) another thread had an exception and failed to finish
+          if (!init_byte.compare_exchange(&last_val, PENDING_BIT | WAITING_BIT,
+                                          std::_AO_Acq_Rel, std::_AO_Release)) {
+            // (1) success, via someone else's work!
+            if (last_val == COMPLETE_BIT)
+              return INIT_IS_DONE;
+
+            // (3) someone else, bailed on doing the work, retry from the start!
+            if (last_val == UNSET)
+              continue;
+
+            // (2) the waiting bit got set, so we are happy to keep waiting
+          }
+        }
+        wait_on_initialization();
+      }
+    }
+  }
+
+  void release_init_byte() {
+    uint8_t old = init_byte.exchange(COMPLETE_BIT, std::_AO_Acq_Rel);
+    if (old & WAITING_BIT)
+      wake_all();
+  }
+
+  void abort_init_byte() {
+    if (has_thread_id_support)
+      thread_id.store(0, std::_AO_Relaxed);
+
+    uint8_t old = init_byte.exchange(0, std::_AO_Acq_Rel);
+    if (old & WAITING_BIT)
+      wake_all();
+  }
+
+private:
+  /// Use the futex to wait on the current guard variable. Futex expects a
+  /// 32-bit 4-byte aligned address as the first argument, so we have to use use
+  /// the base address of the guard variable (not the init byte).
+  void wait_on_initialization() {
+    Wait(static_cast<int*>(this->base_address),
+         expected_value_for_futex(PENDING_BIT | WAITING_BIT));
+  }
+  void wake_all() { Wake(static_cast<int*>(this->base_address)); }
+
+private:
+  AtomicInt<uint8_t> init_byte;
+
+  const bool has_thread_id_support;
+  // Unsafe to use unless has_thread_id_support
+  AtomicInt<uint32_t> thread_id;
+  LazyValue<uint32_t, GetThreadIDArg> current_thread_id;
+
+  /// Create the expected integer value for futex `wait(int* addr, int expected)`.
+  /// We pass the base address as the first argument, So this function creates
+  /// an zero-initialized integer  with `b` copied at the correct offset.
+  static int expected_value_for_futex(uint8_t b) {
+    int dest_val = 0;
+    std::memcpy(reinterpret_cast<char*>(&dest_val) + 1, &b, 1);
+    return dest_val;
+  }
+
+  static_assert(Wait != nullptr && Wake != nullptr, "");
+};
+
+//===----------------------------------------------------------------------===//
+//
+//===----------------------------------------------------------------------===//
+
+template <class T>
+struct GlobalStatic {
+  static T instance;
+};
+template <class T>
+_LIBCPP_SAFE_STATIC T GlobalStatic<T>::instance = {};
+
+enum class Implementation {
+  NoThreads,
+  GlobalLock,
+  Futex
+};
+
+template <Implementation Impl>
+struct SelectImplementation;
+
+template <>
+struct SelectImplementation<Implementation::NoThreads> {
+  using type = InitByteNoThreads;
+};
+
+template <>
+struct SelectImplementation<Implementation::GlobalLock> {
+  using type = InitByteGlobalMutex<
+      LibcppMutex, LibcppCondVar, GlobalStatic<LibcppMutex>::instance,
+      GlobalStatic<LibcppCondVar>::instance, PlatformThreadID>;
+};
+
+template <>
+struct SelectImplementation<Implementation::Futex> {
+  using type =
+      InitByteFutex<PlatformFutexWait, PlatformFutexWake, PlatformThreadID>;
+};
+
+// TODO(EricWF): We should prefer the futex implementation when available. But
+// it should be done in a separate step from adding the implementation.
+constexpr Implementation CurrentImplementation =
+#if defined(_LIBCXXABI_HAS_NO_THREADS)
+    Implementation::NoThreads;
+#elif defined(_LIBCXXABI_USE_FUTEX)
+    Implementation::Futex;
+#else
+   Implementation::GlobalLock;
+#endif
+
+static_assert(CurrentImplementation != Implementation::Futex
+           || PlatformSupportsFutex(), "Futex selected but not supported");
+
+using SelectedImplementation =
+    SelectImplementation<CurrentImplementation>::type;
+
+} // end namespace
+} // end namespace __cxxabiv1
+
+#endif // LIBCXXABI_SRC_INCLUDE_CXA_GUARD_IMPL_H
diff --git a/lib/libcxxabi/src/cxa_handlers.cpp b/lib/libcxxabi/src/cxa_handlers.cpp
new file mode 100644
index 0000000000..f520a4db6e
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_handlers.cpp
@@ -0,0 +1,111 @@
+//===------------------------- cxa_handlers.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+// This file implements the functionality associated with the terminate_handler,
+//   unexpected_handler, and new_handler.
+//===----------------------------------------------------------------------===//
+
+#include <stdexcept>
+#include <new>
+#include <exception>
+#include "abort_message.h"
+#include "cxxabi.h"
+#include "cxa_handlers.h"
+#include "cxa_exception.h"
+#include "private_typeinfo.h"
+#include "include/atomic_support.h"
+
+namespace std
+{
+
+unexpected_handler
+get_unexpected() _NOEXCEPT
+{
+    return __libcpp_atomic_load(&__cxa_unexpected_handler, _AO_Acquire);
+}
+
+void
+__unexpected(unexpected_handler func)
+{
+    func();
+    // unexpected handler should not return
+    abort_message("unexpected_handler unexpectedly returned");
+}
+
+__attribute__((noreturn))
+void
+unexpected()
+{
+    __unexpected(get_unexpected());
+}
+
+terminate_handler
+get_terminate() _NOEXCEPT
+{
+    return __libcpp_atomic_load(&__cxa_terminate_handler, _AO_Acquire);
+}
+
+void
+__terminate(terminate_handler func) _NOEXCEPT
+{
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCXXABI_NO_EXCEPTIONS
+        func();
+        // handler should not return
+        abort_message("terminate_handler unexpectedly returned");
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        // handler should not throw exception
+        abort_message("terminate_handler unexpectedly threw an exception");
+    }
+#endif  // _LIBCXXABI_NO_EXCEPTIONS
+}
+
+__attribute__((noreturn))
+void
+terminate() _NOEXCEPT
+{
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+    // If there might be an uncaught exception
+    using namespace __cxxabiv1;
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (globals)
+    {
+        __cxa_exception* exception_header = globals->caughtExceptions;
+        if (exception_header)
+        {
+            _Unwind_Exception* unwind_exception =
+                reinterpret_cast<_Unwind_Exception*>(exception_header + 1) - 1;
+            if (__isOurExceptionClass(unwind_exception))
+                __terminate(exception_header->terminateHandler);
+        }
+    }
+#endif
+    __terminate(get_terminate());
+}
+
+extern "C" {
+new_handler __cxa_new_handler = 0;
+}
+
+new_handler
+set_new_handler(new_handler handler) _NOEXCEPT
+{
+    return __libcpp_atomic_exchange(&__cxa_new_handler, handler, _AO_Acq_Rel);
+}
+
+new_handler
+get_new_handler() _NOEXCEPT
+{
+    return __libcpp_atomic_load(&__cxa_new_handler, _AO_Acquire);
+}
+
+}  // std
diff --git a/lib/libcxxabi/src/cxa_handlers.h b/lib/libcxxabi/src/cxa_handlers.h
new file mode 100644
index 0000000000..c8e2e44aee
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_handlers.h
@@ -0,0 +1,55 @@
+//===------------------------- cxa_handlers.h -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+// This file implements the functionality associated with the terminate_handler,
+//   unexpected_handler, and new_handler.
+//===----------------------------------------------------------------------===//
+
+#ifndef _CXA_HANDLERS_H
+#define _CXA_HANDLERS_H
+
+#include <__cxxabi_config.h>
+
+#include <exception>
+
+namespace std
+{
+
+_LIBCXXABI_HIDDEN _LIBCXXABI_NORETURN
+void
+__unexpected(unexpected_handler func);
+
+_LIBCXXABI_HIDDEN _LIBCXXABI_NORETURN
+void
+__terminate(terminate_handler func) _NOEXCEPT;
+
+}  // std
+
+extern "C"
+{
+
+_LIBCXXABI_DATA_VIS extern void (*__cxa_terminate_handler)();
+_LIBCXXABI_DATA_VIS extern void (*__cxa_unexpected_handler)();
+_LIBCXXABI_DATA_VIS extern void (*__cxa_new_handler)();
+
+/*
+
+    At some point in the future these three symbols will become
+    C++11 atomic variables:
+
+    extern std::atomic<std::terminate_handler>  __cxa_terminate_handler;
+    extern std::atomic<std::unexpected_handler> __cxa_unexpected_handler;
+    extern std::atomic<std::new_handler>        __cxa_new_handler;
+
+    This change will not impact their ABI.  But it will allow for a
+    portable performance optimization.
+
+*/
+
+} // extern "C"
+
+#endif  // _CXA_HANDLERS_H
diff --git a/lib/libcxxabi/src/cxa_noexception.cpp b/lib/libcxxabi/src/cxa_noexception.cpp
new file mode 100644
index 0000000000..73e0b2ae03
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_noexception.cpp
@@ -0,0 +1,59 @@
+//===------------------------- cxa_exception.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Exception Handling APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+//===----------------------------------------------------------------------===//
+
+// Support functions for the no-exceptions libc++ library
+
+#include "cxxabi.h"
+
+#include <exception>        // for std::terminate
+#include "cxa_exception.h"
+#include "cxa_handlers.h"
+
+namespace __cxxabiv1 {
+
+extern "C" {
+
+void
+__cxa_increment_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != nullptr)
+        std::terminate();
+}
+
+void
+__cxa_decrement_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != nullptr)
+      std::terminate();
+}
+
+
+void *__cxa_current_primary_exception() throw() { return nullptr; }
+
+void
+__cxa_rethrow_primary_exception(void* thrown_object) {
+    if (thrown_object != nullptr)
+      std::terminate();
+}
+
+bool
+__cxa_uncaught_exception() throw() { return false; }
+
+unsigned int
+__cxa_uncaught_exceptions() throw() { return 0; }
+
+}  // extern "C"
+
+// provide dummy implementations for the 'no exceptions' case.
+uint64_t __getExceptionClass  (const _Unwind_Exception*)           { return 0; }
+void     __setExceptionClass  (      _Unwind_Exception*, uint64_t) {}
+bool     __isOurExceptionClass(const _Unwind_Exception*)           { return false; }
+
+}  // abi
diff --git a/lib/libcxxabi/src/cxa_personality.cpp b/lib/libcxxabi/src/cxa_personality.cpp
new file mode 100644
index 0000000000..f276257761
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_personality.cpp
@@ -0,0 +1,1324 @@
+//===------------------------- cxa_exception.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Exception Handling APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//  http://www.intel.com/design/itanium/downloads/245358.htm
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <typeinfo>
+
+#include "__cxxabi_config.h"
+#include "cxa_exception.h"
+#include "cxa_handlers.h"
+#include "private_typeinfo.h"
+#include "unwind.h"
+
+#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
+#include <windows.h>
+#include <winnt.h>
+
+extern "C" EXCEPTION_DISPOSITION _GCC_specific_handler(PEXCEPTION_RECORD,
+                                                       void *, PCONTEXT,
+                                                       PDISPATCHER_CONTEXT,
+                                                       _Unwind_Personality_Fn);
+#endif
+
+/*
+    Exception Header Layout:
+
++---------------------------+-----------------------------+---------------+
+| __cxa_exception           | _Unwind_Exception CLNGC++\0 | thrown object |
++---------------------------+-----------------------------+---------------+
+                                                          ^
+                                                          |
+  +-------------------------------------------------------+
+  |
++---------------------------+-----------------------------+
+| __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 |
++---------------------------+-----------------------------+
+
+    Exception Handling Table Layout:
+
++-----------------+--------+
+| lpStartEncoding | (char) |
++---------+-------+--------+---------------+-----------------------+
+| lpStart | (encoded with lpStartEncoding) | defaults to funcStart |
++---------+-----+--------+-----------------+---------------+-------+
+| ttypeEncoding | (char) | Encoding of the type_info table |
++---------------+-+------+----+----------------------------+----------------+
+| classInfoOffset | (ULEB128) | Offset to type_info table, defaults to null |
++-----------------++--------+-+----------------------------+----------------+
+| callSiteEncoding | (char) | Encoding for Call Site Table |
++------------------+--+-----+-----+------------------------+--------------------------+
+| callSiteTableLength | (ULEB128) | Call Site Table length, used to find Action table |
++---------------------+-----------+---------------------------------------------------+
+#ifndef __USING_SJLJ_EXCEPTIONS__
++---------------------+-----------+------------------------------------------------+
+| Beginning of Call Site Table            The current ip lies within the           |
+| ...                                     (start, length) range of one of these    |
+|                                         call sites. There may be action needed.  |
+| +-------------+---------------------------------+------------------------------+ |
+| | start       | (encoded with callSiteEncoding) | offset relative to funcStart | |
+| | length      | (encoded with callSiteEncoding) | length of code fragment      | |
+| | landingPad  | (encoded with callSiteEncoding) | offset relative to lpStart   | |
+| | actionEntry | (ULEB128)                       | Action Table Index 1-based   | |
+| |             |                                 | actionEntry == 0 -> cleanup  | |
+| +-------------+---------------------------------+------------------------------+ |
+| ...                                                                              |
++----------------------------------------------------------------------------------+
+#else  // __USING_SJLJ_EXCEPTIONS__
++---------------------+-----------+------------------------------------------------+
+| Beginning of Call Site Table            The current ip is a 1-based index into   |
+| ...                                     this table.  Or it is -1 meaning no      |
+|                                         action is needed.  Or it is 0 meaning    |
+|                                         terminate.                               |
+| +-------------+---------------------------------+------------------------------+ |
+| | landingPad  | (ULEB128)                       | offset relative to lpStart   | |
+| | actionEntry | (ULEB128)                       | Action Table Index 1-based   | |
+| |             |                                 | actionEntry == 0 -> cleanup  | |
+| +-------------+---------------------------------+------------------------------+ |
+| ...                                                                              |
++----------------------------------------------------------------------------------+
+#endif  // __USING_SJLJ_EXCEPTIONS__
++---------------------------------------------------------------------+
+| Beginning of Action Table       ttypeIndex == 0 : cleanup           |
+| ...                             ttypeIndex  > 0 : catch             |
+|                                 ttypeIndex  < 0 : exception spec    |
+| +--------------+-----------+--------------------------------------+ |
+| | ttypeIndex   | (SLEB128) | Index into type_info Table (1-based) | |
+| | actionOffset | (SLEB128) | Offset into next Action Table entry  | |
+| +--------------+-----------+--------------------------------------+ |
+| ...                                                                 |
++---------------------------------------------------------------------+-----------------+
+| type_info Table, but classInfoOffset does *not* point here!                           |
+| +----------------+------------------------------------------------+-----------------+ |
+| | Nth type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == N | |
+| +----------------+------------------------------------------------+-----------------+ |
+| ...                                                                                   |
+| +----------------+------------------------------------------------+-----------------+ |
+| | 1st type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == 1 | |
+| +----------------+------------------------------------------------+-----------------+ |
+| +---------------------------------------+-----------+------------------------------+  |
+| | 1st ttypeIndex for 1st exception spec | (ULEB128) | classInfoOffset points here! |  |
+| | ...                                   | (ULEB128) |                              |  |
+| | Mth ttypeIndex for 1st exception spec | (ULEB128) |                              |  |
+| | 0                                     | (ULEB128) |                              |  |
+| +---------------------------------------+------------------------------------------+  |
+| ...                                                                                   |
+| +---------------------------------------+------------------------------------------+  |
+| | 0                                     | (ULEB128) | throw()                      |  |
+| +---------------------------------------+------------------------------------------+  |
+| ...                                                                                   |
+| +---------------------------------------+------------------------------------------+  |
+| | 1st ttypeIndex for Nth exception spec | (ULEB128) |                              |  |
+| | ...                                   | (ULEB128) |                              |  |
+| | Mth ttypeIndex for Nth exception spec | (ULEB128) |                              |  |
+| | 0                                     | (ULEB128) |                              |  |
+| +---------------------------------------+------------------------------------------+  |
++---------------------------------------------------------------------------------------+
+
+Notes:
+
+*  ttypeIndex in the Action Table, and in the exception spec table, is an index,
+     not a byte count, if positive.  It is a negative index offset of
+     classInfoOffset and the sizeof entry depends on ttypeEncoding.
+   But if ttypeIndex is negative, it is a positive 1-based byte offset into the
+     type_info Table.
+   And if ttypeIndex is zero, it refers to a catch (...).
+
+*  landingPad can be 0, this implies there is nothing to be done.
+
+*  landingPad != 0 and actionEntry == 0 implies a cleanup needs to be done
+     @landingPad.
+
+*  A cleanup can also be found under landingPad != 0 and actionEntry != 0 in
+     the Action Table with ttypeIndex == 0.
+*/
+
+namespace __cxxabiv1
+{
+
+namespace
+{
+
+template <class AsType>
+uintptr_t readPointerHelper(const uint8_t*& p) {
+    AsType value;
+    memcpy(&value, p, sizeof(AsType));
+    p += sizeof(AsType);
+    return static_cast<uintptr_t>(value);
+}
+
+} // end namespace
+
+extern "C"
+{
+
+// private API
+
+// Heavily borrowed from llvm/examples/ExceptionDemo/ExceptionDemo.cpp
+
+// DWARF Constants
+enum
+{
+    DW_EH_PE_absptr   = 0x00,
+    DW_EH_PE_uleb128  = 0x01,
+    DW_EH_PE_udata2   = 0x02,
+    DW_EH_PE_udata4   = 0x03,
+    DW_EH_PE_udata8   = 0x04,
+    DW_EH_PE_sleb128  = 0x09,
+    DW_EH_PE_sdata2   = 0x0A,
+    DW_EH_PE_sdata4   = 0x0B,
+    DW_EH_PE_sdata8   = 0x0C,
+    DW_EH_PE_pcrel    = 0x10,
+    DW_EH_PE_textrel  = 0x20,
+    DW_EH_PE_datarel  = 0x30,
+    DW_EH_PE_funcrel  = 0x40,
+    DW_EH_PE_aligned  = 0x50,
+    DW_EH_PE_indirect = 0x80,
+    DW_EH_PE_omit     = 0xFF
+};
+
+/// Read a uleb128 encoded value and advance pointer
+/// See Variable Length Data Appendix C in:
+/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @returns decoded value
+static
+uintptr_t
+readULEB128(const uint8_t** data)
+{
+    uintptr_t result = 0;
+    uintptr_t shift = 0;
+    unsigned char byte;
+    const uint8_t *p = *data;
+    do
+    {
+        byte = *p++;
+        result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
+        shift += 7;
+    } while (byte & 0x80);
+    *data = p;
+    return result;
+}
+
+/// Read a sleb128 encoded value and advance pointer
+/// See Variable Length Data Appendix C in:
+/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @returns decoded value
+static
+intptr_t
+readSLEB128(const uint8_t** data)
+{
+    uintptr_t result = 0;
+    uintptr_t shift = 0;
+    unsigned char byte;
+    const uint8_t *p = *data;
+    do
+    {
+        byte = *p++;
+        result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
+        shift += 7;
+    } while (byte & 0x80);
+    *data = p;
+    if ((byte & 0x40) && (shift < (sizeof(result) << 3)))
+        result |= static_cast<uintptr_t>(~0) << shift;
+    return static_cast<intptr_t>(result);
+}
+
+/// Read a pointer encoded value and advance pointer
+/// See Variable Length Data in:
+/// @link http://dwarfstd.org/Dwarf3.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @param encoding dwarf encoding type
+/// @returns decoded value
+static
+uintptr_t
+readEncodedPointer(const uint8_t** data, uint8_t encoding)
+{
+    uintptr_t result = 0;
+    if (encoding == DW_EH_PE_omit)
+        return result;
+    const uint8_t* p = *data;
+    // first get value
+    switch (encoding & 0x0F)
+    {
+    case DW_EH_PE_absptr:
+        result = readPointerHelper<uintptr_t>(p);
+        break;
+    case DW_EH_PE_uleb128:
+        result = readULEB128(&p);
+        break;
+    case DW_EH_PE_sleb128:
+        result = static_cast<uintptr_t>(readSLEB128(&p));
+        break;
+    case DW_EH_PE_udata2:
+        result = readPointerHelper<uint16_t>(p);
+        break;
+    case DW_EH_PE_udata4:
+        result = readPointerHelper<uint32_t>(p);
+        break;
+    case DW_EH_PE_udata8:
+        result = readPointerHelper<uint64_t>(p);
+        break;
+    case DW_EH_PE_sdata2:
+        result = readPointerHelper<int16_t>(p);
+        break;
+    case DW_EH_PE_sdata4:
+        result = readPointerHelper<int32_t>(p);
+        break;
+    case DW_EH_PE_sdata8:
+        result = readPointerHelper<int64_t>(p);
+        break;
+    default:
+        // not supported
+        abort();
+        break;
+    }
+    // then add relative offset
+    switch (encoding & 0x70)
+    {
+    case DW_EH_PE_absptr:
+        // do nothing
+        break;
+    case DW_EH_PE_pcrel:
+        if (result)
+            result += (uintptr_t)(*data);
+        break;
+    case DW_EH_PE_textrel:
+    case DW_EH_PE_datarel:
+    case DW_EH_PE_funcrel:
+    case DW_EH_PE_aligned:
+    default:
+        // not supported
+        abort();
+        break;
+    }
+    // then apply indirection
+    if (result && (encoding & DW_EH_PE_indirect))
+        result = *((uintptr_t*)result);
+    *data = p;
+    return result;
+}
+
+static
+void
+call_terminate(bool native_exception, _Unwind_Exception* unwind_exception)
+{
+    __cxa_begin_catch(unwind_exception);
+    if (native_exception)
+    {
+        // Use the stored terminate_handler if possible
+        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+        std::__terminate(exception_header->terminateHandler);
+    }
+    std::terminate();
+}
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+static const void* read_target2_value(const void* ptr)
+{
+    uintptr_t offset = *reinterpret_cast<const uintptr_t*>(ptr);
+    if (!offset)
+        return 0;
+    // "ARM EABI provides a TARGET2 relocation to describe these typeinfo
+    // pointers. The reason being it allows their precise semantics to be
+    // deferred to the linker. For bare-metal they turn into absolute
+    // relocations. For linux they turn into GOT-REL relocations."
+    // https://gcc.gnu.org/ml/gcc-patches/2009-08/msg00264.html
+#if defined(LIBCXXABI_BAREMETAL)
+    return reinterpret_cast<const void*>(reinterpret_cast<uintptr_t>(ptr) +
+                                         offset);
+#else
+    return *reinterpret_cast<const void **>(reinterpret_cast<uintptr_t>(ptr) +
+                                            offset);
+#endif
+}
+
+static const __shim_type_info*
+get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo,
+                   uint8_t ttypeEncoding, bool native_exception,
+                   _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.  Indicates corrupted eh_table.
+        call_terminate(native_exception, unwind_exception);
+    }
+
+    assert(((ttypeEncoding == DW_EH_PE_absptr) ||  // LLVM or GCC 4.6
+            (ttypeEncoding == DW_EH_PE_pcrel) ||  // GCC 4.7 baremetal
+            (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) &&  // GCC 4.7 linux
+           "Unexpected TTypeEncoding");
+    (void)ttypeEncoding;
+
+    const uint8_t* ttypePtr = classInfo - ttypeIndex * sizeof(uintptr_t);
+    return reinterpret_cast<const __shim_type_info *>(
+        read_target2_value(ttypePtr));
+}
+#else // !defined(_LIBCXXABI_ARM_EHABI)
+static
+const __shim_type_info*
+get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo,
+                   uint8_t ttypeEncoding, bool native_exception,
+                   _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.  Indicates corrupted eh_table.
+        call_terminate(native_exception, unwind_exception);
+    }
+    switch (ttypeEncoding & 0x0F)
+    {
+    case DW_EH_PE_absptr:
+        ttypeIndex *= sizeof(void*);
+        break;
+    case DW_EH_PE_udata2:
+    case DW_EH_PE_sdata2:
+        ttypeIndex *= 2;
+        break;
+    case DW_EH_PE_udata4:
+    case DW_EH_PE_sdata4:
+        ttypeIndex *= 4;
+        break;
+    case DW_EH_PE_udata8:
+    case DW_EH_PE_sdata8:
+        ttypeIndex *= 8;
+        break;
+    default:
+        // this should not happen.   Indicates corrupted eh_table.
+        call_terminate(native_exception, unwind_exception);
+    }
+    classInfo -= ttypeIndex;
+    return (const __shim_type_info*)readEncodedPointer(&classInfo, ttypeEncoding);
+}
+#endif // !defined(_LIBCXXABI_ARM_EHABI)
+
+/*
+    This is checking a thrown exception type, excpType, against a possibly empty
+    list of catchType's which make up an exception spec.
+
+    An exception spec acts like a catch handler, but in reverse.  This "catch
+    handler" will catch an excpType if and only if none of the catchType's in
+    the list will catch a excpType.  If any catchType in the list can catch an
+    excpType, then this exception spec does not catch the excpType.
+*/
+#if defined(_LIBCXXABI_ARM_EHABI)
+static
+bool
+exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo,
+                         uint8_t ttypeEncoding, const __shim_type_info* excpType,
+                         void* adjustedPtr, _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.   Indicates corrupted eh_table.
+        call_terminate(false, unwind_exception);
+    }
+
+    assert(((ttypeEncoding == DW_EH_PE_absptr) ||  // LLVM or GCC 4.6
+            (ttypeEncoding == DW_EH_PE_pcrel) ||  // GCC 4.7 baremetal
+            (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) &&  // GCC 4.7 linux
+           "Unexpected TTypeEncoding");
+    (void)ttypeEncoding;
+
+    // specIndex is negative of 1-based byte offset into classInfo;
+    specIndex = -specIndex;
+    --specIndex;
+    const void** temp = reinterpret_cast<const void**>(
+        reinterpret_cast<uintptr_t>(classInfo) +
+        static_cast<uintptr_t>(specIndex) * sizeof(uintptr_t));
+    // If any type in the spec list can catch excpType, return false, else return true
+    //    adjustments to adjustedPtr are ignored.
+    while (true)
+    {
+        // ARM EHABI exception specification table (filter table) consists of
+        // several pointers which will directly point to the type info object
+        // (instead of ttypeIndex).  The table will be terminated with 0.
+        const void** ttypePtr = temp++;
+        if (*ttypePtr == 0)
+            break;
+        // We can get the __shim_type_info simply by performing a
+        // R_ARM_TARGET2 relocation, and cast the result to __shim_type_info.
+        const __shim_type_info* catchType =
+            static_cast<const __shim_type_info*>(read_target2_value(ttypePtr));
+        void* tempPtr = adjustedPtr;
+        if (catchType->can_catch(excpType, tempPtr))
+            return false;
+    }
+    return true;
+}
+#else
+static
+bool
+exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo,
+                         uint8_t ttypeEncoding, const __shim_type_info* excpType,
+                         void* adjustedPtr, _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.   Indicates corrupted eh_table.
+        call_terminate(false, unwind_exception);
+    }
+    // specIndex is negative of 1-based byte offset into classInfo;
+    specIndex = -specIndex;
+    --specIndex;
+    const uint8_t* temp = classInfo + specIndex;
+    // If any type in the spec list can catch excpType, return false, else return true
+    //    adjustments to adjustedPtr are ignored.
+    while (true)
+    {
+        uint64_t ttypeIndex = readULEB128(&temp);
+        if (ttypeIndex == 0)
+            break;
+        const __shim_type_info* catchType = get_shim_type_info(ttypeIndex,
+                                                               classInfo,
+                                                               ttypeEncoding,
+                                                               true,
+                                                               unwind_exception);
+        void* tempPtr = adjustedPtr;
+        if (catchType->can_catch(excpType, tempPtr))
+            return false;
+    }
+    return true;
+}
+#endif
+
+static
+void*
+get_thrown_object_ptr(_Unwind_Exception* unwind_exception)
+{
+    // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1
+    //    Regardless, this library is prohibited from touching a foreign exception
+    void* adjustedPtr = unwind_exception + 1;
+    if (__getExceptionClass(unwind_exception) == kOurDependentExceptionClass)
+        adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException;
+    return adjustedPtr;
+}
+
+namespace
+{
+
+struct scan_results
+{
+    int64_t        ttypeIndex;   // > 0 catch handler, < 0 exception spec handler, == 0 a cleanup
+    const uint8_t* actionRecord;         // Currently unused.  Retained to ease future maintenance.
+    const uint8_t* languageSpecificData;  // Needed only for __cxa_call_unexpected
+    uintptr_t      landingPad;   // null -> nothing found, else something found
+    void*          adjustedPtr;  // Used in cxa_exception.cpp
+    _Unwind_Reason_Code reason;  // One of _URC_FATAL_PHASE1_ERROR,
+                                 //        _URC_FATAL_PHASE2_ERROR,
+                                 //        _URC_CONTINUE_UNWIND,
+                                 //        _URC_HANDLER_FOUND
+};
+
+}  // unnamed namespace
+
+static
+void
+set_registers(_Unwind_Exception* unwind_exception, _Unwind_Context* context,
+              const scan_results& results)
+{
+#if defined(__USING_SJLJ_EXCEPTIONS__)
+#define __builtin_eh_return_data_regno(regno) regno
+#endif
+  _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
+                reinterpret_cast<uintptr_t>(unwind_exception));
+  _Unwind_SetGR(context, __builtin_eh_return_data_regno(1),
+                static_cast<uintptr_t>(results.ttypeIndex));
+  _Unwind_SetIP(context, results.landingPad);
+}
+
+/*
+    There are 3 types of scans needed:
+
+    1.  Scan for handler with native or foreign exception.  If handler found,
+        save state and return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
+        May also report an error on invalid input.
+        May terminate for invalid exception table.
+        _UA_SEARCH_PHASE
+
+    2.  Scan for handler with foreign exception.  Must return _URC_HANDLER_FOUND,
+        or call terminate.
+        _UA_CLEANUP_PHASE && _UA_HANDLER_FRAME && !native_exception
+
+    3.  Scan for cleanups.  If a handler is found and this isn't forced unwind,
+        then terminate, otherwise ignore the handler and keep looking for cleanup.
+        If a cleanup is found, return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
+        May also report an error on invalid input.
+        May terminate for invalid exception table.
+        _UA_CLEANUP_PHASE && !_UA_HANDLER_FRAME
+*/
+
+static void scan_eh_tab(scan_results &results, _Unwind_Action actions,
+                        bool native_exception,
+                        _Unwind_Exception *unwind_exception,
+                        _Unwind_Context *context) {
+    // Initialize results to found nothing but an error
+    results.ttypeIndex = 0;
+    results.actionRecord = 0;
+    results.languageSpecificData = 0;
+    results.landingPad = 0;
+    results.adjustedPtr = 0;
+    results.reason = _URC_FATAL_PHASE1_ERROR;
+    // Check for consistent actions
+    if (actions & _UA_SEARCH_PHASE)
+    {
+        // Do Phase 1
+        if (actions & (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME | _UA_FORCE_UNWIND))
+        {
+            // None of these flags should be set during Phase 1
+            //   Client error
+            results.reason = _URC_FATAL_PHASE1_ERROR;
+            return;
+        }
+    }
+    else if (actions & _UA_CLEANUP_PHASE)
+    {
+        if ((actions & _UA_HANDLER_FRAME) && (actions & _UA_FORCE_UNWIND))
+        {
+            // _UA_HANDLER_FRAME should only be set if phase 1 found a handler.
+            // If _UA_FORCE_UNWIND is set, phase 1 shouldn't have happened.
+            //    Client error
+            results.reason = _URC_FATAL_PHASE2_ERROR;
+            return;
+        }
+    }
+    else // Neither _UA_SEARCH_PHASE nor _UA_CLEANUP_PHASE is set
+    {
+        // One of these should be set.
+        //   Client error
+        results.reason = _URC_FATAL_PHASE1_ERROR;
+        return;
+    }
+    // Start scan by getting exception table address
+    const uint8_t *lsda = (const uint8_t *)_Unwind_GetLanguageSpecificData(context);
+    if (lsda == 0)
+    {
+        // There is no exception table
+        results.reason = _URC_CONTINUE_UNWIND;
+        return;
+    }
+    results.languageSpecificData = lsda;
+    // Get the current instruction pointer and offset it before next
+    // instruction in the current frame which threw the exception.
+    uintptr_t ip = _Unwind_GetIP(context) - 1;
+    // Get beginning current frame's code (as defined by the
+    // emitted dwarf code)
+    uintptr_t funcStart = _Unwind_GetRegionStart(context);
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    if (ip == uintptr_t(-1))
+    {
+        // no action
+        results.reason = _URC_CONTINUE_UNWIND;
+        return;
+    }
+    else if (ip == 0)
+        call_terminate(native_exception, unwind_exception);
+    // ip is 1-based index into call site table
+#else  // !__USING_SJLJ_EXCEPTIONS__
+    uintptr_t ipOffset = ip - funcStart;
+#endif  // !defined(_USING_SLJL_EXCEPTIONS__)
+    const uint8_t* classInfo = NULL;
+    // Note: See JITDwarfEmitter::EmitExceptionTable(...) for corresponding
+    //       dwarf emission
+    // Parse LSDA header.
+    uint8_t lpStartEncoding = *lsda++;
+    const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding);
+    if (lpStart == 0)
+        lpStart = (const uint8_t*)funcStart;
+    uint8_t ttypeEncoding = *lsda++;
+    if (ttypeEncoding != DW_EH_PE_omit)
+    {
+        // Calculate type info locations in emitted dwarf code which
+        // were flagged by type info arguments to llvm.eh.selector
+        // intrinsic
+        uintptr_t classInfoOffset = readULEB128(&lsda);
+        classInfo = lsda + classInfoOffset;
+    }
+    // Walk call-site table looking for range that
+    // includes current PC.
+    uint8_t callSiteEncoding = *lsda++;
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    (void)callSiteEncoding;  // When using SjLj exceptions, callSiteEncoding is never used
+#endif
+    uint32_t callSiteTableLength = static_cast<uint32_t>(readULEB128(&lsda));
+    const uint8_t* callSiteTableStart = lsda;
+    const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
+    const uint8_t* actionTableStart = callSiteTableEnd;
+    const uint8_t* callSitePtr = callSiteTableStart;
+    while (callSitePtr < callSiteTableEnd)
+    {
+        // There is one entry per call site.
+#ifndef __USING_SJLJ_EXCEPTIONS__
+        // The call sites are non-overlapping in [start, start+length)
+        // The call sites are ordered in increasing value of start
+        uintptr_t start = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t length = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t landingPad = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t actionEntry = readULEB128(&callSitePtr);
+        if ((start <= ipOffset) && (ipOffset < (start + length)))
+#else  // __USING_SJLJ_EXCEPTIONS__
+        // ip is 1-based index into this table
+        uintptr_t landingPad = readULEB128(&callSitePtr);
+        uintptr_t actionEntry = readULEB128(&callSitePtr);
+        if (--ip == 0)
+#endif  // __USING_SJLJ_EXCEPTIONS__
+        {
+            // Found the call site containing ip.
+#ifndef __USING_SJLJ_EXCEPTIONS__
+            if (landingPad == 0)
+            {
+                // No handler here
+                results.reason = _URC_CONTINUE_UNWIND;
+                return;
+            }
+            landingPad = (uintptr_t)lpStart + landingPad;
+#else  // __USING_SJLJ_EXCEPTIONS__
+            ++landingPad;
+#endif  // __USING_SJLJ_EXCEPTIONS__
+            if (actionEntry == 0)
+            {
+                // Found a cleanup
+                // If this is a type 1 or type 2 search, there are no handlers
+                // If this is a type 3 search, you want to install the cleanup.
+                if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME))
+                {
+                    results.ttypeIndex = 0;  // Redundant but clarifying
+                    results.landingPad = landingPad;
+                    results.reason = _URC_HANDLER_FOUND;
+                    return;
+                }
+                // No handler here
+                results.reason = _URC_CONTINUE_UNWIND;
+                return;
+            }
+            // Convert 1-based byte offset into
+            const uint8_t* action = actionTableStart + (actionEntry - 1);
+            // Scan action entries until you find a matching handler, cleanup, or the end of action list
+            while (true)
+            {
+                const uint8_t* actionRecord = action;
+                int64_t ttypeIndex = readSLEB128(&action);
+                if (ttypeIndex > 0)
+                {
+                    // Found a catch, does it actually catch?
+                    // First check for catch (...)
+                    const __shim_type_info* catchType =
+                        get_shim_type_info(static_cast<uint64_t>(ttypeIndex),
+                                           classInfo, ttypeEncoding,
+                                           native_exception, unwind_exception);
+                    if (catchType == 0)
+                    {
+                        // Found catch (...) catches everything, including foreign exceptions
+                        // If this is a type 1 search save state and return _URC_HANDLER_FOUND
+                        // If this is a type 2 search save state and return _URC_HANDLER_FOUND
+                        // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                        // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                        if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME))
+                        {
+                            // Save state and return _URC_HANDLER_FOUND
+                            results.ttypeIndex = ttypeIndex;
+                            results.actionRecord = actionRecord;
+                            results.landingPad = landingPad;
+                            results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                            results.reason = _URC_HANDLER_FOUND;
+                            return;
+                        }
+                        else if (!(actions & _UA_FORCE_UNWIND))
+                        {
+                            // It looks like the exception table has changed
+                            //    on us.  Likely stack corruption!
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                    }
+                    // Else this is a catch (T) clause and will never
+                    //    catch a foreign exception
+                    else if (native_exception)
+                    {
+                        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                        void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        const __shim_type_info* excpType =
+                            static_cast<const __shim_type_info*>(exception_header->exceptionType);
+                        if (adjustedPtr == 0 || excpType == 0)
+                        {
+                            // Something very bad happened
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                        if (catchType->can_catch(excpType, adjustedPtr))
+                        {
+                            // Found a matching handler
+                            // If this is a type 1 search save state and return _URC_HANDLER_FOUND
+                            // If this is a type 3 search and !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                            // If this is a type 3 search and _UA_FORCE_UNWIND, ignore handler and continue scan
+                            if (actions & _UA_SEARCH_PHASE)
+                            {
+                                // Save state and return _URC_HANDLER_FOUND
+                                results.ttypeIndex = ttypeIndex;
+                                results.actionRecord = actionRecord;
+                                results.landingPad = landingPad;
+                                results.adjustedPtr = adjustedPtr;
+                                results.reason = _URC_HANDLER_FOUND;
+                                return;
+                            }
+                            else if (!(actions & _UA_FORCE_UNWIND))
+                            {
+                                // It looks like the exception table has changed
+                                //    on us.  Likely stack corruption!
+                                call_terminate(native_exception, unwind_exception);
+                            }
+                        }
+                    }
+                    // Scan next action ...
+                }
+                else if (ttypeIndex < 0)
+                {
+                    // Found an exception spec.  If this is a foreign exception,
+                    //   it is always caught.
+                    if (native_exception)
+                    {
+                        // Does the exception spec catch this native exception?
+                        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                        void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        const __shim_type_info* excpType =
+                            static_cast<const __shim_type_info*>(exception_header->exceptionType);
+                        if (adjustedPtr == 0 || excpType == 0)
+                        {
+                            // Something very bad happened
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                        if (exception_spec_can_catch(ttypeIndex, classInfo,
+                                                     ttypeEncoding, excpType,
+                                                     adjustedPtr, unwind_exception))
+                        {
+                            // native exception caught by exception spec
+                            // If this is a type 1 search, save state and return _URC_HANDLER_FOUND
+                            // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                            // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                            if (actions & _UA_SEARCH_PHASE)
+                            {
+                                // Save state and return _URC_HANDLER_FOUND
+                                results.ttypeIndex = ttypeIndex;
+                                results.actionRecord = actionRecord;
+                                results.landingPad = landingPad;
+                                results.adjustedPtr = adjustedPtr;
+                                results.reason = _URC_HANDLER_FOUND;
+                                return;
+                            }
+                            else if (!(actions & _UA_FORCE_UNWIND))
+                            {
+                                // It looks like the exception table has changed
+                                //    on us.  Likely stack corruption!
+                                call_terminate(native_exception, unwind_exception);
+                            }
+                        }
+                    }
+                    else
+                    {
+                        // foreign exception caught by exception spec
+                        // If this is a type 1 search, save state and return _URC_HANDLER_FOUND
+                        // If this is a type 2 search, save state and return _URC_HANDLER_FOUND
+                        // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                        // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                        if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME))
+                        {
+                            // Save state and return _URC_HANDLER_FOUND
+                            results.ttypeIndex = ttypeIndex;
+                            results.actionRecord = actionRecord;
+                            results.landingPad = landingPad;
+                            results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                            results.reason = _URC_HANDLER_FOUND;
+                            return;
+                        }
+                        else if (!(actions & _UA_FORCE_UNWIND))
+                        {
+                            // It looks like the exception table has changed
+                            //    on us.  Likely stack corruption!
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                    }
+                    // Scan next action ...
+                }
+                else  // ttypeIndex == 0
+                {
+                    // Found a cleanup
+                    // If this is a type 1 search, ignore it and continue scan
+                    // If this is a type 2 search, ignore it and continue scan
+                    // If this is a type 3 search, save state and return _URC_HANDLER_FOUND
+                    if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME))
+                    {
+                        // Save state and return _URC_HANDLER_FOUND
+                        results.ttypeIndex = ttypeIndex;
+                        results.actionRecord = actionRecord;
+                        results.landingPad = landingPad;
+                        results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        results.reason = _URC_HANDLER_FOUND;
+                        return;
+                    }
+                }
+                const uint8_t* temp = action;
+                int64_t actionOffset = readSLEB128(&temp);
+                if (actionOffset == 0)
+                {
+                    // End of action list, no matching handler or cleanup found
+                    results.reason = _URC_CONTINUE_UNWIND;
+                    return;
+                }
+                // Go to next action
+                action += actionOffset;
+            }  // there is no break out of this loop, only return
+        }
+#ifndef __USING_SJLJ_EXCEPTIONS__
+        else if (ipOffset < start)
+        {
+            // There is no call site for this ip
+            // Something bad has happened.  We should never get here.
+            // Possible stack corruption.
+            call_terminate(native_exception, unwind_exception);
+        }
+#endif  // !__USING_SJLJ_EXCEPTIONS__
+    }  // there might be some tricky cases which break out of this loop
+
+    // It is possible that no eh table entry specify how to handle
+    // this exception. By spec, terminate it immediately.
+    call_terminate(native_exception, unwind_exception);
+}
+
+// public API
+
+/*
+The personality function branches on actions like so:
+
+_UA_SEARCH_PHASE
+
+    If _UA_CLEANUP_PHASE or _UA_HANDLER_FRAME or _UA_FORCE_UNWIND there's
+      an error from above, return _URC_FATAL_PHASE1_ERROR.
+
+    Scan for anything that could stop unwinding:
+
+       1.  A catch clause that will catch this exception
+           (will never catch foreign).
+       2.  A catch (...) (will always catch foreign).
+       3.  An exception spec that will catch this exception
+           (will always catch foreign).
+    If a handler is found
+        If not foreign
+            Save state in header
+        return _URC_HANDLER_FOUND
+    Else a handler not found
+        return _URC_CONTINUE_UNWIND
+
+_UA_CLEANUP_PHASE
+
+    If _UA_HANDLER_FRAME
+        If _UA_FORCE_UNWIND
+            How did this happen?  return _URC_FATAL_PHASE2_ERROR
+        If foreign
+            Do _UA_SEARCH_PHASE to recover state
+        else
+            Recover state from header
+        Transfer control to landing pad.  return _URC_INSTALL_CONTEXT
+
+    Else
+
+        This branch handles both normal C++ non-catching handlers (cleanups)
+          and forced unwinding.
+        Scan for anything that can not stop unwinding:
+
+            1.  A cleanup.
+
+        If a cleanup is found
+            transfer control to it. return _URC_INSTALL_CONTEXT
+        Else a cleanup is not found: return _URC_CONTINUE_UNWIND
+*/
+
+#if !defined(_LIBCXXABI_ARM_EHABI)
+#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
+static _Unwind_Reason_Code __gxx_personality_imp
+#else
+_LIBCXXABI_FUNC_VIS _Unwind_Reason_Code
+#ifdef __USING_SJLJ_EXCEPTIONS__
+__gxx_personality_sj0
+#else
+__gxx_personality_v0
+#endif
+#endif
+                    (int version, _Unwind_Action actions, uint64_t exceptionClass,
+                     _Unwind_Exception* unwind_exception, _Unwind_Context* context)
+{
+    if (version != 1 || unwind_exception == 0 || context == 0)
+        return _URC_FATAL_PHASE1_ERROR;
+
+    bool native_exception = (exceptionClass     & get_vendor_and_language) ==
+                            (kOurExceptionClass & get_vendor_and_language);
+    scan_results results;
+    if (actions & _UA_SEARCH_PHASE)
+    {
+        // Phase 1 search:  All we're looking for in phase 1 is a handler that
+        //   halts unwinding
+        scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            // Found one.  Can we cache the results somewhere to optimize phase 2?
+            if (native_exception)
+            {
+                __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                exception_header->handlerSwitchValue = static_cast<int>(results.ttypeIndex);
+                exception_header->actionRecord = results.actionRecord;
+                exception_header->languageSpecificData = results.languageSpecificData;
+                exception_header->catchTemp = reinterpret_cast<void*>(results.landingPad);
+                exception_header->adjustedPtr = results.adjustedPtr;
+            }
+            return _URC_HANDLER_FOUND;
+        }
+        // Did not find a catching-handler.  Return the results of the scan
+        //    (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE1_ERROR
+        //     if we were called improperly).
+        return results.reason;
+    }
+    if (actions & _UA_CLEANUP_PHASE)
+    {
+        // Phase 2 search:
+        //  Did we find a catching handler in phase 1?
+        if (actions & _UA_HANDLER_FRAME)
+        {
+            // Yes, phase 1 said we have a catching handler here.
+            // Did we cache the results of the scan?
+            if (native_exception)
+            {
+                // Yes, reload the results from the cache.
+                __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                results.ttypeIndex = exception_header->handlerSwitchValue;
+                results.actionRecord = exception_header->actionRecord;
+                results.languageSpecificData = exception_header->languageSpecificData;
+                results.landingPad = reinterpret_cast<uintptr_t>(exception_header->catchTemp);
+                results.adjustedPtr = exception_header->adjustedPtr;
+            }
+            else
+            {
+                // No, do the scan again to reload the results.
+                scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+                // Phase 1 told us we would find a handler.  Now in Phase 2 we
+                //   didn't find a handler.  The eh table should not be changing!
+                if (results.reason != _URC_HANDLER_FOUND)
+                    call_terminate(native_exception, unwind_exception);
+            }
+            // Jump to the handler
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+        // Either we didn't do a phase 1 search (due to forced unwinding), or
+        //   phase 1 reported no catching-handlers.
+        // Search for a (non-catching) cleanup
+        scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            // Found a non-catching handler.  Jump to it:
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+        // Did not find a cleanup.  Return the results of the scan
+        //    (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE2_ERROR
+        //     if we were called improperly).
+        return results.reason;
+    }
+    // We were called improperly: neither a phase 1 or phase 2 search
+    return _URC_FATAL_PHASE1_ERROR;
+}
+
+#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
+extern "C" _LIBCXXABI_FUNC_VIS EXCEPTION_DISPOSITION
+__gxx_personality_seh0(PEXCEPTION_RECORD ms_exc, void *this_frame,
+                       PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp)
+{
+  return _GCC_specific_handler(ms_exc, this_frame, ms_orig_context, ms_disp,
+                               __gxx_personality_imp);
+}
+#endif
+
+#else
+
+extern "C" _Unwind_Reason_Code __gnu_unwind_frame(_Unwind_Exception*,
+                                                  _Unwind_Context*);
+
+// Helper function to unwind one frame.
+// ARM EHABI 7.3 and 7.4: If the personality function returns _URC_CONTINUE_UNWIND, the
+// personality routine should update the virtual register set (VRS) according to the
+// corresponding frame unwinding instructions (ARM EHABI 9.3.)
+static _Unwind_Reason_Code continue_unwind(_Unwind_Exception* unwind_exception,
+                                           _Unwind_Context* context)
+{
+    if (__gnu_unwind_frame(unwind_exception, context) != _URC_OK)
+        return _URC_FAILURE;
+    return _URC_CONTINUE_UNWIND;
+}
+
+// ARM register names
+#if !defined(LIBCXXABI_USE_LLVM_UNWINDER)
+static const uint32_t REG_UCB = 12;  // Register to save _Unwind_Control_Block
+#endif
+static const uint32_t REG_SP = 13;
+
+static void save_results_to_barrier_cache(_Unwind_Exception* unwind_exception,
+                                          const scan_results& results)
+{
+    unwind_exception->barrier_cache.bitpattern[0] = (uint32_t)results.adjustedPtr;
+    unwind_exception->barrier_cache.bitpattern[1] = (uint32_t)results.actionRecord;
+    unwind_exception->barrier_cache.bitpattern[2] = (uint32_t)results.languageSpecificData;
+    unwind_exception->barrier_cache.bitpattern[3] = (uint32_t)results.landingPad;
+    unwind_exception->barrier_cache.bitpattern[4] = (uint32_t)results.ttypeIndex;
+}
+
+static void load_results_from_barrier_cache(scan_results& results,
+                                            const _Unwind_Exception* unwind_exception)
+{
+    results.adjustedPtr = (void*)unwind_exception->barrier_cache.bitpattern[0];
+    results.actionRecord = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[1];
+    results.languageSpecificData = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2];
+    results.landingPad = (uintptr_t)unwind_exception->barrier_cache.bitpattern[3];
+    results.ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4];
+}
+
+extern "C" _LIBCXXABI_FUNC_VIS _Unwind_Reason_Code
+__gxx_personality_v0(_Unwind_State state,
+                     _Unwind_Exception* unwind_exception,
+                     _Unwind_Context* context)
+{
+    if (unwind_exception == 0 || context == 0)
+        return _URC_FATAL_PHASE1_ERROR;
+
+    bool native_exception = __isOurExceptionClass(unwind_exception);
+
+#if !defined(LIBCXXABI_USE_LLVM_UNWINDER)
+    // Copy the address of _Unwind_Control_Block to r12 so that
+    // _Unwind_GetLanguageSpecificData() and _Unwind_GetRegionStart() can
+    // return correct address.
+    _Unwind_SetGR(context, REG_UCB, reinterpret_cast<uint32_t>(unwind_exception));
+#endif
+
+    // Check the undocumented force unwinding behavior
+    bool is_force_unwinding = state & _US_FORCE_UNWIND;
+    state &= ~_US_FORCE_UNWIND;
+
+    scan_results results;
+    switch (state) {
+    case _US_VIRTUAL_UNWIND_FRAME:
+        if (is_force_unwinding)
+            return continue_unwind(unwind_exception, context);
+
+        // Phase 1 search:  All we're looking for in phase 1 is a handler that halts unwinding
+        scan_eh_tab(results, _UA_SEARCH_PHASE, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            unwind_exception->barrier_cache.sp = _Unwind_GetGR(context, REG_SP);
+            if (native_exception)
+                save_results_to_barrier_cache(unwind_exception, results);
+            return _URC_HANDLER_FOUND;
+        }
+        // Did not find the catch handler
+        if (results.reason == _URC_CONTINUE_UNWIND)
+            return continue_unwind(unwind_exception, context);
+        return results.reason;
+
+    case _US_UNWIND_FRAME_STARTING:
+        // TODO: Support force unwinding in the phase 2 search.
+        // NOTE: In order to call the cleanup functions, _Unwind_ForcedUnwind()
+        // will call this personality function with (_US_FORCE_UNWIND |
+        // _US_UNWIND_FRAME_STARTING).
+
+        // Phase 2 search
+        if (unwind_exception->barrier_cache.sp == _Unwind_GetGR(context, REG_SP))
+        {
+            // Found a catching handler in phase 1
+            if (native_exception)
+            {
+                // Load the result from the native exception barrier cache.
+                load_results_from_barrier_cache(results, unwind_exception);
+                results.reason = _URC_HANDLER_FOUND;
+            }
+            else
+            {
+                // Search for the catching handler again for the foreign exception.
+                scan_eh_tab(results, static_cast<_Unwind_Action>(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME),
+                            native_exception, unwind_exception, context);
+                if (results.reason != _URC_HANDLER_FOUND)  // phase1 search should guarantee to find one
+                    call_terminate(native_exception, unwind_exception);
+            }
+
+            // Install the context for the catching handler
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+
+        // Either we didn't do a phase 1 search (due to forced unwinding), or
+        //  phase 1 reported no catching-handlers.
+        // Search for a (non-catching) cleanup
+        scan_eh_tab(results, _UA_CLEANUP_PHASE, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            // Found a non-catching handler
+
+            // ARM EHABI 8.4.2: Before we can jump to the cleanup handler, we have to setup some
+            // internal data structures, so that __cxa_end_cleanup() can get unwind_exception from
+            // __cxa_get_globals().
+            __cxa_begin_cleanup(unwind_exception);
+
+            // Install the context for the cleanup handler
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+
+        // Did not find any handler
+        if (results.reason == _URC_CONTINUE_UNWIND)
+            return continue_unwind(unwind_exception, context);
+        return results.reason;
+
+    case _US_UNWIND_FRAME_RESUME:
+        return continue_unwind(unwind_exception, context);
+    }
+
+    // We were called improperly: neither a phase 1 or phase 2 search
+    return _URC_FATAL_PHASE1_ERROR;
+}
+#endif
+
+
+__attribute__((noreturn))
+_LIBCXXABI_FUNC_VIS void
+__cxa_call_unexpected(void* arg)
+{
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(arg);
+    if (unwind_exception == 0)
+        call_terminate(false, unwind_exception);
+    __cxa_begin_catch(unwind_exception);
+    bool native_old_exception = __isOurExceptionClass(unwind_exception);
+    std::unexpected_handler u_handler;
+    std::terminate_handler t_handler;
+    __cxa_exception* old_exception_header = 0;
+    int64_t ttypeIndex;
+    const uint8_t* lsda;
+    if (native_old_exception)
+    {
+        old_exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+        t_handler = old_exception_header->terminateHandler;
+        u_handler = old_exception_header->unexpectedHandler;
+        // If std::__unexpected(u_handler) rethrows the same exception,
+        //   these values get overwritten by the rethrow.  So save them now:
+#if defined(_LIBCXXABI_ARM_EHABI)
+        ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4];
+        lsda = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2];
+#else
+        ttypeIndex = old_exception_header->handlerSwitchValue;
+        lsda = old_exception_header->languageSpecificData;
+#endif
+    }
+    else
+    {
+        t_handler = std::get_terminate();
+        u_handler = std::get_unexpected();
+    }
+    try
+    {
+        std::__unexpected(u_handler);
+    }
+    catch (...)
+    {
+        // If the old exception is foreign, then all we can do is terminate.
+        //   We have no way to recover the needed old exception spec.  There's
+        //   no way to pass that information here.  And the personality routine
+        //   can't call us directly and do anything but terminate() if we throw
+        //   from here.
+        if (native_old_exception)
+        {
+            // Have:
+            //   old_exception_header->languageSpecificData
+            //   old_exception_header->actionRecord
+            // Need
+            //   const uint8_t* classInfo
+            //   uint8_t ttypeEncoding
+            uint8_t lpStartEncoding = *lsda++;
+            const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding);
+            (void)lpStart;  // purposefully unused.  Just needed to increment lsda.
+            uint8_t ttypeEncoding = *lsda++;
+            if (ttypeEncoding == DW_EH_PE_omit)
+                std::__terminate(t_handler);
+            uintptr_t classInfoOffset = readULEB128(&lsda);
+            const uint8_t* classInfo = lsda + classInfoOffset;
+            // Is this new exception catchable by the exception spec at ttypeIndex?
+            // The answer is obviously yes if the new and old exceptions are the same exception
+            // If no
+            //    throw;
+            __cxa_eh_globals* globals = __cxa_get_globals_fast();
+            __cxa_exception* new_exception_header = globals->caughtExceptions;
+            if (new_exception_header == 0)
+                // This shouldn't be able to happen!
+                std::__terminate(t_handler);
+            bool native_new_exception = __isOurExceptionClass(&new_exception_header->unwindHeader);
+            void* adjustedPtr;
+            if (native_new_exception && (new_exception_header != old_exception_header))
+            {
+                const __shim_type_info* excpType =
+                    static_cast<const __shim_type_info*>(new_exception_header->exceptionType);
+                adjustedPtr =
+                    __getExceptionClass(&new_exception_header->unwindHeader) == kOurDependentExceptionClass ?
+                        ((__cxa_dependent_exception*)new_exception_header)->primaryException :
+                        new_exception_header + 1;
+                if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
+                                              excpType, adjustedPtr, unwind_exception))
+                {
+                    // We need to __cxa_end_catch, but for the old exception,
+                    //   not the new one.  This is a little tricky ...
+                    // Disguise new_exception_header as a rethrown exception, but
+                    //   don't actually rethrow it.  This means you can temporarily
+                    //   end the catch clause enclosing new_exception_header without
+                    //   __cxa_end_catch destroying new_exception_header.
+                    new_exception_header->handlerCount = -new_exception_header->handlerCount;
+                    globals->uncaughtExceptions += 1;
+                    // Call __cxa_end_catch for new_exception_header
+                    __cxa_end_catch();
+                    // Call __cxa_end_catch for old_exception_header
+                    __cxa_end_catch();
+                    // Renter this catch clause with new_exception_header
+                    __cxa_begin_catch(&new_exception_header->unwindHeader);
+                    // Rethrow new_exception_header
+                    throw;
+                }
+            }
+            // Will a std::bad_exception be catchable by the exception spec at
+            //   ttypeIndex?
+            // If no
+            //    throw std::bad_exception();
+            const __shim_type_info* excpType =
+                static_cast<const __shim_type_info*>(&typeid(std::bad_exception));
+            std::bad_exception be;
+            adjustedPtr = &be;
+            if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
+                                          excpType, adjustedPtr, unwind_exception))
+            {
+                // We need to __cxa_end_catch for both the old exception and the
+                //   new exception.  Technically we should do it in that order.
+                //   But it is expedient to do it in the opposite order:
+                // Call __cxa_end_catch for new_exception_header
+                __cxa_end_catch();
+                // Throw std::bad_exception will __cxa_end_catch for
+                //   old_exception_header
+                throw be;
+            }
+        }
+    }
+    std::__terminate(t_handler);
+}
+
+}  // extern "C"
+
+}  // __cxxabiv1
diff --git a/lib/libcxxabi/src/cxa_thread_atexit.cpp b/lib/libcxxabi/src/cxa_thread_atexit.cpp
new file mode 100644
index 0000000000..a940eaf2f9
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_thread_atexit.cpp
@@ -0,0 +1,145 @@
+//===----------------------- cxa_thread_atexit.cpp ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "abort_message.h"
+#include "cxxabi.h"
+#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+#include <stdlib.h>
+
+namespace __cxxabiv1 {
+
+  using Dtor = void(*)(void*);
+
+  extern "C"
+#ifndef HAVE___CXA_THREAD_ATEXIT_IMPL
+  // A weak symbol is used to detect this function's presence in the C library
+  // at runtime, even if libc++ is built against an older libc
+  _LIBCXXABI_WEAK
+#endif
+  int __cxa_thread_atexit_impl(Dtor, void*, void*);
+
+#ifndef HAVE___CXA_THREAD_ATEXIT_IMPL
+
+namespace {
+  // This implementation is used if the C library does not provide
+  // __cxa_thread_atexit_impl() for us.  It has a number of limitations that are
+  // difficult to impossible to address without ..._impl():
+  //
+  // - dso_symbol is ignored.  This means that a shared library may be unloaded
+  //   (via dlclose()) before its thread_local destructors have run.
+  //
+  // - thread_local destructors for the main thread are run by the destructor of
+  //   a static object.  This is later than expected; they should run before the
+  //   destructors of any objects with static storage duration.
+  //
+  // - thread_local destructors on non-main threads run on the first iteration
+  //   through the __libccpp_tls_key destructors.
+  //   std::notify_all_at_thread_exit() and similar functions must be careful to
+  //   wait until the second iteration to provide their intended ordering
+  //   guarantees.
+  //
+  // Another limitation, though one shared with ..._impl(), is that any
+  // thread_locals that are first initialized after non-thread_local global
+  // destructors begin to run will not be destroyed.  [basic.start.term] states
+  // that all thread_local destructors are sequenced before the destruction of
+  // objects with static storage duration, resulting in a contradiction if a
+  // thread_local is constructed after that point.  Thus we consider such
+  // programs ill-formed, and don't bother to run those destructors.  (If the
+  // program terminates abnormally after such a thread_local is constructed,
+  // the destructor is not expected to run and thus there is no contradiction.
+  // So construction still has to work.)
+
+  struct DtorList {
+    Dtor dtor;
+    void* obj;
+    DtorList* next;
+  };
+
+  // The linked list of thread-local destructors to run
+  __thread DtorList* dtors = nullptr;
+  // True if the destructors are currently scheduled to run on this thread
+  __thread bool dtors_alive = false;
+  // Used to trigger destructors on thread exit; value is ignored
+  std::__libcpp_tls_key dtors_key;
+
+  void run_dtors(void*) {
+    while (auto head = dtors) {
+      dtors = head->next;
+      head->dtor(head->obj);
+      ::free(head);
+    }
+
+    dtors_alive = false;
+  }
+
+  struct DtorsManager {
+    DtorsManager() {
+      // There is intentionally no matching std::__libcpp_tls_delete call, as
+      // __cxa_thread_atexit() may be called arbitrarily late (for example, from
+      // global destructors or atexit() handlers).
+      if (std::__libcpp_tls_create(&dtors_key, run_dtors) != 0) {
+        abort_message("std::__libcpp_tls_create() failed in __cxa_thread_atexit()");
+      }
+    }
+
+    ~DtorsManager() {
+      // std::__libcpp_tls_key destructors do not run on threads that call exit()
+      // (including when the main thread returns from main()), so we explicitly
+      // call the destructor here.  This runs at exit time (potentially earlier
+      // if libc++abi is dlclose()'d).  Any thread_locals initialized after this
+      // point will not be destroyed.
+      run_dtors(nullptr);
+    }
+  };
+} // namespace
+
+#endif // HAVE___CXA_THREAD_ATEXIT_IMPL
+
+extern "C" {
+
+  _LIBCXXABI_FUNC_VIS int __cxa_thread_atexit(Dtor dtor, void* obj, void* dso_symbol) throw() {
+#ifdef HAVE___CXA_THREAD_ATEXIT_IMPL
+    return __cxa_thread_atexit_impl(dtor, obj, dso_symbol);
+#else
+    if (__cxa_thread_atexit_impl) {
+      return __cxa_thread_atexit_impl(dtor, obj, dso_symbol);
+    } else {
+      // Initialize the dtors std::__libcpp_tls_key (uses __cxa_guard_*() for
+      // one-time initialization and __cxa_atexit() for destruction)
+      static DtorsManager manager;
+
+      if (!dtors_alive) {
+        if (std::__libcpp_tls_set(dtors_key, &dtors_key) != 0) {
+          return -1;
+        }
+        dtors_alive = true;
+      }
+
+      auto head = static_cast<DtorList*>(::malloc(sizeof(DtorList)));
+      if (!head) {
+        return -1;
+      }
+
+      head->dtor = dtor;
+      head->obj = obj;
+      head->next = dtors;
+      dtors = head;
+
+      return 0;
+    }
+#endif // HAVE___CXA_THREAD_ATEXIT_IMPL
+  }
+
+} // extern "C"
+} // namespace __cxxabiv1
diff --git a/lib/libcxxabi/src/cxa_unexpected.cpp b/lib/libcxxabi/src/cxa_unexpected.cpp
new file mode 100644
index 0000000000..bbfa6684ef
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_unexpected.cpp
@@ -0,0 +1,22 @@
+//===------------------------- cxa_unexpected.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <exception>
+#include "cxxabi.h"
+#include "cxa_exception.h"
+
+namespace __cxxabiv1
+{
+
+extern "C"
+{
+
+}
+
+}  // namespace __cxxabiv1
+
diff --git a/lib/libcxxabi/src/cxa_vector.cpp b/lib/libcxxabi/src/cxa_vector.cpp
new file mode 100644
index 0000000000..f20e978d36
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_vector.cpp
@@ -0,0 +1,421 @@
+//===-------------------------- cxa_vector.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Array Construction and Destruction APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi.html#array-ctor
+//
+//===----------------------------------------------------------------------===//
+
+#include "cxxabi.h"
+#include "__cxxabi_config.h"
+
+#include <exception>        // for std::terminate
+#include <new>              // for std::bad_array_new_length
+
+#include "abort_message.h"
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+namespace __cxxabiv1 {
+
+#if 0
+#pragma mark --Helper routines and classes --
+#endif
+
+namespace {
+    inline static size_t __get_element_count ( void *p ) {
+        return static_cast <size_t *> (p)[-1];
+        }
+
+    inline static void __set_element_count ( void *p, size_t element_count ) {
+        static_cast <size_t *> (p)[-1] = element_count;
+        }
+
+
+//  A pair of classes to simplify exception handling and control flow.
+//  They get passed a block of memory in the constructor, and unless the
+//  'release' method is called, they deallocate the memory in the destructor.
+//  Preferred usage is to allocate some memory, attach it to one of these objects,
+//  and then, when all the operations to set up the memory block have succeeded,
+//  call 'release'. If any of the setup operations fail, or an exception is
+//  thrown, then the block is automatically deallocated.
+//
+//  The only difference between these two classes is the signature for the
+//  deallocation function (to match new2/new3 and delete2/delete3.
+    class st_heap_block2 {
+    public:
+        typedef void (*dealloc_f)(void *);
+
+        st_heap_block2 ( dealloc_f dealloc, void *ptr )
+            : dealloc_ ( dealloc ), ptr_ ( ptr ), enabled_ ( true ) {}
+        ~st_heap_block2 () { if ( enabled_ ) dealloc_ ( ptr_ ) ; }
+        void release () { enabled_ = false; }
+
+    private:
+        dealloc_f dealloc_;
+        void *ptr_;
+        bool enabled_;
+    };
+
+    class st_heap_block3 {
+    public:
+        typedef void (*dealloc_f)(void *, size_t);
+
+        st_heap_block3 ( dealloc_f dealloc, void *ptr, size_t size )
+            : dealloc_ ( dealloc ), ptr_ ( ptr ), size_ ( size ), enabled_ ( true ) {}
+        ~st_heap_block3 () { if ( enabled_ ) dealloc_ ( ptr_, size_ ) ; }
+        void release () { enabled_ = false; }
+
+    private:
+        dealloc_f dealloc_;
+        void *ptr_;
+        size_t size_;
+        bool enabled_;
+    };
+
+    class st_cxa_cleanup {
+    public:
+        typedef void (*destruct_f)(void *);
+
+        st_cxa_cleanup ( void *ptr, size_t &idx, size_t element_size, destruct_f destructor )
+            : ptr_ ( ptr ), idx_ ( idx ), element_size_ ( element_size ),
+                destructor_ ( destructor ), enabled_ ( true ) {}
+        ~st_cxa_cleanup () {
+            if ( enabled_ )
+                __cxa_vec_cleanup ( ptr_, idx_, element_size_, destructor_ );
+            }
+
+        void release () { enabled_ = false; }
+
+    private:
+        void *ptr_;
+        size_t &idx_;
+        size_t element_size_;
+        destruct_f destructor_;
+        bool enabled_;
+    };
+
+    class st_terminate {
+    public:
+        st_terminate ( bool enabled = true ) : enabled_ ( enabled ) {}
+        ~st_terminate () { if ( enabled_ ) std::terminate (); }
+        void release () { enabled_ = false; }
+    private:
+        bool enabled_ ;
+    };
+}
+
+#if 0
+#pragma mark --Externally visible routines--
+#endif
+
+namespace {
+_LIBCXXABI_NORETURN
+void throw_bad_array_new_length() {
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+  throw std::bad_array_new_length();
+#else
+  abort_message("__cxa_vec_new failed to allocate memory");
+#endif
+}
+
+bool mul_overflow(size_t x, size_t y, size_t *res) {
+#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_mul_overflow)) \
+    || defined(_LIBCXXABI_COMPILER_GCC)
+    return __builtin_mul_overflow(x, y, res);
+#else
+    *res = x * y;
+    return x && ((*res / x) != y);
+#endif
+}
+
+bool add_overflow(size_t x, size_t y, size_t *res) {
+#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_add_overflow)) \
+    || defined(_LIBCXXABI_COMPILER_GCC)
+  return __builtin_add_overflow(x, y, res);
+#else
+  *res = x + y;
+  return *res < y;
+#endif
+}
+
+size_t calculate_allocation_size_or_throw(size_t element_count,
+                                          size_t element_size,
+                                          size_t padding_size) {
+  size_t element_heap_size;
+  if (mul_overflow(element_count, element_size, &element_heap_size))
+    throw_bad_array_new_length();
+
+  size_t allocation_size;
+  if (add_overflow(element_heap_size, padding_size, &allocation_size))
+    throw_bad_array_new_length();
+
+  return allocation_size;
+}
+
+} // namespace
+
+extern "C" {
+
+// Equivalent to
+//
+//   __cxa_vec_new2(element_count, element_size, padding_size, constructor,
+//                  destructor, &::operator new[], &::operator delete[])
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new(size_t element_count, size_t element_size, size_t padding_size,
+              void (*constructor)(void *), void (*destructor)(void *)) {
+    return __cxa_vec_new2 ( element_count, element_size, padding_size,
+        constructor, destructor, &::operator new [], &::operator delete [] );
+}
+
+
+// Given the number and size of elements for an array and the non-negative
+// size of prefix padding for a cookie, allocate space (using alloc) for
+// the array preceded by the specified padding, initialize the cookie if
+// the padding is non-zero, and call the given constructor on each element.
+// Return the address of the array proper, after the padding.
+//
+// If alloc throws an exception, rethrow the exception. If alloc returns
+// NULL, return NULL. If the constructor throws an exception, call
+// destructor for any already constructed elements, and rethrow the
+// exception. If the destructor throws an exception, call std::terminate.
+//
+// The constructor may be NULL, in which case it must not be called. If the
+// padding_size is zero, the destructor may be NULL; in that case it must
+// not be called.
+//
+// Neither alloc nor dealloc may be NULL.
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new2(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *)) {
+  const size_t heap_size = calculate_allocation_size_or_throw(
+      element_count, element_size, padding_size);
+  char* const heap_block = static_cast<char*>(alloc(heap_size));
+  char* vec_base = heap_block;
+
+  if (NULL != vec_base) {
+    st_heap_block2 heap(dealloc, heap_block);
+
+    //  put the padding before the array elements
+        if ( 0 != padding_size ) {
+            vec_base += padding_size;
+            __set_element_count ( vec_base, element_count );
+        }
+
+    //  Construct the elements
+        __cxa_vec_ctor ( vec_base, element_count, element_size, constructor, destructor );
+        heap.release ();    // We're good!
+    }
+
+    return vec_base;
+}
+
+
+// Same as __cxa_vec_new2 except that the deallocation function takes both
+// the object address and its size.
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new3(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *, size_t)) {
+  const size_t heap_size = calculate_allocation_size_or_throw(
+      element_count, element_size, padding_size);
+  char* const heap_block = static_cast<char*>(alloc(heap_size));
+  char* vec_base = heap_block;
+
+  if (NULL != vec_base) {
+    st_heap_block3 heap(dealloc, heap_block, heap_size);
+
+    //  put the padding before the array elements
+        if ( 0 != padding_size ) {
+            vec_base += padding_size;
+            __set_element_count ( vec_base, element_count );
+        }
+
+    //  Construct the elements
+        __cxa_vec_ctor ( vec_base, element_count, element_size, constructor, destructor );
+        heap.release ();    // We're good!
+    }
+
+    return vec_base;
+}
+
+
+// Given the (data) addresses of a destination and a source array, an
+// element count and an element size, call the given copy constructor to
+// copy each element from the source array to the destination array. The
+// copy constructor's arguments are the destination address and source
+// address, respectively. If an exception occurs, call the given destructor
+// (if non-NULL) on each copied element and rethrow. If the destructor
+// throws an exception, call terminate(). The constructor and or destructor
+// pointers may be NULL. If either is NULL, no action is taken when it
+// would have been called.
+
+_LIBCXXABI_FUNC_VIS void __cxa_vec_cctor(void *dest_array, void *src_array,
+                                         size_t element_count,
+                                         size_t element_size,
+                                         void (*constructor)(void *, void *),
+                                         void (*destructor)(void *)) {
+    if ( NULL != constructor ) {
+        size_t idx = 0;
+        char *src_ptr  = static_cast<char *>(src_array);
+        char *dest_ptr = static_cast<char *>(dest_array);
+        st_cxa_cleanup cleanup ( dest_array, idx, element_size, destructor );
+
+        for ( idx = 0; idx < element_count;
+                    ++idx, src_ptr += element_size, dest_ptr += element_size )
+            constructor ( dest_ptr, src_ptr );
+        cleanup.release ();     // We're good!
+    }
+}
+
+
+// Given the (data) address of an array, not including any cookie padding,
+// and the number and size of its elements, call the given constructor on
+// each element. If the constructor throws an exception, call the given
+// destructor for any already-constructed elements, and rethrow the
+// exception. If the destructor throws an exception, call terminate(). The
+// constructor and/or destructor pointers may be NULL. If either is NULL,
+// no action is taken when it would have been called.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_ctor(void *array_address, size_t element_count, size_t element_size,
+               void (*constructor)(void *), void (*destructor)(void *)) {
+    if ( NULL != constructor ) {
+        size_t idx;
+        char *ptr = static_cast <char *> ( array_address );
+        st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
+
+    //  Construct the elements
+        for ( idx = 0; idx < element_count; ++idx, ptr += element_size )
+            constructor ( ptr );
+        cleanup.release ();     // We're good!
+    }
+}
+
+// Given the (data) address of an array, the number of elements, and the
+// size of its elements, call the given destructor on each element. If the
+// destructor throws an exception, rethrow after destroying the remaining
+// elements if possible. If the destructor throws a second exception, call
+// terminate(). The destructor pointer may be NULL, in which case this
+// routine does nothing.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_dtor(void *array_address,
+                                        size_t element_count,
+                                        size_t element_size,
+                                        void (*destructor)(void *)) {
+    if ( NULL != destructor ) {
+        char *ptr = static_cast <char *> (array_address);
+        size_t idx = element_count;
+        st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
+        {
+            st_terminate exception_guard (__cxa_uncaught_exception ());
+            ptr +=  element_count * element_size;   // one past the last element
+
+            while ( idx-- > 0 ) {
+                ptr -= element_size;
+                destructor ( ptr );
+            }
+            exception_guard.release (); //  We're good !
+        }
+        cleanup.release ();     // We're still good!
+    }
+}
+
+// Given the (data) address of an array, the number of elements, and the
+// size of its elements, call the given destructor on each element. If the
+// destructor throws an exception, call terminate(). The destructor pointer
+// may be NULL, in which case this routine does nothing.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_cleanup(void *array_address,
+                                           size_t element_count,
+                                           size_t element_size,
+                                           void (*destructor)(void *)) {
+    if ( NULL != destructor ) {
+        char *ptr = static_cast <char *> (array_address);
+        size_t idx = element_count;
+        st_terminate exception_guard;
+
+        ptr += element_count * element_size;    // one past the last element
+        while ( idx-- > 0 ) {
+            ptr -= element_size;
+            destructor ( ptr );
+            }
+        exception_guard.release ();     // We're done!
+    }
+}
+
+
+// If the array_address is NULL, return immediately. Otherwise, given the
+// (data) address of an array, the non-negative size of prefix padding for
+// the cookie, and the size of its elements, call the given destructor on
+// each element, using the cookie to determine the number of elements, and
+// then delete the space by calling ::operator delete[](void *). If the
+// destructor throws an exception, rethrow after (a) destroying the
+// remaining elements, and (b) deallocating the storage. If the destructor
+// throws a second exception, call terminate(). If padding_size is 0, the
+// destructor pointer must be NULL. If the destructor pointer is NULL, no
+// destructor call is to be made.
+//
+// The intent of this function is to permit an implementation to call this
+// function when confronted with an expression of the form delete[] p in
+// the source code, provided that the default deallocation function can be
+// used. Therefore, the semantics of this function are consistent with
+// those required by the standard. The requirement that the deallocation
+// function be called even if the destructor throws an exception derives
+// from the resolution to DR 353 to the C++ standard, which was adopted in
+// April, 2003.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_delete(void *array_address,
+                                          size_t element_size,
+                                          size_t padding_size,
+                                          void (*destructor)(void *)) {
+    __cxa_vec_delete2 ( array_address, element_size, padding_size,
+               destructor, &::operator delete [] );
+}
+
+// Same as __cxa_vec_delete, except that the given function is used for
+// deallocation instead of the default delete function. If dealloc throws
+// an exception, the result is undefined. The dealloc pointer may not be
+// NULL.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete2(void *array_address, size_t element_size, size_t padding_size,
+                  void (*destructor)(void *), void (*dealloc)(void *)) {
+    if ( NULL != array_address ) {
+        char *vec_base   = static_cast <char *> (array_address);
+        char *heap_block = vec_base - padding_size;
+        st_heap_block2 heap ( dealloc, heap_block );
+
+        if ( 0 != padding_size && NULL != destructor ) // call the destructors
+            __cxa_vec_dtor ( array_address, __get_element_count ( vec_base ),
+                                    element_size, destructor );
+    }
+}
+
+
+// Same as __cxa_vec_delete, except that the given function is used for
+// deallocation instead of the default delete function. The deallocation
+// function takes both the object address and its size. If dealloc throws
+// an exception, the result is undefined. The dealloc pointer may not be
+// NULL.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete3(void *array_address, size_t element_size, size_t padding_size,
+                  void (*destructor)(void *), void (*dealloc)(void *, size_t)) {
+    if ( NULL != array_address ) {
+        char *vec_base   = static_cast <char *> (array_address);
+        char *heap_block = vec_base - padding_size;
+        const size_t element_count = padding_size ? __get_element_count ( vec_base ) : 0;
+        const size_t heap_block_size = element_size * element_count + padding_size;
+        st_heap_block3 heap ( dealloc, heap_block, heap_block_size );
+
+        if ( 0 != padding_size && NULL != destructor ) // call the destructors
+            __cxa_vec_dtor ( array_address, element_count, element_size, destructor );
+    }
+}
+
+
+}  // extern "C"
+
+}  // abi
diff --git a/lib/libcxxabi/src/cxa_virtual.cpp b/lib/libcxxabi/src/cxa_virtual.cpp
new file mode 100644
index 0000000000..9214c1f3e2
--- /dev/null
+++ b/lib/libcxxabi/src/cxa_virtual.cpp
@@ -0,0 +1,24 @@
+//===-------------------------- cxa_virtual.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "cxxabi.h"
+#include "abort_message.h"
+
+namespace __cxxabiv1 {
+extern "C" {
+_LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN
+void __cxa_pure_virtual(void) {
+  abort_message("Pure virtual function called!");
+}
+
+_LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN
+void __cxa_deleted_virtual(void) {
+  abort_message("Deleted virtual function called!");
+}
+} // extern "C"
+} // abi
diff --git a/lib/libcxxabi/src/demangle/.clang-format b/lib/libcxxabi/src/demangle/.clang-format
new file mode 100644
index 0000000000..5bead5f39d
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/.clang-format
@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+
diff --git a/lib/libcxxabi/src/demangle/DemangleConfig.h b/lib/libcxxabi/src/demangle/DemangleConfig.h
new file mode 100644
index 0000000000..9d818535b0
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/DemangleConfig.h
@@ -0,0 +1,97 @@
+//===--- DemangleConfig.h --------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// This file is contains a subset of macros copied from
+// llvm/include/llvm/Demangle/DemangleConfig.h
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBCXXABI_DEMANGLE_DEMANGLE_CONFIG_H
+#define LIBCXXABI_DEMANGLE_DEMANGLE_CONFIG_H
+
+#include <ciso646>
+
+#ifdef _MSC_VER
+// snprintf is implemented in VS 2015
+#if _MSC_VER < 1900
+#define snprintf _snprintf_s
+#endif
+#endif
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#ifndef __has_cpp_attribute
+#define __has_cpp_attribute(x) 0
+#endif
+
+#ifndef __has_attribute
+#define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef DEMANGLE_GNUC_PREREQ
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch)                           \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >=          \
+   ((maj) << 20) + ((min) << 10) + (patch))
+#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch)                           \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
+#else
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch) 0
+#endif
+#endif
+
+#if __has_attribute(used) || DEMANGLE_GNUC_PREREQ(3, 1, 0)
+#define DEMANGLE_ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define DEMANGLE_ATTRIBUTE_USED
+#endif
+
+#if __has_builtin(__builtin_unreachable) || DEMANGLE_GNUC_PREREQ(4, 5, 0)
+#define DEMANGLE_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+#define DEMANGLE_UNREACHABLE __assume(false)
+#else
+#define DEMANGLE_UNREACHABLE
+#endif
+
+#if __has_attribute(noinline) || DEMANGLE_GNUC_PREREQ(3, 4, 0)
+#define DEMANGLE_ATTRIBUTE_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+#define DEMANGLE_ATTRIBUTE_NOINLINE __declspec(noinline)
+#else
+#define DEMANGLE_ATTRIBUTE_NOINLINE
+#endif
+
+#if !defined(NDEBUG)
+#define DEMANGLE_DUMP_METHOD DEMANGLE_ATTRIBUTE_NOINLINE DEMANGLE_ATTRIBUTE_USED
+#else
+#define DEMANGLE_DUMP_METHOD DEMANGLE_ATTRIBUTE_NOINLINE
+#endif
+
+#if __cplusplus > 201402L && __has_cpp_attribute(fallthrough)
+#define DEMANGLE_FALLTHROUGH [[fallthrough]]
+#elif __has_cpp_attribute(gnu::fallthrough)
+#define DEMANGLE_FALLTHROUGH [[gnu::fallthrough]]
+#elif !__cplusplus
+// Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious
+// error when __has_cpp_attribute is given a scoped attribute in C mode.
+#define DEMANGLE_FALLTHROUGH
+#elif __has_cpp_attribute(clang::fallthrough)
+#define DEMANGLE_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define DEMANGLE_FALLTHROUGH
+#endif
+
+#define DEMANGLE_NAMESPACE_BEGIN namespace { namespace itanium_demangle {
+#define DEMANGLE_NAMESPACE_END } }
+
+#endif // LIBCXXABI_DEMANGLE_DEMANGLE_CONFIG_H
diff --git a/lib/libcxxabi/src/demangle/ItaniumDemangle.h b/lib/libcxxabi/src/demangle/ItaniumDemangle.h
new file mode 100644
index 0000000000..376e0efea4
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -0,0 +1,5545 @@
+//===------------------------- ItaniumDemangle.h ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Generic itanium demangler library. This file has two byte-per-byte identical
+// copies in the source tree, one in libcxxabi, and the other in llvm.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_ITANIUMDEMANGLE_H
+#define DEMANGLE_ITANIUMDEMANGLE_H
+
+// FIXME: (possibly) incomplete list of features that clang mangles that this
+// file does not yet support:
+//   - C++ modules TS
+
+#include "DemangleConfig.h"
+#include "StringView.h"
+#include "Utility.h"
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <numeric>
+#include <utility>
+
+#define FOR_EACH_NODE_KIND(X) \
+    X(NodeArrayNode) \
+    X(DotSuffix) \
+    X(VendorExtQualType) \
+    X(QualType) \
+    X(ConversionOperatorType) \
+    X(PostfixQualifiedType) \
+    X(ElaboratedTypeSpefType) \
+    X(NameType) \
+    X(AbiTagAttr) \
+    X(EnableIfAttr) \
+    X(ObjCProtoName) \
+    X(PointerType) \
+    X(ReferenceType) \
+    X(PointerToMemberType) \
+    X(ArrayType) \
+    X(FunctionType) \
+    X(NoexceptSpec) \
+    X(DynamicExceptionSpec) \
+    X(FunctionEncoding) \
+    X(LiteralOperator) \
+    X(SpecialName) \
+    X(CtorVtableSpecialName) \
+    X(QualifiedName) \
+    X(NestedName) \
+    X(LocalName) \
+    X(VectorType) \
+    X(PixelVectorType) \
+    X(SyntheticTemplateParamName) \
+    X(TypeTemplateParamDecl) \
+    X(NonTypeTemplateParamDecl) \
+    X(TemplateTemplateParamDecl) \
+    X(TemplateParamPackDecl) \
+    X(ParameterPack) \
+    X(TemplateArgumentPack) \
+    X(ParameterPackExpansion) \
+    X(TemplateArgs) \
+    X(ForwardTemplateReference) \
+    X(NameWithTemplateArgs) \
+    X(GlobalQualifiedName) \
+    X(StdQualifiedName) \
+    X(ExpandedSpecialSubstitution) \
+    X(SpecialSubstitution) \
+    X(CtorDtorName) \
+    X(DtorName) \
+    X(UnnamedTypeName) \
+    X(ClosureTypeName) \
+    X(StructuredBindingName) \
+    X(BinaryExpr) \
+    X(ArraySubscriptExpr) \
+    X(PostfixExpr) \
+    X(ConditionalExpr) \
+    X(MemberExpr) \
+    X(EnclosingExpr) \
+    X(CastExpr) \
+    X(SizeofParamPackExpr) \
+    X(CallExpr) \
+    X(NewExpr) \
+    X(DeleteExpr) \
+    X(PrefixExpr) \
+    X(FunctionParam) \
+    X(ConversionExpr) \
+    X(InitListExpr) \
+    X(FoldExpr) \
+    X(ThrowExpr) \
+    X(UUIDOfExpr) \
+    X(BoolExpr) \
+    X(StringLiteral) \
+    X(LambdaExpr) \
+    X(IntegerCastExpr) \
+    X(IntegerLiteral) \
+    X(FloatLiteral) \
+    X(DoubleLiteral) \
+    X(LongDoubleLiteral) \
+    X(BracedExpr) \
+    X(BracedRangeExpr)
+
+DEMANGLE_NAMESPACE_BEGIN
+
+// Base class of all AST nodes. The AST is built by the parser, then is
+// traversed by the printLeft/Right functions to produce a demangled string.
+class Node {
+public:
+  enum Kind : unsigned char {
+#define ENUMERATOR(NodeKind) K ## NodeKind,
+    FOR_EACH_NODE_KIND(ENUMERATOR)
+#undef ENUMERATOR
+  };
+
+  /// Three-way bool to track a cached value. Unknown is possible if this node
+  /// has an unexpanded parameter pack below it that may affect this cache.
+  enum class Cache : unsigned char { Yes, No, Unknown, };
+
+private:
+  Kind K;
+
+  // FIXME: Make these protected.
+public:
+  /// Tracks if this node has a component on its right side, in which case we
+  /// need to call printRight.
+  Cache RHSComponentCache;
+
+  /// Track if this node is a (possibly qualified) array type. This can affect
+  /// how we format the output string.
+  Cache ArrayCache;
+
+  /// Track if this node is a (possibly qualified) function type. This can
+  /// affect how we format the output string.
+  Cache FunctionCache;
+
+public:
+  Node(Kind K_, Cache RHSComponentCache_ = Cache::No,
+       Cache ArrayCache_ = Cache::No, Cache FunctionCache_ = Cache::No)
+      : K(K_), RHSComponentCache(RHSComponentCache_), ArrayCache(ArrayCache_),
+        FunctionCache(FunctionCache_) {}
+
+  /// Visit the most-derived object corresponding to this object.
+  template<typename Fn> void visit(Fn F) const;
+
+  // The following function is provided by all derived classes:
+  //
+  // Call F with arguments that, when passed to the constructor of this node,
+  // would construct an equivalent node.
+  //template<typename Fn> void match(Fn F) const;
+
+  bool hasRHSComponent(OutputStream &S) const {
+    if (RHSComponentCache != Cache::Unknown)
+      return RHSComponentCache == Cache::Yes;
+    return hasRHSComponentSlow(S);
+  }
+
+  bool hasArray(OutputStream &S) const {
+    if (ArrayCache != Cache::Unknown)
+      return ArrayCache == Cache::Yes;
+    return hasArraySlow(S);
+  }
+
+  bool hasFunction(OutputStream &S) const {
+    if (FunctionCache != Cache::Unknown)
+      return FunctionCache == Cache::Yes;
+    return hasFunctionSlow(S);
+  }
+
+  Kind getKind() const { return K; }
+
+  virtual bool hasRHSComponentSlow(OutputStream &) const { return false; }
+  virtual bool hasArraySlow(OutputStream &) const { return false; }
+  virtual bool hasFunctionSlow(OutputStream &) const { return false; }
+
+  // Dig through "glue" nodes like ParameterPack and ForwardTemplateReference to
+  // get at a node that actually represents some concrete syntax.
+  virtual const Node *getSyntaxNode(OutputStream &) const {
+    return this;
+  }
+
+  void print(OutputStream &S) const {
+    printLeft(S);
+    if (RHSComponentCache != Cache::No)
+      printRight(S);
+  }
+
+  // Print the "left" side of this Node into OutputStream.
+  virtual void printLeft(OutputStream &) const = 0;
+
+  // Print the "right". This distinction is necessary to represent C++ types
+  // that appear on the RHS of their subtype, such as arrays or functions.
+  // Since most types don't have such a component, provide a default
+  // implementation.
+  virtual void printRight(OutputStream &) const {}
+
+  virtual StringView getBaseName() const { return StringView(); }
+
+  // Silence compiler warnings, this dtor will never be called.
+  virtual ~Node() = default;
+
+#ifndef NDEBUG
+  DEMANGLE_DUMP_METHOD void dump() const;
+#endif
+};
+
+class NodeArray {
+  Node **Elements;
+  size_t NumElements;
+
+public:
+  NodeArray() : Elements(nullptr), NumElements(0) {}
+  NodeArray(Node **Elements_, size_t NumElements_)
+      : Elements(Elements_), NumElements(NumElements_) {}
+
+  bool empty() const { return NumElements == 0; }
+  size_t size() const { return NumElements; }
+
+  Node **begin() const { return Elements; }
+  Node **end() const { return Elements + NumElements; }
+
+  Node *operator[](size_t Idx) const { return Elements[Idx]; }
+
+  void printWithComma(OutputStream &S) const {
+    bool FirstElement = true;
+    for (size_t Idx = 0; Idx != NumElements; ++Idx) {
+      size_t BeforeComma = S.getCurrentPosition();
+      if (!FirstElement)
+        S += ", ";
+      size_t AfterComma = S.getCurrentPosition();
+      Elements[Idx]->print(S);
+
+      // Elements[Idx] is an empty parameter pack expansion, we should erase the
+      // comma we just printed.
+      if (AfterComma == S.getCurrentPosition()) {
+        S.setCurrentPosition(BeforeComma);
+        continue;
+      }
+
+      FirstElement = false;
+    }
+  }
+};
+
+struct NodeArrayNode : Node {
+  NodeArray Array;
+  NodeArrayNode(NodeArray Array_) : Node(KNodeArrayNode), Array(Array_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Array); }
+
+  void printLeft(OutputStream &S) const override {
+    Array.printWithComma(S);
+  }
+};
+
+class DotSuffix final : public Node {
+  const Node *Prefix;
+  const StringView Suffix;
+
+public:
+  DotSuffix(const Node *Prefix_, StringView Suffix_)
+      : Node(KDotSuffix), Prefix(Prefix_), Suffix(Suffix_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Prefix, Suffix); }
+
+  void printLeft(OutputStream &s) const override {
+    Prefix->print(s);
+    s += " (";
+    s += Suffix;
+    s += ")";
+  }
+};
+
+class VendorExtQualType final : public Node {
+  const Node *Ty;
+  StringView Ext;
+
+public:
+  VendorExtQualType(const Node *Ty_, StringView Ext_)
+      : Node(KVendorExtQualType), Ty(Ty_), Ext(Ext_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Ext); }
+
+  void printLeft(OutputStream &S) const override {
+    Ty->print(S);
+    S += " ";
+    S += Ext;
+  }
+};
+
+enum FunctionRefQual : unsigned char {
+  FrefQualNone,
+  FrefQualLValue,
+  FrefQualRValue,
+};
+
+enum Qualifiers {
+  QualNone = 0,
+  QualConst = 0x1,
+  QualVolatile = 0x2,
+  QualRestrict = 0x4,
+};
+
+inline Qualifiers operator|=(Qualifiers &Q1, Qualifiers Q2) {
+  return Q1 = static_cast<Qualifiers>(Q1 | Q2);
+}
+
+class QualType final : public Node {
+protected:
+  const Qualifiers Quals;
+  const Node *Child;
+
+  void printQuals(OutputStream &S) const {
+    if (Quals & QualConst)
+      S += " const";
+    if (Quals & QualVolatile)
+      S += " volatile";
+    if (Quals & QualRestrict)
+      S += " restrict";
+  }
+
+public:
+  QualType(const Node *Child_, Qualifiers Quals_)
+      : Node(KQualType, Child_->RHSComponentCache,
+             Child_->ArrayCache, Child_->FunctionCache),
+        Quals(Quals_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child, Quals); }
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    return Child->hasRHSComponent(S);
+  }
+  bool hasArraySlow(OutputStream &S) const override {
+    return Child->hasArray(S);
+  }
+  bool hasFunctionSlow(OutputStream &S) const override {
+    return Child->hasFunction(S);
+  }
+
+  void printLeft(OutputStream &S) const override {
+    Child->printLeft(S);
+    printQuals(S);
+  }
+
+  void printRight(OutputStream &S) const override { Child->printRight(S); }
+};
+
+class ConversionOperatorType final : public Node {
+  const Node *Ty;
+
+public:
+  ConversionOperatorType(const Node *Ty_)
+      : Node(KConversionOperatorType), Ty(Ty_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "operator ";
+    Ty->print(S);
+  }
+};
+
+class PostfixQualifiedType final : public Node {
+  const Node *Ty;
+  const StringView Postfix;
+
+public:
+  PostfixQualifiedType(Node *Ty_, StringView Postfix_)
+      : Node(KPostfixQualifiedType), Ty(Ty_), Postfix(Postfix_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Postfix); }
+
+  void printLeft(OutputStream &s) const override {
+    Ty->printLeft(s);
+    s += Postfix;
+  }
+};
+
+class NameType final : public Node {
+  const StringView Name;
+
+public:
+  NameType(StringView Name_) : Node(KNameType), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name); }
+
+  StringView getName() const { return Name; }
+  StringView getBaseName() const override { return Name; }
+
+  void printLeft(OutputStream &s) const override { s += Name; }
+};
+
+class ElaboratedTypeSpefType : public Node {
+  StringView Kind;
+  Node *Child;
+public:
+  ElaboratedTypeSpefType(StringView Kind_, Node *Child_)
+      : Node(KElaboratedTypeSpefType), Kind(Kind_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Kind, Child); }
+
+  void printLeft(OutputStream &S) const override {
+    S += Kind;
+    S += ' ';
+    Child->print(S);
+  }
+};
+
+struct AbiTagAttr : Node {
+  Node *Base;
+  StringView Tag;
+
+  AbiTagAttr(Node* Base_, StringView Tag_)
+      : Node(KAbiTagAttr, Base_->RHSComponentCache,
+             Base_->ArrayCache, Base_->FunctionCache),
+        Base(Base_), Tag(Tag_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base, Tag); }
+
+  void printLeft(OutputStream &S) const override {
+    Base->printLeft(S);
+    S += "[abi:";
+    S += Tag;
+    S += "]";
+  }
+};
+
+class EnableIfAttr : public Node {
+  NodeArray Conditions;
+public:
+  EnableIfAttr(NodeArray Conditions_)
+      : Node(KEnableIfAttr), Conditions(Conditions_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Conditions); }
+
+  void printLeft(OutputStream &S) const override {
+    S += " [enable_if:";
+    Conditions.printWithComma(S);
+    S += ']';
+  }
+};
+
+class ObjCProtoName : public Node {
+  const Node *Ty;
+  StringView Protocol;
+
+  friend class PointerType;
+
+public:
+  ObjCProtoName(const Node *Ty_, StringView Protocol_)
+      : Node(KObjCProtoName), Ty(Ty_), Protocol(Protocol_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Protocol); }
+
+  bool isObjCObject() const {
+    return Ty->getKind() == KNameType &&
+           static_cast<const NameType *>(Ty)->getName() == "objc_object";
+  }
+
+  void printLeft(OutputStream &S) const override {
+    Ty->print(S);
+    S += "<";
+    S += Protocol;
+    S += ">";
+  }
+};
+
+class PointerType final : public Node {
+  const Node *Pointee;
+
+public:
+  PointerType(const Node *Pointee_)
+      : Node(KPointerType, Pointee_->RHSComponentCache),
+        Pointee(Pointee_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Pointee); }
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    return Pointee->hasRHSComponent(S);
+  }
+
+  void printLeft(OutputStream &s) const override {
+    // We rewrite objc_object<SomeProtocol>* into id<SomeProtocol>.
+    if (Pointee->getKind() != KObjCProtoName ||
+        !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
+      Pointee->printLeft(s);
+      if (Pointee->hasArray(s))
+        s += " ";
+      if (Pointee->hasArray(s) || Pointee->hasFunction(s))
+        s += "(";
+      s += "*";
+    } else {
+      const auto *objcProto = static_cast<const ObjCProtoName *>(Pointee);
+      s += "id<";
+      s += objcProto->Protocol;
+      s += ">";
+    }
+  }
+
+  void printRight(OutputStream &s) const override {
+    if (Pointee->getKind() != KObjCProtoName ||
+        !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
+      if (Pointee->hasArray(s) || Pointee->hasFunction(s))
+        s += ")";
+      Pointee->printRight(s);
+    }
+  }
+};
+
+enum class ReferenceKind {
+  LValue,
+  RValue,
+};
+
+// Represents either a LValue or an RValue reference type.
+class ReferenceType : public Node {
+  const Node *Pointee;
+  ReferenceKind RK;
+
+  mutable bool Printing = false;
+
+  // Dig through any refs to refs, collapsing the ReferenceTypes as we go. The
+  // rule here is rvalue ref to rvalue ref collapses to a rvalue ref, and any
+  // other combination collapses to a lvalue ref.
+  std::pair<ReferenceKind, const Node *> collapse(OutputStream &S) const {
+    auto SoFar = std::make_pair(RK, Pointee);
+    for (;;) {
+      const Node *SN = SoFar.second->getSyntaxNode(S);
+      if (SN->getKind() != KReferenceType)
+        break;
+      auto *RT = static_cast<const ReferenceType *>(SN);
+      SoFar.second = RT->Pointee;
+      SoFar.first = std::min(SoFar.first, RT->RK);
+    }
+    return SoFar;
+  }
+
+public:
+  ReferenceType(const Node *Pointee_, ReferenceKind RK_)
+      : Node(KReferenceType, Pointee_->RHSComponentCache),
+        Pointee(Pointee_), RK(RK_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Pointee, RK); }
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    return Pointee->hasRHSComponent(S);
+  }
+
+  void printLeft(OutputStream &s) const override {
+    if (Printing)
+      return;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(s);
+    Collapsed.second->printLeft(s);
+    if (Collapsed.second->hasArray(s))
+      s += " ";
+    if (Collapsed.second->hasArray(s) || Collapsed.second->hasFunction(s))
+      s += "(";
+
+    s += (Collapsed.first == ReferenceKind::LValue ? "&" : "&&");
+  }
+  void printRight(OutputStream &s) const override {
+    if (Printing)
+      return;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(s);
+    if (Collapsed.second->hasArray(s) || Collapsed.second->hasFunction(s))
+      s += ")";
+    Collapsed.second->printRight(s);
+  }
+};
+
+class PointerToMemberType final : public Node {
+  const Node *ClassType;
+  const Node *MemberType;
+
+public:
+  PointerToMemberType(const Node *ClassType_, const Node *MemberType_)
+      : Node(KPointerToMemberType, MemberType_->RHSComponentCache),
+        ClassType(ClassType_), MemberType(MemberType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(ClassType, MemberType); }
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    return MemberType->hasRHSComponent(S);
+  }
+
+  void printLeft(OutputStream &s) const override {
+    MemberType->printLeft(s);
+    if (MemberType->hasArray(s) || MemberType->hasFunction(s))
+      s += "(";
+    else
+      s += " ";
+    ClassType->print(s);
+    s += "::*";
+  }
+
+  void printRight(OutputStream &s) const override {
+    if (MemberType->hasArray(s) || MemberType->hasFunction(s))
+      s += ")";
+    MemberType->printRight(s);
+  }
+};
+
+class ArrayType final : public Node {
+  const Node *Base;
+  Node *Dimension;
+
+public:
+  ArrayType(const Node *Base_, Node *Dimension_)
+      : Node(KArrayType,
+             /*RHSComponentCache=*/Cache::Yes,
+             /*ArrayCache=*/Cache::Yes),
+        Base(Base_), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base, Dimension); }
+
+  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
+  bool hasArraySlow(OutputStream &) const override { return true; }
+
+  void printLeft(OutputStream &S) const override { Base->printLeft(S); }
+
+  void printRight(OutputStream &S) const override {
+    if (S.back() != ']')
+      S += " ";
+    S += "[";
+    if (Dimension)
+      Dimension->print(S);
+    S += "]";
+    Base->printRight(S);
+  }
+};
+
+class FunctionType final : public Node {
+  const Node *Ret;
+  NodeArray Params;
+  Qualifiers CVQuals;
+  FunctionRefQual RefQual;
+  const Node *ExceptionSpec;
+
+public:
+  FunctionType(const Node *Ret_, NodeArray Params_, Qualifiers CVQuals_,
+               FunctionRefQual RefQual_, const Node *ExceptionSpec_)
+      : Node(KFunctionType,
+             /*RHSComponentCache=*/Cache::Yes, /*ArrayCache=*/Cache::No,
+             /*FunctionCache=*/Cache::Yes),
+        Ret(Ret_), Params(Params_), CVQuals(CVQuals_), RefQual(RefQual_),
+        ExceptionSpec(ExceptionSpec_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(Ret, Params, CVQuals, RefQual, ExceptionSpec);
+  }
+
+  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
+  bool hasFunctionSlow(OutputStream &) const override { return true; }
+
+  // Handle C++'s ... quirky decl grammar by using the left & right
+  // distinction. Consider:
+  //   int (*f(float))(char) {}
+  // f is a function that takes a float and returns a pointer to a function
+  // that takes a char and returns an int. If we're trying to print f, start
+  // by printing out the return types's left, then print our parameters, then
+  // finally print right of the return type.
+  void printLeft(OutputStream &S) const override {
+    Ret->printLeft(S);
+    S += " ";
+  }
+
+  void printRight(OutputStream &S) const override {
+    S += "(";
+    Params.printWithComma(S);
+    S += ")";
+    Ret->printRight(S);
+
+    if (CVQuals & QualConst)
+      S += " const";
+    if (CVQuals & QualVolatile)
+      S += " volatile";
+    if (CVQuals & QualRestrict)
+      S += " restrict";
+
+    if (RefQual == FrefQualLValue)
+      S += " &";
+    else if (RefQual == FrefQualRValue)
+      S += " &&";
+
+    if (ExceptionSpec != nullptr) {
+      S += ' ';
+      ExceptionSpec->print(S);
+    }
+  }
+};
+
+class NoexceptSpec : public Node {
+  const Node *E;
+public:
+  NoexceptSpec(const Node *E_) : Node(KNoexceptSpec), E(E_) {}
+
+  template<typename Fn> void match(Fn F) const { F(E); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "noexcept(";
+    E->print(S);
+    S += ")";
+  }
+};
+
+class DynamicExceptionSpec : public Node {
+  NodeArray Types;
+public:
+  DynamicExceptionSpec(NodeArray Types_)
+      : Node(KDynamicExceptionSpec), Types(Types_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Types); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "throw(";
+    Types.printWithComma(S);
+    S += ')';
+  }
+};
+
+class FunctionEncoding final : public Node {
+  const Node *Ret;
+  const Node *Name;
+  NodeArray Params;
+  const Node *Attrs;
+  Qualifiers CVQuals;
+  FunctionRefQual RefQual;
+
+public:
+  FunctionEncoding(const Node *Ret_, const Node *Name_, NodeArray Params_,
+                   const Node *Attrs_, Qualifiers CVQuals_,
+                   FunctionRefQual RefQual_)
+      : Node(KFunctionEncoding,
+             /*RHSComponentCache=*/Cache::Yes, /*ArrayCache=*/Cache::No,
+             /*FunctionCache=*/Cache::Yes),
+        Ret(Ret_), Name(Name_), Params(Params_), Attrs(Attrs_),
+        CVQuals(CVQuals_), RefQual(RefQual_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(Ret, Name, Params, Attrs, CVQuals, RefQual);
+  }
+
+  Qualifiers getCVQuals() const { return CVQuals; }
+  FunctionRefQual getRefQual() const { return RefQual; }
+  NodeArray getParams() const { return Params; }
+  const Node *getReturnType() const { return Ret; }
+
+  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
+  bool hasFunctionSlow(OutputStream &) const override { return true; }
+
+  const Node *getName() const { return Name; }
+
+  void printLeft(OutputStream &S) const override {
+    if (Ret) {
+      Ret->printLeft(S);
+      if (!Ret->hasRHSComponent(S))
+        S += " ";
+    }
+    Name->print(S);
+  }
+
+  void printRight(OutputStream &S) const override {
+    S += "(";
+    Params.printWithComma(S);
+    S += ")";
+    if (Ret)
+      Ret->printRight(S);
+
+    if (CVQuals & QualConst)
+      S += " const";
+    if (CVQuals & QualVolatile)
+      S += " volatile";
+    if (CVQuals & QualRestrict)
+      S += " restrict";
+
+    if (RefQual == FrefQualLValue)
+      S += " &";
+    else if (RefQual == FrefQualRValue)
+      S += " &&";
+
+    if (Attrs != nullptr)
+      Attrs->print(S);
+  }
+};
+
+class LiteralOperator : public Node {
+  const Node *OpName;
+
+public:
+  LiteralOperator(const Node *OpName_)
+      : Node(KLiteralOperator), OpName(OpName_) {}
+
+  template<typename Fn> void match(Fn F) const { F(OpName); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "operator\"\" ";
+    OpName->print(S);
+  }
+};
+
+class SpecialName final : public Node {
+  const StringView Special;
+  const Node *Child;
+
+public:
+  SpecialName(StringView Special_, const Node *Child_)
+      : Node(KSpecialName), Special(Special_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Special, Child); }
+
+  void printLeft(OutputStream &S) const override {
+    S += Special;
+    Child->print(S);
+  }
+};
+
+class CtorVtableSpecialName final : public Node {
+  const Node *FirstType;
+  const Node *SecondType;
+
+public:
+  CtorVtableSpecialName(const Node *FirstType_, const Node *SecondType_)
+      : Node(KCtorVtableSpecialName),
+        FirstType(FirstType_), SecondType(SecondType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(FirstType, SecondType); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "construction vtable for ";
+    FirstType->print(S);
+    S += "-in-";
+    SecondType->print(S);
+  }
+};
+
+struct NestedName : Node {
+  Node *Qual;
+  Node *Name;
+
+  NestedName(Node *Qual_, Node *Name_)
+      : Node(KNestedName), Qual(Qual_), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Qual, Name); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputStream &S) const override {
+    Qual->print(S);
+    S += "::";
+    Name->print(S);
+  }
+};
+
+struct LocalName : Node {
+  Node *Encoding;
+  Node *Entity;
+
+  LocalName(Node *Encoding_, Node *Entity_)
+      : Node(KLocalName), Encoding(Encoding_), Entity(Entity_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Encoding, Entity); }
+
+  void printLeft(OutputStream &S) const override {
+    Encoding->print(S);
+    S += "::";
+    Entity->print(S);
+  }
+};
+
+class QualifiedName final : public Node {
+  // qualifier::name
+  const Node *Qualifier;
+  const Node *Name;
+
+public:
+  QualifiedName(const Node *Qualifier_, const Node *Name_)
+      : Node(KQualifiedName), Qualifier(Qualifier_), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Qualifier, Name); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputStream &S) const override {
+    Qualifier->print(S);
+    S += "::";
+    Name->print(S);
+  }
+};
+
+class VectorType final : public Node {
+  const Node *BaseType;
+  const Node *Dimension;
+
+public:
+  VectorType(const Node *BaseType_, Node *Dimension_)
+      : Node(KVectorType), BaseType(BaseType_),
+        Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(BaseType, Dimension); }
+
+  void printLeft(OutputStream &S) const override {
+    BaseType->print(S);
+    S += " vector[";
+    if (Dimension)
+      Dimension->print(S);
+    S += "]";
+  }
+};
+
+class PixelVectorType final : public Node {
+  const Node *Dimension;
+
+public:
+  PixelVectorType(const Node *Dimension_)
+      : Node(KPixelVectorType), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Dimension); }
+
+  void printLeft(OutputStream &S) const override {
+    // FIXME: This should demangle as "vector pixel".
+    S += "pixel vector[";
+    Dimension->print(S);
+    S += "]";
+  }
+};
+
+enum class TemplateParamKind { Type, NonType, Template };
+
+/// An invented name for a template parameter for which we don't have a
+/// corresponding template argument.
+///
+/// This node is created when parsing the <lambda-sig> for a lambda with
+/// explicit template arguments, which might be referenced in the parameter
+/// types appearing later in the <lambda-sig>.
+class SyntheticTemplateParamName final : public Node {
+  TemplateParamKind Kind;
+  unsigned Index;
+
+public:
+  SyntheticTemplateParamName(TemplateParamKind Kind_, unsigned Index_)
+      : Node(KSyntheticTemplateParamName), Kind(Kind_), Index(Index_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Kind, Index); }
+
+  void printLeft(OutputStream &S) const override {
+    switch (Kind) {
+    case TemplateParamKind::Type:
+      S += "$T";
+      break;
+    case TemplateParamKind::NonType:
+      S += "$N";
+      break;
+    case TemplateParamKind::Template:
+      S += "$TT";
+      break;
+    }
+    if (Index > 0)
+      S << Index - 1;
+  }
+};
+
+/// A template type parameter declaration, 'typename T'.
+class TypeTemplateParamDecl final : public Node {
+  Node *Name;
+
+public:
+  TypeTemplateParamDecl(Node *Name_)
+      : Node(KTypeTemplateParamDecl, Cache::Yes), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "typename ";
+  }
+
+  void printRight(OutputStream &S) const override {
+    Name->print(S);
+  }
+};
+
+/// A non-type template parameter declaration, 'int N'.
+class NonTypeTemplateParamDecl final : public Node {
+  Node *Name;
+  Node *Type;
+
+public:
+  NonTypeTemplateParamDecl(Node *Name_, Node *Type_)
+      : Node(KNonTypeTemplateParamDecl, Cache::Yes), Name(Name_), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, Type); }
+
+  void printLeft(OutputStream &S) const override {
+    Type->printLeft(S);
+    if (!Type->hasRHSComponent(S))
+      S += " ";
+  }
+
+  void printRight(OutputStream &S) const override {
+    Name->print(S);
+    Type->printRight(S);
+  }
+};
+
+/// A template template parameter declaration,
+/// 'template<typename T> typename N'.
+class TemplateTemplateParamDecl final : public Node {
+  Node *Name;
+  NodeArray Params;
+
+public:
+  TemplateTemplateParamDecl(Node *Name_, NodeArray Params_)
+      : Node(KTemplateTemplateParamDecl, Cache::Yes), Name(Name_),
+        Params(Params_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, Params); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "template<";
+    Params.printWithComma(S);
+    S += "> typename ";
+  }
+
+  void printRight(OutputStream &S) const override {
+    Name->print(S);
+  }
+};
+
+/// A template parameter pack declaration, 'typename ...T'.
+class TemplateParamPackDecl final : public Node {
+  Node *Param;
+
+public:
+  TemplateParamPackDecl(Node *Param_)
+      : Node(KTemplateParamPackDecl, Cache::Yes), Param(Param_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Param); }
+
+  void printLeft(OutputStream &S) const override {
+    Param->printLeft(S);
+    S += "...";
+  }
+
+  void printRight(OutputStream &S) const override {
+    Param->printRight(S);
+  }
+};
+
+/// An unexpanded parameter pack (either in the expression or type context). If
+/// this AST is correct, this node will have a ParameterPackExpansion node above
+/// it.
+///
+/// This node is created when some <template-args> are found that apply to an
+/// <encoding>, and is stored in the TemplateParams table. In order for this to
+/// appear in the final AST, it has to referenced via a <template-param> (ie,
+/// T_).
+class ParameterPack final : public Node {
+  NodeArray Data;
+
+  // Setup OutputStream for a pack expansion unless we're already expanding one.
+  void initializePackExpansion(OutputStream &S) const {
+    if (S.CurrentPackMax == std::numeric_limits<unsigned>::max()) {
+      S.CurrentPackMax = static_cast<unsigned>(Data.size());
+      S.CurrentPackIndex = 0;
+    }
+  }
+
+public:
+  ParameterPack(NodeArray Data_) : Node(KParameterPack), Data(Data_) {
+    ArrayCache = FunctionCache = RHSComponentCache = Cache::Unknown;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->ArrayCache == Cache::No;
+        }))
+      ArrayCache = Cache::No;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->FunctionCache == Cache::No;
+        }))
+      FunctionCache = Cache::No;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->RHSComponentCache == Cache::No;
+        }))
+      RHSComponentCache = Cache::No;
+  }
+
+  template<typename Fn> void match(Fn F) const { F(Data); }
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasRHSComponent(S);
+  }
+  bool hasArraySlow(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasArray(S);
+  }
+  bool hasFunctionSlow(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasFunction(S);
+  }
+  const Node *getSyntaxNode(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    return Idx < Data.size() ? Data[Idx]->getSyntaxNode(S) : this;
+  }
+
+  void printLeft(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    if (Idx < Data.size())
+      Data[Idx]->printLeft(S);
+  }
+  void printRight(OutputStream &S) const override {
+    initializePackExpansion(S);
+    size_t Idx = S.CurrentPackIndex;
+    if (Idx < Data.size())
+      Data[Idx]->printRight(S);
+  }
+};
+
+/// A variadic template argument. This node represents an occurrence of
+/// J<something>E in some <template-args>. It isn't itself unexpanded, unless
+/// one of it's Elements is. The parser inserts a ParameterPack into the
+/// TemplateParams table if the <template-args> this pack belongs to apply to an
+/// <encoding>.
+class TemplateArgumentPack final : public Node {
+  NodeArray Elements;
+public:
+  TemplateArgumentPack(NodeArray Elements_)
+      : Node(KTemplateArgumentPack), Elements(Elements_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Elements); }
+
+  NodeArray getElements() const { return Elements; }
+
+  void printLeft(OutputStream &S) const override {
+    Elements.printWithComma(S);
+  }
+};
+
+/// A pack expansion. Below this node, there are some unexpanded ParameterPacks
+/// which each have Child->ParameterPackSize elements.
+class ParameterPackExpansion final : public Node {
+  const Node *Child;
+
+public:
+  ParameterPackExpansion(const Node *Child_)
+      : Node(KParameterPackExpansion), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child); }
+
+  const Node *getChild() const { return Child; }
+
+  void printLeft(OutputStream &S) const override {
+    constexpr unsigned Max = std::numeric_limits<unsigned>::max();
+    SwapAndRestore<unsigned> SavePackIdx(S.CurrentPackIndex, Max);
+    SwapAndRestore<unsigned> SavePackMax(S.CurrentPackMax, Max);
+    size_t StreamPos = S.getCurrentPosition();
+
+    // Print the first element in the pack. If Child contains a ParameterPack,
+    // it will set up S.CurrentPackMax and print the first element.
+    Child->print(S);
+
+    // No ParameterPack was found in Child. This can occur if we've found a pack
+    // expansion on a <function-param>.
+    if (S.CurrentPackMax == Max) {
+      S += "...";
+      return;
+    }
+
+    // We found a ParameterPack, but it has no elements. Erase whatever we may
+    // of printed.
+    if (S.CurrentPackMax == 0) {
+      S.setCurrentPosition(StreamPos);
+      return;
+    }
+
+    // Else, iterate through the rest of the elements in the pack.
+    for (unsigned I = 1, E = S.CurrentPackMax; I < E; ++I) {
+      S += ", ";
+      S.CurrentPackIndex = I;
+      Child->print(S);
+    }
+  }
+};
+
+class TemplateArgs final : public Node {
+  NodeArray Params;
+
+public:
+  TemplateArgs(NodeArray Params_) : Node(KTemplateArgs), Params(Params_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Params); }
+
+  NodeArray getParams() { return Params; }
+
+  void printLeft(OutputStream &S) const override {
+    S += "<";
+    Params.printWithComma(S);
+    if (S.back() == '>')
+      S += " ";
+    S += ">";
+  }
+};
+
+/// A forward-reference to a template argument that was not known at the point
+/// where the template parameter name was parsed in a mangling.
+///
+/// This is created when demangling the name of a specialization of a
+/// conversion function template:
+///
+/// \code
+/// struct A {
+///   template<typename T> operator T*();
+/// };
+/// \endcode
+///
+/// When demangling a specialization of the conversion function template, we
+/// encounter the name of the template (including the \c T) before we reach
+/// the template argument list, so we cannot substitute the parameter name
+/// for the corresponding argument while parsing. Instead, we create a
+/// \c ForwardTemplateReference node that is resolved after we parse the
+/// template arguments.
+struct ForwardTemplateReference : Node {
+  size_t Index;
+  Node *Ref = nullptr;
+
+  // If we're currently printing this node. It is possible (though invalid) for
+  // a forward template reference to refer to itself via a substitution. This
+  // creates a cyclic AST, which will stack overflow printing. To fix this, bail
+  // out if more than one print* function is active.
+  mutable bool Printing = false;
+
+  ForwardTemplateReference(size_t Index_)
+      : Node(KForwardTemplateReference, Cache::Unknown, Cache::Unknown,
+             Cache::Unknown),
+        Index(Index_) {}
+
+  // We don't provide a matcher for these, because the value of the node is
+  // not determined by its construction parameters, and it generally needs
+  // special handling.
+  template<typename Fn> void match(Fn F) const = delete;
+
+  bool hasRHSComponentSlow(OutputStream &S) const override {
+    if (Printing)
+      return false;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    return Ref->hasRHSComponent(S);
+  }
+  bool hasArraySlow(OutputStream &S) const override {
+    if (Printing)
+      return false;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    return Ref->hasArray(S);
+  }
+  bool hasFunctionSlow(OutputStream &S) const override {
+    if (Printing)
+      return false;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    return Ref->hasFunction(S);
+  }
+  const Node *getSyntaxNode(OutputStream &S) const override {
+    if (Printing)
+      return this;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    return Ref->getSyntaxNode(S);
+  }
+
+  void printLeft(OutputStream &S) const override {
+    if (Printing)
+      return;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    Ref->printLeft(S);
+  }
+  void printRight(OutputStream &S) const override {
+    if (Printing)
+      return;
+    SwapAndRestore<bool> SavePrinting(Printing, true);
+    Ref->printRight(S);
+  }
+};
+
+struct NameWithTemplateArgs : Node {
+  // name<template_args>
+  Node *Name;
+  Node *TemplateArgs;
+
+  NameWithTemplateArgs(Node *Name_, Node *TemplateArgs_)
+      : Node(KNameWithTemplateArgs), Name(Name_), TemplateArgs(TemplateArgs_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, TemplateArgs); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputStream &S) const override {
+    Name->print(S);
+    TemplateArgs->print(S);
+  }
+};
+
+class GlobalQualifiedName final : public Node {
+  Node *Child;
+
+public:
+  GlobalQualifiedName(Node* Child_)
+      : Node(KGlobalQualifiedName), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child); }
+
+  StringView getBaseName() const override { return Child->getBaseName(); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "::";
+    Child->print(S);
+  }
+};
+
+struct StdQualifiedName : Node {
+  Node *Child;
+
+  StdQualifiedName(Node *Child_) : Node(KStdQualifiedName), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child); }
+
+  StringView getBaseName() const override { return Child->getBaseName(); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "std::";
+    Child->print(S);
+  }
+};
+
+enum class SpecialSubKind {
+  allocator,
+  basic_string,
+  string,
+  istream,
+  ostream,
+  iostream,
+};
+
+class ExpandedSpecialSubstitution final : public Node {
+  SpecialSubKind SSK;
+
+public:
+  ExpandedSpecialSubstitution(SpecialSubKind SSK_)
+      : Node(KExpandedSpecialSubstitution), SSK(SSK_) {}
+
+  template<typename Fn> void match(Fn F) const { F(SSK); }
+
+  StringView getBaseName() const override {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      return StringView("allocator");
+    case SpecialSubKind::basic_string:
+      return StringView("basic_string");
+    case SpecialSubKind::string:
+      return StringView("basic_string");
+    case SpecialSubKind::istream:
+      return StringView("basic_istream");
+    case SpecialSubKind::ostream:
+      return StringView("basic_ostream");
+    case SpecialSubKind::iostream:
+      return StringView("basic_iostream");
+    }
+    DEMANGLE_UNREACHABLE;
+  }
+
+  void printLeft(OutputStream &S) const override {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      S += "std::allocator";
+      break;
+    case SpecialSubKind::basic_string:
+      S += "std::basic_string";
+      break;
+    case SpecialSubKind::string:
+      S += "std::basic_string<char, std::char_traits<char>, "
+           "std::allocator<char> >";
+      break;
+    case SpecialSubKind::istream:
+      S += "std::basic_istream<char, std::char_traits<char> >";
+      break;
+    case SpecialSubKind::ostream:
+      S += "std::basic_ostream<char, std::char_traits<char> >";
+      break;
+    case SpecialSubKind::iostream:
+      S += "std::basic_iostream<char, std::char_traits<char> >";
+      break;
+    }
+  }
+};
+
+class SpecialSubstitution final : public Node {
+public:
+  SpecialSubKind SSK;
+
+  SpecialSubstitution(SpecialSubKind SSK_)
+      : Node(KSpecialSubstitution), SSK(SSK_) {}
+
+  template<typename Fn> void match(Fn F) const { F(SSK); }
+
+  StringView getBaseName() const override {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      return StringView("allocator");
+    case SpecialSubKind::basic_string:
+      return StringView("basic_string");
+    case SpecialSubKind::string:
+      return StringView("string");
+    case SpecialSubKind::istream:
+      return StringView("istream");
+    case SpecialSubKind::ostream:
+      return StringView("ostream");
+    case SpecialSubKind::iostream:
+      return StringView("iostream");
+    }
+    DEMANGLE_UNREACHABLE;
+  }
+
+  void printLeft(OutputStream &S) const override {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      S += "std::allocator";
+      break;
+    case SpecialSubKind::basic_string:
+      S += "std::basic_string";
+      break;
+    case SpecialSubKind::string:
+      S += "std::string";
+      break;
+    case SpecialSubKind::istream:
+      S += "std::istream";
+      break;
+    case SpecialSubKind::ostream:
+      S += "std::ostream";
+      break;
+    case SpecialSubKind::iostream:
+      S += "std::iostream";
+      break;
+    }
+  }
+};
+
+class CtorDtorName final : public Node {
+  const Node *Basename;
+  const bool IsDtor;
+  const int Variant;
+
+public:
+  CtorDtorName(const Node *Basename_, bool IsDtor_, int Variant_)
+      : Node(KCtorDtorName), Basename(Basename_), IsDtor(IsDtor_),
+        Variant(Variant_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Basename, IsDtor, Variant); }
+
+  void printLeft(OutputStream &S) const override {
+    if (IsDtor)
+      S += "~";
+    S += Basename->getBaseName();
+  }
+};
+
+class DtorName : public Node {
+  const Node *Base;
+
+public:
+  DtorName(const Node *Base_) : Node(KDtorName), Base(Base_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "~";
+    Base->printLeft(S);
+  }
+};
+
+class UnnamedTypeName : public Node {
+  const StringView Count;
+
+public:
+  UnnamedTypeName(StringView Count_) : Node(KUnnamedTypeName), Count(Count_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Count); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "'unnamed";
+    S += Count;
+    S += "\'";
+  }
+};
+
+class ClosureTypeName : public Node {
+  NodeArray TemplateParams;
+  NodeArray Params;
+  StringView Count;
+
+public:
+  ClosureTypeName(NodeArray TemplateParams_, NodeArray Params_,
+                  StringView Count_)
+      : Node(KClosureTypeName), TemplateParams(TemplateParams_),
+        Params(Params_), Count(Count_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(TemplateParams, Params, Count);
+  }
+
+  void printDeclarator(OutputStream &S) const {
+    if (!TemplateParams.empty()) {
+      S += "<";
+      TemplateParams.printWithComma(S);
+      S += ">";
+    }
+    S += "(";
+    Params.printWithComma(S);
+    S += ")";
+  }
+
+  void printLeft(OutputStream &S) const override {
+    S += "\'lambda";
+    S += Count;
+    S += "\'";
+    printDeclarator(S);
+  }
+};
+
+class StructuredBindingName : public Node {
+  NodeArray Bindings;
+public:
+  StructuredBindingName(NodeArray Bindings_)
+      : Node(KStructuredBindingName), Bindings(Bindings_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Bindings); }
+
+  void printLeft(OutputStream &S) const override {
+    S += '[';
+    Bindings.printWithComma(S);
+    S += ']';
+  }
+};
+
+// -- Expression Nodes --
+
+class BinaryExpr : public Node {
+  const Node *LHS;
+  const StringView InfixOperator;
+  const Node *RHS;
+
+public:
+  BinaryExpr(const Node *LHS_, StringView InfixOperator_, const Node *RHS_)
+      : Node(KBinaryExpr), LHS(LHS_), InfixOperator(InfixOperator_), RHS(RHS_) {
+  }
+
+  template<typename Fn> void match(Fn F) const { F(LHS, InfixOperator, RHS); }
+
+  void printLeft(OutputStream &S) const override {
+    // might be a template argument expression, then we need to disambiguate
+    // with parens.
+    if (InfixOperator == ">")
+      S += "(";
+
+    S += "(";
+    LHS->print(S);
+    S += ") ";
+    S += InfixOperator;
+    S += " (";
+    RHS->print(S);
+    S += ")";
+
+    if (InfixOperator == ">")
+      S += ")";
+  }
+};
+
+class ArraySubscriptExpr : public Node {
+  const Node *Op1;
+  const Node *Op2;
+
+public:
+  ArraySubscriptExpr(const Node *Op1_, const Node *Op2_)
+      : Node(KArraySubscriptExpr), Op1(Op1_), Op2(Op2_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Op1, Op2); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "(";
+    Op1->print(S);
+    S += ")[";
+    Op2->print(S);
+    S += "]";
+  }
+};
+
+class PostfixExpr : public Node {
+  const Node *Child;
+  const StringView Operator;
+
+public:
+  PostfixExpr(const Node *Child_, StringView Operator_)
+      : Node(KPostfixExpr), Child(Child_), Operator(Operator_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child, Operator); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "(";
+    Child->print(S);
+    S += ")";
+    S += Operator;
+  }
+};
+
+class ConditionalExpr : public Node {
+  const Node *Cond;
+  const Node *Then;
+  const Node *Else;
+
+public:
+  ConditionalExpr(const Node *Cond_, const Node *Then_, const Node *Else_)
+      : Node(KConditionalExpr), Cond(Cond_), Then(Then_), Else(Else_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Cond, Then, Else); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "(";
+    Cond->print(S);
+    S += ") ? (";
+    Then->print(S);
+    S += ") : (";
+    Else->print(S);
+    S += ")";
+  }
+};
+
+class MemberExpr : public Node {
+  const Node *LHS;
+  const StringView Kind;
+  const Node *RHS;
+
+public:
+  MemberExpr(const Node *LHS_, StringView Kind_, const Node *RHS_)
+      : Node(KMemberExpr), LHS(LHS_), Kind(Kind_), RHS(RHS_) {}
+
+  template<typename Fn> void match(Fn F) const { F(LHS, Kind, RHS); }
+
+  void printLeft(OutputStream &S) const override {
+    LHS->print(S);
+    S += Kind;
+    RHS->print(S);
+  }
+};
+
+class EnclosingExpr : public Node {
+  const StringView Prefix;
+  const Node *Infix;
+  const StringView Postfix;
+
+public:
+  EnclosingExpr(StringView Prefix_, Node *Infix_, StringView Postfix_)
+      : Node(KEnclosingExpr), Prefix(Prefix_), Infix(Infix_),
+        Postfix(Postfix_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Prefix, Infix, Postfix); }
+
+  void printLeft(OutputStream &S) const override {
+    S += Prefix;
+    Infix->print(S);
+    S += Postfix;
+  }
+};
+
+class CastExpr : public Node {
+  // cast_kind<to>(from)
+  const StringView CastKind;
+  const Node *To;
+  const Node *From;
+
+public:
+  CastExpr(StringView CastKind_, const Node *To_, const Node *From_)
+      : Node(KCastExpr), CastKind(CastKind_), To(To_), From(From_) {}
+
+  template<typename Fn> void match(Fn F) const { F(CastKind, To, From); }
+
+  void printLeft(OutputStream &S) const override {
+    S += CastKind;
+    S += "<";
+    To->printLeft(S);
+    S += ">(";
+    From->printLeft(S);
+    S += ")";
+  }
+};
+
+class SizeofParamPackExpr : public Node {
+  const Node *Pack;
+
+public:
+  SizeofParamPackExpr(const Node *Pack_)
+      : Node(KSizeofParamPackExpr), Pack(Pack_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Pack); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "sizeof...(";
+    ParameterPackExpansion PPE(Pack);
+    PPE.printLeft(S);
+    S += ")";
+  }
+};
+
+class CallExpr : public Node {
+  const Node *Callee;
+  NodeArray Args;
+
+public:
+  CallExpr(const Node *Callee_, NodeArray Args_)
+      : Node(KCallExpr), Callee(Callee_), Args(Args_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Callee, Args); }
+
+  void printLeft(OutputStream &S) const override {
+    Callee->print(S);
+    S += "(";
+    Args.printWithComma(S);
+    S += ")";
+  }
+};
+
+class NewExpr : public Node {
+  // new (expr_list) type(init_list)
+  NodeArray ExprList;
+  Node *Type;
+  NodeArray InitList;
+  bool IsGlobal; // ::operator new ?
+  bool IsArray;  // new[] ?
+public:
+  NewExpr(NodeArray ExprList_, Node *Type_, NodeArray InitList_, bool IsGlobal_,
+          bool IsArray_)
+      : Node(KNewExpr), ExprList(ExprList_), Type(Type_), InitList(InitList_),
+        IsGlobal(IsGlobal_), IsArray(IsArray_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(ExprList, Type, InitList, IsGlobal, IsArray);
+  }
+
+  void printLeft(OutputStream &S) const override {
+    if (IsGlobal)
+      S += "::operator ";
+    S += "new";
+    if (IsArray)
+      S += "[]";
+    S += ' ';
+    if (!ExprList.empty()) {
+      S += "(";
+      ExprList.printWithComma(S);
+      S += ")";
+    }
+    Type->print(S);
+    if (!InitList.empty()) {
+      S += "(";
+      InitList.printWithComma(S);
+      S += ")";
+    }
+
+  }
+};
+
+class DeleteExpr : public Node {
+  Node *Op;
+  bool IsGlobal;
+  bool IsArray;
+
+public:
+  DeleteExpr(Node *Op_, bool IsGlobal_, bool IsArray_)
+      : Node(KDeleteExpr), Op(Op_), IsGlobal(IsGlobal_), IsArray(IsArray_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Op, IsGlobal, IsArray); }
+
+  void printLeft(OutputStream &S) const override {
+    if (IsGlobal)
+      S += "::";
+    S += "delete";
+    if (IsArray)
+      S += "[] ";
+    Op->print(S);
+  }
+};
+
+class PrefixExpr : public Node {
+  StringView Prefix;
+  Node *Child;
+
+public:
+  PrefixExpr(StringView Prefix_, Node *Child_)
+      : Node(KPrefixExpr), Prefix(Prefix_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Prefix, Child); }
+
+  void printLeft(OutputStream &S) const override {
+    S += Prefix;
+    S += "(";
+    Child->print(S);
+    S += ")";
+  }
+};
+
+class FunctionParam : public Node {
+  StringView Number;
+
+public:
+  FunctionParam(StringView Number_) : Node(KFunctionParam), Number(Number_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Number); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "fp";
+    S += Number;
+  }
+};
+
+class ConversionExpr : public Node {
+  const Node *Type;
+  NodeArray Expressions;
+
+public:
+  ConversionExpr(const Node *Type_, NodeArray Expressions_)
+      : Node(KConversionExpr), Type(Type_), Expressions(Expressions_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type, Expressions); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "(";
+    Type->print(S);
+    S += ")(";
+    Expressions.printWithComma(S);
+    S += ")";
+  }
+};
+
+class InitListExpr : public Node {
+  const Node *Ty;
+  NodeArray Inits;
+public:
+  InitListExpr(const Node *Ty_, NodeArray Inits_)
+      : Node(KInitListExpr), Ty(Ty_), Inits(Inits_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Inits); }
+
+  void printLeft(OutputStream &S) const override {
+    if (Ty)
+      Ty->print(S);
+    S += '{';
+    Inits.printWithComma(S);
+    S += '}';
+  }
+};
+
+class BracedExpr : public Node {
+  const Node *Elem;
+  const Node *Init;
+  bool IsArray;
+public:
+  BracedExpr(const Node *Elem_, const Node *Init_, bool IsArray_)
+      : Node(KBracedExpr), Elem(Elem_), Init(Init_), IsArray(IsArray_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Elem, Init, IsArray); }
+
+  void printLeft(OutputStream &S) const override {
+    if (IsArray) {
+      S += '[';
+      Elem->print(S);
+      S += ']';
+    } else {
+      S += '.';
+      Elem->print(S);
+    }
+    if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
+      S += " = ";
+    Init->print(S);
+  }
+};
+
+class BracedRangeExpr : public Node {
+  const Node *First;
+  const Node *Last;
+  const Node *Init;
+public:
+  BracedRangeExpr(const Node *First_, const Node *Last_, const Node *Init_)
+      : Node(KBracedRangeExpr), First(First_), Last(Last_), Init(Init_) {}
+
+  template<typename Fn> void match(Fn F) const { F(First, Last, Init); }
+
+  void printLeft(OutputStream &S) const override {
+    S += '[';
+    First->print(S);
+    S += " ... ";
+    Last->print(S);
+    S += ']';
+    if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
+      S += " = ";
+    Init->print(S);
+  }
+};
+
+class FoldExpr : public Node {
+  const Node *Pack, *Init;
+  StringView OperatorName;
+  bool IsLeftFold;
+
+public:
+  FoldExpr(bool IsLeftFold_, StringView OperatorName_, const Node *Pack_,
+           const Node *Init_)
+      : Node(KFoldExpr), Pack(Pack_), Init(Init_), OperatorName(OperatorName_),
+        IsLeftFold(IsLeftFold_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(IsLeftFold, OperatorName, Pack, Init);
+  }
+
+  void printLeft(OutputStream &S) const override {
+    auto PrintPack = [&] {
+      S += '(';
+      ParameterPackExpansion(Pack).print(S);
+      S += ')';
+    };
+
+    S += '(';
+
+    if (IsLeftFold) {
+      // init op ... op pack
+      if (Init != nullptr) {
+        Init->print(S);
+        S += ' ';
+        S += OperatorName;
+        S += ' ';
+      }
+      // ... op pack
+      S += "... ";
+      S += OperatorName;
+      S += ' ';
+      PrintPack();
+    } else { // !IsLeftFold
+      // pack op ...
+      PrintPack();
+      S += ' ';
+      S += OperatorName;
+      S += " ...";
+      // pack op ... op init
+      if (Init != nullptr) {
+        S += ' ';
+        S += OperatorName;
+        S += ' ';
+        Init->print(S);
+      }
+    }
+    S += ')';
+  }
+};
+
+class ThrowExpr : public Node {
+  const Node *Op;
+
+public:
+  ThrowExpr(const Node *Op_) : Node(KThrowExpr), Op(Op_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Op); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "throw ";
+    Op->print(S);
+  }
+};
+
+// MSVC __uuidof extension, generated by clang in -fms-extensions mode.
+class UUIDOfExpr : public Node {
+  Node *Operand;
+public:
+  UUIDOfExpr(Node *Operand_) : Node(KUUIDOfExpr), Operand(Operand_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Operand); }
+
+  void printLeft(OutputStream &S) const override {
+    S << "__uuidof(";
+    Operand->print(S);
+    S << ")";
+  }
+};
+
+class BoolExpr : public Node {
+  bool Value;
+
+public:
+  BoolExpr(bool Value_) : Node(KBoolExpr), Value(Value_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Value); }
+
+  void printLeft(OutputStream &S) const override {
+    S += Value ? StringView("true") : StringView("false");
+  }
+};
+
+class StringLiteral : public Node {
+  const Node *Type;
+
+public:
+  StringLiteral(const Node *Type_) : Node(KStringLiteral), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "\"<";
+    Type->print(S);
+    S += ">\"";
+  }
+};
+
+class LambdaExpr : public Node {
+  const Node *Type;
+
+public:
+  LambdaExpr(const Node *Type_) : Node(KLambdaExpr), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "[]";
+    if (Type->getKind() == KClosureTypeName)
+      static_cast<const ClosureTypeName *>(Type)->printDeclarator(S);
+    S += "{...}";
+  }
+};
+
+class IntegerCastExpr : public Node {
+  // ty(integer)
+  const Node *Ty;
+  StringView Integer;
+
+public:
+  IntegerCastExpr(const Node *Ty_, StringView Integer_)
+      : Node(KIntegerCastExpr), Ty(Ty_), Integer(Integer_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Integer); }
+
+  void printLeft(OutputStream &S) const override {
+    S += "(";
+    Ty->print(S);
+    S += ")";
+    S += Integer;
+  }
+};
+
+class IntegerLiteral : public Node {
+  StringView Type;
+  StringView Value;
+
+public:
+  IntegerLiteral(StringView Type_, StringView Value_)
+      : Node(KIntegerLiteral), Type(Type_), Value(Value_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type, Value); }
+
+  void printLeft(OutputStream &S) const override {
+    if (Type.size() > 3) {
+      S += "(";
+      S += Type;
+      S += ")";
+    }
+
+    if (Value[0] == 'n') {
+      S += "-";
+      S += Value.dropFront(1);
+    } else
+      S += Value;
+
+    if (Type.size() <= 3)
+      S += Type;
+  }
+};
+
+template <class Float> struct FloatData;
+
+namespace float_literal_impl {
+constexpr Node::Kind getFloatLiteralKind(float *) {
+  return Node::KFloatLiteral;
+}
+constexpr Node::Kind getFloatLiteralKind(double *) {
+  return Node::KDoubleLiteral;
+}
+constexpr Node::Kind getFloatLiteralKind(long double *) {
+  return Node::KLongDoubleLiteral;
+}
+}
+
+template <class Float> class FloatLiteralImpl : public Node {
+  const StringView Contents;
+
+  static constexpr Kind KindForClass =
+      float_literal_impl::getFloatLiteralKind((Float *)nullptr);
+
+public:
+  FloatLiteralImpl(StringView Contents_)
+      : Node(KindForClass), Contents(Contents_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Contents); }
+
+  void printLeft(OutputStream &s) const override {
+    const char *first = Contents.begin();
+    const char *last = Contents.end() + 1;
+
+    const size_t N = FloatData<Float>::mangled_size;
+    if (static_cast<std::size_t>(last - first) > N) {
+      last = first + N;
+      union {
+        Float value;
+        char buf[sizeof(Float)];
+      };
+      const char *t = first;
+      char *e = buf;
+      for (; t != last; ++t, ++e) {
+        unsigned d1 = isdigit(*t) ? static_cast<unsigned>(*t - '0')
+                                  : static_cast<unsigned>(*t - 'a' + 10);
+        ++t;
+        unsigned d0 = isdigit(*t) ? static_cast<unsigned>(*t - '0')
+                                  : static_cast<unsigned>(*t - 'a' + 10);
+        *e = static_cast<char>((d1 << 4) + d0);
+      }
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+      std::reverse(buf, e);
+#endif
+      char num[FloatData<Float>::max_demangled_size] = {0};
+      int n = snprintf(num, sizeof(num), FloatData<Float>::spec, value);
+      s += StringView(num, num + n);
+    }
+  }
+};
+
+using FloatLiteral = FloatLiteralImpl<float>;
+using DoubleLiteral = FloatLiteralImpl<double>;
+using LongDoubleLiteral = FloatLiteralImpl<long double>;
+
+/// Visit the node. Calls \c F(P), where \c P is the node cast to the
+/// appropriate derived class.
+template<typename Fn>
+void Node::visit(Fn F) const {
+  switch (K) {
+#define CASE(X) case K ## X: return F(static_cast<const X*>(this));
+    FOR_EACH_NODE_KIND(CASE)
+#undef CASE
+  }
+  assert(0 && "unknown mangling node kind");
+}
+
+/// Determine the kind of a node from its type.
+template<typename NodeT> struct NodeKind;
+#define SPECIALIZATION(X) \
+  template<> struct NodeKind<X> { \
+    static constexpr Node::Kind Kind = Node::K##X; \
+    static constexpr const char *name() { return #X; } \
+  };
+FOR_EACH_NODE_KIND(SPECIALIZATION)
+#undef SPECIALIZATION
+
+#undef FOR_EACH_NODE_KIND
+
+template <class T, size_t N>
+class PODSmallVector {
+  static_assert(std::is_pod<T>::value,
+                "T is required to be a plain old data type");
+
+  T* First = nullptr;
+  T* Last = nullptr;
+  T* Cap = nullptr;
+  T Inline[N] = {0};
+
+  bool isInline() const { return First == Inline; }
+
+  void clearInline() {
+    First = Inline;
+    Last = Inline;
+    Cap = Inline + N;
+  }
+
+  void reserve(size_t NewCap) {
+    size_t S = size();
+    if (isInline()) {
+      auto* Tmp = static_cast<T*>(std::malloc(NewCap * sizeof(T)));
+      if (Tmp == nullptr)
+        std::terminate();
+      std::copy(First, Last, Tmp);
+      First = Tmp;
+    } else {
+      First = static_cast<T*>(std::realloc(First, NewCap * sizeof(T)));
+      if (First == nullptr)
+        std::terminate();
+    }
+    Last = First + S;
+    Cap = First + NewCap;
+  }
+
+public:
+  PODSmallVector() : First(Inline), Last(First), Cap(Inline + N) {}
+
+  PODSmallVector(const PODSmallVector&) = delete;
+  PODSmallVector& operator=(const PODSmallVector&) = delete;
+
+  PODSmallVector(PODSmallVector&& Other) : PODSmallVector() {
+    if (Other.isInline()) {
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return;
+    }
+
+    First = Other.First;
+    Last = Other.Last;
+    Cap = Other.Cap;
+    Other.clearInline();
+  }
+
+  PODSmallVector& operator=(PODSmallVector&& Other) {
+    if (Other.isInline()) {
+      if (!isInline()) {
+        std::free(First);
+        clearInline();
+      }
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return *this;
+    }
+
+    if (isInline()) {
+      First = Other.First;
+      Last = Other.Last;
+      Cap = Other.Cap;
+      Other.clearInline();
+      return *this;
+    }
+
+    std::swap(First, Other.First);
+    std::swap(Last, Other.Last);
+    std::swap(Cap, Other.Cap);
+    Other.clear();
+    return *this;
+  }
+
+  void push_back(const T& Elem) {
+    if (Last == Cap)
+      reserve(size() * 2);
+    *Last++ = Elem;
+  }
+
+  void pop_back() {
+    assert(Last != First && "Popping empty vector!");
+    --Last;
+  }
+
+  void dropBack(size_t Index) {
+    assert(Index <= size() && "dropBack() can't expand!");
+    Last = First + Index;
+  }
+
+  T* begin() { return First; }
+  T* end() { return Last; }
+
+  bool empty() const { return First == Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  T& back() {
+    assert(Last != First && "Calling back() on empty vector!");
+    return *(Last - 1);
+  }
+  T& operator[](size_t Index) {
+    assert(Index < size() && "Invalid access!");
+    return *(begin() + Index);
+  }
+  void clear() { Last = First; }
+
+  ~PODSmallVector() {
+    if (!isInline())
+      std::free(First);
+  }
+};
+
+template <typename Derived, typename Alloc> struct AbstractManglingParser {
+  const char *First;
+  const char *Last;
+
+  // Name stack, this is used by the parser to hold temporary names that were
+  // parsed. The parser collapses multiple names into new nodes to construct
+  // the AST. Once the parser is finished, names.size() == 1.
+  PODSmallVector<Node *, 32> Names;
+
+  // Substitution table. Itanium supports name substitutions as a means of
+  // compression. The string "S42_" refers to the 44nd entry (base-36) in this
+  // table.
+  PODSmallVector<Node *, 32> Subs;
+
+  using TemplateParamList = PODSmallVector<Node *, 8>;
+
+  class ScopedTemplateParamList {
+    AbstractManglingParser *Parser;
+    size_t OldNumTemplateParamLists;
+    TemplateParamList Params;
+
+  public:
+    ScopedTemplateParamList(AbstractManglingParser *Parser)
+        : Parser(Parser),
+          OldNumTemplateParamLists(Parser->TemplateParams.size()) {
+      Parser->TemplateParams.push_back(&Params);
+    }
+    ~ScopedTemplateParamList() {
+      assert(Parser->TemplateParams.size() >= OldNumTemplateParamLists);
+      Parser->TemplateParams.dropBack(OldNumTemplateParamLists);
+    }
+  };
+
+  // Template parameter table. Like the above, but referenced like "T42_".
+  // This has a smaller size compared to Subs and Names because it can be
+  // stored on the stack.
+  TemplateParamList OuterTemplateParams;
+
+  // Lists of template parameters indexed by template parameter depth,
+  // referenced like "TL2_4_". If nonempty, element 0 is always
+  // OuterTemplateParams; inner elements are always template parameter lists of
+  // lambda expressions. For a generic lambda with no explicit template
+  // parameter list, the corresponding parameter list pointer will be null.
+  PODSmallVector<TemplateParamList *, 4> TemplateParams;
+
+  // Set of unresolved forward <template-param> references. These can occur in a
+  // conversion operator's type, and are resolved in the enclosing <encoding>.
+  PODSmallVector<ForwardTemplateReference *, 4> ForwardTemplateRefs;
+
+  bool TryToParseTemplateArgs = true;
+  bool PermitForwardTemplateReferences = false;
+  size_t ParsingLambdaParamsAtLevel = (size_t)-1;
+
+  unsigned NumSyntheticTemplateParameters[3] = {};
+
+  Alloc ASTAllocator;
+
+  AbstractManglingParser(const char *First_, const char *Last_)
+      : First(First_), Last(Last_) {}
+
+  Derived &getDerived() { return static_cast<Derived &>(*this); }
+
+  void reset(const char *First_, const char *Last_) {
+    First = First_;
+    Last = Last_;
+    Names.clear();
+    Subs.clear();
+    TemplateParams.clear();
+    ParsingLambdaParamsAtLevel = (size_t)-1;
+    TryToParseTemplateArgs = true;
+    PermitForwardTemplateReferences = false;
+    for (int I = 0; I != 3; ++I)
+      NumSyntheticTemplateParameters[I] = 0;
+    ASTAllocator.reset();
+  }
+
+  template <class T, class... Args> Node *make(Args &&... args) {
+    return ASTAllocator.template makeNode<T>(std::forward<Args>(args)...);
+  }
+
+  template <class It> NodeArray makeNodeArray(It begin, It end) {
+    size_t sz = static_cast<size_t>(end - begin);
+    void *mem = ASTAllocator.allocateNodeArray(sz);
+    Node **data = new (mem) Node *[sz];
+    std::copy(begin, end, data);
+    return NodeArray(data, sz);
+  }
+
+  NodeArray popTrailingNodeArray(size_t FromPosition) {
+    assert(FromPosition <= Names.size());
+    NodeArray res =
+        makeNodeArray(Names.begin() + (long)FromPosition, Names.end());
+    Names.dropBack(FromPosition);
+    return res;
+  }
+
+  bool consumeIf(StringView S) {
+    if (StringView(First, Last).startsWith(S)) {
+      First += S.size();
+      return true;
+    }
+    return false;
+  }
+
+  bool consumeIf(char C) {
+    if (First != Last && *First == C) {
+      ++First;
+      return true;
+    }
+    return false;
+  }
+
+  char consume() { return First != Last ? *First++ : '\0'; }
+
+  char look(unsigned Lookahead = 0) {
+    if (static_cast<size_t>(Last - First) <= Lookahead)
+      return '\0';
+    return First[Lookahead];
+  }
+
+  size_t numLeft() const { return static_cast<size_t>(Last - First); }
+
+  StringView parseNumber(bool AllowNegative = false);
+  Qualifiers parseCVQualifiers();
+  bool parsePositiveInteger(size_t *Out);
+  StringView parseBareSourceName();
+
+  bool parseSeqId(size_t *Out);
+  Node *parseSubstitution();
+  Node *parseTemplateParam();
+  Node *parseTemplateParamDecl();
+  Node *parseTemplateArgs(bool TagTemplates = false);
+  Node *parseTemplateArg();
+
+  /// Parse the <expr> production.
+  Node *parseExpr();
+  Node *parsePrefixExpr(StringView Kind);
+  Node *parseBinaryExpr(StringView Kind);
+  Node *parseIntegerLiteral(StringView Lit);
+  Node *parseExprPrimary();
+  template <class Float> Node *parseFloatingLiteral();
+  Node *parseFunctionParam();
+  Node *parseNewExpr();
+  Node *parseConversionExpr();
+  Node *parseBracedExpr();
+  Node *parseFoldExpr();
+
+  /// Parse the <type> production.
+  Node *parseType();
+  Node *parseFunctionType();
+  Node *parseVectorType();
+  Node *parseDecltype();
+  Node *parseArrayType();
+  Node *parsePointerToMemberType();
+  Node *parseClassEnumType();
+  Node *parseQualifiedType();
+
+  Node *parseEncoding();
+  bool parseCallOffset();
+  Node *parseSpecialName();
+
+  /// Holds some extra information about a <name> that is being parsed. This
+  /// information is only pertinent if the <name> refers to an <encoding>.
+  struct NameState {
+    bool CtorDtorConversion = false;
+    bool EndsWithTemplateArgs = false;
+    Qualifiers CVQualifiers = QualNone;
+    FunctionRefQual ReferenceQualifier = FrefQualNone;
+    size_t ForwardTemplateRefsBegin;
+
+    NameState(AbstractManglingParser *Enclosing)
+        : ForwardTemplateRefsBegin(Enclosing->ForwardTemplateRefs.size()) {}
+  };
+
+  bool resolveForwardTemplateRefs(NameState &State) {
+    size_t I = State.ForwardTemplateRefsBegin;
+    size_t E = ForwardTemplateRefs.size();
+    for (; I < E; ++I) {
+      size_t Idx = ForwardTemplateRefs[I]->Index;
+      if (TemplateParams.empty() || !TemplateParams[0] ||
+          Idx >= TemplateParams[0]->size())
+        return true;
+      ForwardTemplateRefs[I]->Ref = (*TemplateParams[0])[Idx];
+    }
+    ForwardTemplateRefs.dropBack(State.ForwardTemplateRefsBegin);
+    return false;
+  }
+
+  /// Parse the <name> production>
+  Node *parseName(NameState *State = nullptr);
+  Node *parseLocalName(NameState *State);
+  Node *parseOperatorName(NameState *State);
+  Node *parseUnqualifiedName(NameState *State);
+  Node *parseUnnamedTypeName(NameState *State);
+  Node *parseSourceName(NameState *State);
+  Node *parseUnscopedName(NameState *State);
+  Node *parseNestedName(NameState *State);
+  Node *parseCtorDtorName(Node *&SoFar, NameState *State);
+
+  Node *parseAbiTags(Node *N);
+
+  /// Parse the <unresolved-name> production.
+  Node *parseUnresolvedName();
+  Node *parseSimpleId();
+  Node *parseBaseUnresolvedName();
+  Node *parseUnresolvedType();
+  Node *parseDestructorName();
+
+  /// Top-level entry point into the parser.
+  Node *parse();
+};
+
+const char* parse_discriminator(const char* first, const char* last);
+
+// <name> ::= <nested-name> // N
+//        ::= <local-name> # See Scope Encoding below  // Z
+//        ::= <unscoped-template-name> <template-args>
+//        ::= <unscoped-name>
+//
+// <unscoped-template-name> ::= <unscoped-name>
+//                          ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseName(NameState *State) {
+  consumeIf('L'); // extension
+
+  if (look() == 'N')
+    return getDerived().parseNestedName(State);
+  if (look() == 'Z')
+    return getDerived().parseLocalName(State);
+
+  //        ::= <unscoped-template-name> <template-args>
+  if (look() == 'S' && look(1) != 't') {
+    Node *S = getDerived().parseSubstitution();
+    if (S == nullptr)
+      return nullptr;
+    if (look() != 'I')
+      return nullptr;
+    Node *TA = getDerived().parseTemplateArgs(State != nullptr);
+    if (TA == nullptr)
+      return nullptr;
+    if (State) State->EndsWithTemplateArgs = true;
+    return make<NameWithTemplateArgs>(S, TA);
+  }
+
+  Node *N = getDerived().parseUnscopedName(State);
+  if (N == nullptr)
+    return nullptr;
+  //        ::= <unscoped-template-name> <template-args>
+  if (look() == 'I') {
+    Subs.push_back(N);
+    Node *TA = getDerived().parseTemplateArgs(State != nullptr);
+    if (TA == nullptr)
+      return nullptr;
+    if (State) State->EndsWithTemplateArgs = true;
+    return make<NameWithTemplateArgs>(N, TA);
+  }
+  //        ::= <unscoped-name>
+  return N;
+}
+
+// <local-name> := Z <function encoding> E <entity name> [<discriminator>]
+//              := Z <function encoding> E s [<discriminator>]
+//              := Z <function encoding> Ed [ <parameter number> ] _ <entity name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseLocalName(NameState *State) {
+  if (!consumeIf('Z'))
+    return nullptr;
+  Node *Encoding = getDerived().parseEncoding();
+  if (Encoding == nullptr || !consumeIf('E'))
+    return nullptr;
+
+  if (consumeIf('s')) {
+    First = parse_discriminator(First, Last);
+    auto *StringLitName = make<NameType>("string literal");
+    if (!StringLitName)
+      return nullptr;
+    return make<LocalName>(Encoding, StringLitName);
+  }
+
+  if (consumeIf('d')) {
+    parseNumber(true);
+    if (!consumeIf('_'))
+      return nullptr;
+    Node *N = getDerived().parseName(State);
+    if (N == nullptr)
+      return nullptr;
+    return make<LocalName>(Encoding, N);
+  }
+
+  Node *Entity = getDerived().parseName(State);
+  if (Entity == nullptr)
+    return nullptr;
+  First = parse_discriminator(First, Last);
+  return make<LocalName>(Encoding, Entity);
+}
+
+// <unscoped-name> ::= <unqualified-name>
+//                 ::= St <unqualified-name>   # ::std::
+// extension       ::= StL<unqualified-name>
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseUnscopedName(NameState *State) {
+  if (consumeIf("StL") || consumeIf("St")) {
+    Node *R = getDerived().parseUnqualifiedName(State);
+    if (R == nullptr)
+      return nullptr;
+    return make<StdQualifiedName>(R);
+  }
+  return getDerived().parseUnqualifiedName(State);
+}
+
+// <unqualified-name> ::= <operator-name> [abi-tags]
+//                    ::= <ctor-dtor-name>
+//                    ::= <source-name>
+//                    ::= <unnamed-type-name>
+//                    ::= DC <source-name>+ E      # structured binding declaration
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseUnqualifiedName(NameState *State) {
+  // <ctor-dtor-name>s are special-cased in parseNestedName().
+  Node *Result;
+  if (look() == 'U')
+    Result = getDerived().parseUnnamedTypeName(State);
+  else if (look() >= '1' && look() <= '9')
+    Result = getDerived().parseSourceName(State);
+  else if (consumeIf("DC")) {
+    size_t BindingsBegin = Names.size();
+    do {
+      Node *Binding = getDerived().parseSourceName(State);
+      if (Binding == nullptr)
+        return nullptr;
+      Names.push_back(Binding);
+    } while (!consumeIf('E'));
+    Result = make<StructuredBindingName>(popTrailingNodeArray(BindingsBegin));
+  } else
+    Result = getDerived().parseOperatorName(State);
+  if (Result != nullptr)
+    Result = getDerived().parseAbiTags(Result);
+  return Result;
+}
+
+// <unnamed-type-name> ::= Ut [<nonnegative number>] _
+//                     ::= <closure-type-name>
+//
+// <closure-type-name> ::= Ul <lambda-sig> E [ <nonnegative number> ] _
+//
+// <lambda-sig> ::= <parameter type>+  # Parameter types or "v" if the lambda has no parameters
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseUnnamedTypeName(NameState *State) {
+  // <template-params> refer to the innermost <template-args>. Clear out any
+  // outer args that we may have inserted into TemplateParams.
+  if (State != nullptr)
+    TemplateParams.clear();
+
+  if (consumeIf("Ut")) {
+    StringView Count = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<UnnamedTypeName>(Count);
+  }
+  if (consumeIf("Ul")) {
+    SwapAndRestore<size_t> SwapParams(ParsingLambdaParamsAtLevel,
+                                      TemplateParams.size());
+    ScopedTemplateParamList LambdaTemplateParams(this);
+
+    size_t ParamsBegin = Names.size();
+    while (look() == 'T' &&
+           StringView("yptn").find(look(1)) != StringView::npos) {
+      Node *T = parseTemplateParamDecl();
+      if (!T)
+        return nullptr;
+      Names.push_back(T);
+    }
+    NodeArray TempParams = popTrailingNodeArray(ParamsBegin);
+
+    // FIXME: If TempParams is empty and none of the function parameters
+    // includes 'auto', we should remove LambdaTemplateParams from the
+    // TemplateParams list. Unfortunately, we don't find out whether there are
+    // any 'auto' parameters until too late in an example such as:
+    //
+    //   template<typename T> void f(
+    //       decltype([](decltype([]<typename T>(T v) {}),
+    //                   auto) {})) {}
+    //   template<typename T> void f(
+    //       decltype([](decltype([]<typename T>(T w) {}),
+    //                   int) {})) {}
+    //
+    // Here, the type of v is at level 2 but the type of w is at level 1. We
+    // don't find this out until we encounter the type of the next parameter.
+    //
+    // However, compilers can't actually cope with the former example in
+    // practice, and it's likely to be made ill-formed in future, so we don't
+    // need to support it here.
+    //
+    // If we encounter an 'auto' in the function parameter types, we will
+    // recreate a template parameter scope for it, but any intervening lambdas
+    // will be parsed in the 'wrong' template parameter depth.
+    if (TempParams.empty())
+      TemplateParams.pop_back();
+
+    if (!consumeIf("vE")) {
+      do {
+        Node *P = getDerived().parseType();
+        if (P == nullptr)
+          return nullptr;
+        Names.push_back(P);
+      } while (!consumeIf('E'));
+    }
+    NodeArray Params = popTrailingNodeArray(ParamsBegin);
+
+    StringView Count = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<ClosureTypeName>(TempParams, Params, Count);
+  }
+  if (consumeIf("Ub")) {
+    (void)parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<NameType>("'block-literal'");
+  }
+  return nullptr;
+}
+
+// <source-name> ::= <positive length number> <identifier>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSourceName(NameState *) {
+  size_t Length = 0;
+  if (parsePositiveInteger(&Length))
+    return nullptr;
+  if (numLeft() < Length || Length == 0)
+    return nullptr;
+  StringView Name(First, First + Length);
+  First += Length;
+  if (Name.startsWith("_GLOBAL__N"))
+    return make<NameType>("(anonymous namespace)");
+  return make<NameType>(Name);
+}
+
+//   <operator-name> ::= aa    # &&
+//                   ::= ad    # & (unary)
+//                   ::= an    # &
+//                   ::= aN    # &=
+//                   ::= aS    # =
+//                   ::= cl    # ()
+//                   ::= cm    # ,
+//                   ::= co    # ~
+//                   ::= cv <type>    # (cast)
+//                   ::= da    # delete[]
+//                   ::= de    # * (unary)
+//                   ::= dl    # delete
+//                   ::= dv    # /
+//                   ::= dV    # /=
+//                   ::= eo    # ^
+//                   ::= eO    # ^=
+//                   ::= eq    # ==
+//                   ::= ge    # >=
+//                   ::= gt    # >
+//                   ::= ix    # []
+//                   ::= le    # <=
+//                   ::= li <source-name>  # operator ""
+//                   ::= ls    # <<
+//                   ::= lS    # <<=
+//                   ::= lt    # <
+//                   ::= mi    # -
+//                   ::= mI    # -=
+//                   ::= ml    # *
+//                   ::= mL    # *=
+//                   ::= mm    # -- (postfix in <expression> context)
+//                   ::= na    # new[]
+//                   ::= ne    # !=
+//                   ::= ng    # - (unary)
+//                   ::= nt    # !
+//                   ::= nw    # new
+//                   ::= oo    # ||
+//                   ::= or    # |
+//                   ::= oR    # |=
+//                   ::= pm    # ->*
+//                   ::= pl    # +
+//                   ::= pL    # +=
+//                   ::= pp    # ++ (postfix in <expression> context)
+//                   ::= ps    # + (unary)
+//                   ::= pt    # ->
+//                   ::= qu    # ?
+//                   ::= rm    # %
+//                   ::= rM    # %=
+//                   ::= rs    # >>
+//                   ::= rS    # >>=
+//                   ::= ss    # <=> C++2a
+//                   ::= v <digit> <source-name>        # vendor extended operator
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseOperatorName(NameState *State) {
+  switch (look()) {
+  case 'a':
+    switch (look(1)) {
+    case 'a':
+      First += 2;
+      return make<NameType>("operator&&");
+    case 'd':
+    case 'n':
+      First += 2;
+      return make<NameType>("operator&");
+    case 'N':
+      First += 2;
+      return make<NameType>("operator&=");
+    case 'S':
+      First += 2;
+      return make<NameType>("operator=");
+    }
+    return nullptr;
+  case 'c':
+    switch (look(1)) {
+    case 'l':
+      First += 2;
+      return make<NameType>("operator()");
+    case 'm':
+      First += 2;
+      return make<NameType>("operator,");
+    case 'o':
+      First += 2;
+      return make<NameType>("operator~");
+    //                   ::= cv <type>    # (cast)
+    case 'v': {
+      First += 2;
+      SwapAndRestore<bool> SaveTemplate(TryToParseTemplateArgs, false);
+      // If we're parsing an encoding, State != nullptr and the conversion
+      // operators' <type> could have a <template-param> that refers to some
+      // <template-arg>s further ahead in the mangled name.
+      SwapAndRestore<bool> SavePermit(PermitForwardTemplateReferences,
+                                      PermitForwardTemplateReferences ||
+                                          State != nullptr);
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      if (State) State->CtorDtorConversion = true;
+      return make<ConversionOperatorType>(Ty);
+    }
+    }
+    return nullptr;
+  case 'd':
+    switch (look(1)) {
+    case 'a':
+      First += 2;
+      return make<NameType>("operator delete[]");
+    case 'e':
+      First += 2;
+      return make<NameType>("operator*");
+    case 'l':
+      First += 2;
+      return make<NameType>("operator delete");
+    case 'v':
+      First += 2;
+      return make<NameType>("operator/");
+    case 'V':
+      First += 2;
+      return make<NameType>("operator/=");
+    }
+    return nullptr;
+  case 'e':
+    switch (look(1)) {
+    case 'o':
+      First += 2;
+      return make<NameType>("operator^");
+    case 'O':
+      First += 2;
+      return make<NameType>("operator^=");
+    case 'q':
+      First += 2;
+      return make<NameType>("operator==");
+    }
+    return nullptr;
+  case 'g':
+    switch (look(1)) {
+    case 'e':
+      First += 2;
+      return make<NameType>("operator>=");
+    case 't':
+      First += 2;
+      return make<NameType>("operator>");
+    }
+    return nullptr;
+  case 'i':
+    if (look(1) == 'x') {
+      First += 2;
+      return make<NameType>("operator[]");
+    }
+    return nullptr;
+  case 'l':
+    switch (look(1)) {
+    case 'e':
+      First += 2;
+      return make<NameType>("operator<=");
+    //                   ::= li <source-name>  # operator ""
+    case 'i': {
+      First += 2;
+      Node *SN = getDerived().parseSourceName(State);
+      if (SN == nullptr)
+        return nullptr;
+      return make<LiteralOperator>(SN);
+    }
+    case 's':
+      First += 2;
+      return make<NameType>("operator<<");
+    case 'S':
+      First += 2;
+      return make<NameType>("operator<<=");
+    case 't':
+      First += 2;
+      return make<NameType>("operator<");
+    }
+    return nullptr;
+  case 'm':
+    switch (look(1)) {
+    case 'i':
+      First += 2;
+      return make<NameType>("operator-");
+    case 'I':
+      First += 2;
+      return make<NameType>("operator-=");
+    case 'l':
+      First += 2;
+      return make<NameType>("operator*");
+    case 'L':
+      First += 2;
+      return make<NameType>("operator*=");
+    case 'm':
+      First += 2;
+      return make<NameType>("operator--");
+    }
+    return nullptr;
+  case 'n':
+    switch (look(1)) {
+    case 'a':
+      First += 2;
+      return make<NameType>("operator new[]");
+    case 'e':
+      First += 2;
+      return make<NameType>("operator!=");
+    case 'g':
+      First += 2;
+      return make<NameType>("operator-");
+    case 't':
+      First += 2;
+      return make<NameType>("operator!");
+    case 'w':
+      First += 2;
+      return make<NameType>("operator new");
+    }
+    return nullptr;
+  case 'o':
+    switch (look(1)) {
+    case 'o':
+      First += 2;
+      return make<NameType>("operator||");
+    case 'r':
+      First += 2;
+      return make<NameType>("operator|");
+    case 'R':
+      First += 2;
+      return make<NameType>("operator|=");
+    }
+    return nullptr;
+  case 'p':
+    switch (look(1)) {
+    case 'm':
+      First += 2;
+      return make<NameType>("operator->*");
+    case 'l':
+      First += 2;
+      return make<NameType>("operator+");
+    case 'L':
+      First += 2;
+      return make<NameType>("operator+=");
+    case 'p':
+      First += 2;
+      return make<NameType>("operator++");
+    case 's':
+      First += 2;
+      return make<NameType>("operator+");
+    case 't':
+      First += 2;
+      return make<NameType>("operator->");
+    }
+    return nullptr;
+  case 'q':
+    if (look(1) == 'u') {
+      First += 2;
+      return make<NameType>("operator?");
+    }
+    return nullptr;
+  case 'r':
+    switch (look(1)) {
+    case 'm':
+      First += 2;
+      return make<NameType>("operator%");
+    case 'M':
+      First += 2;
+      return make<NameType>("operator%=");
+    case 's':
+      First += 2;
+      return make<NameType>("operator>>");
+    case 'S':
+      First += 2;
+      return make<NameType>("operator>>=");
+    }
+    return nullptr;
+  case 's':
+    if (look(1) == 's') {
+      First += 2;
+      return make<NameType>("operator<=>");
+    }
+    return nullptr;
+  // ::= v <digit> <source-name>        # vendor extended operator
+  case 'v':
+    if (std::isdigit(look(1))) {
+      First += 2;
+      Node *SN = getDerived().parseSourceName(State);
+      if (SN == nullptr)
+        return nullptr;
+      return make<ConversionOperatorType>(SN);
+    }
+    return nullptr;
+  }
+  return nullptr;
+}
+
+// <ctor-dtor-name> ::= C1  # complete object constructor
+//                  ::= C2  # base object constructor
+//                  ::= C3  # complete object allocating constructor
+//   extension      ::= C4  # gcc old-style "[unified]" constructor
+//   extension      ::= C5  # the COMDAT used for ctors
+//                  ::= D0  # deleting destructor
+//                  ::= D1  # complete object destructor
+//                  ::= D2  # base object destructor
+//   extension      ::= D4  # gcc old-style "[unified]" destructor
+//   extension      ::= D5  # the COMDAT used for dtors
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
+                                                          NameState *State) {
+  if (SoFar->getKind() == Node::KSpecialSubstitution) {
+    auto SSK = static_cast<SpecialSubstitution *>(SoFar)->SSK;
+    switch (SSK) {
+    case SpecialSubKind::string:
+    case SpecialSubKind::istream:
+    case SpecialSubKind::ostream:
+    case SpecialSubKind::iostream:
+      SoFar = make<ExpandedSpecialSubstitution>(SSK);
+      if (!SoFar)
+        return nullptr;
+      break;
+    default:
+      break;
+    }
+  }
+
+  if (consumeIf('C')) {
+    bool IsInherited = consumeIf('I');
+    if (look() != '1' && look() != '2' && look() != '3' && look() != '4' &&
+        look() != '5')
+      return nullptr;
+    int Variant = look() - '0';
+    ++First;
+    if (State) State->CtorDtorConversion = true;
+    if (IsInherited) {
+      if (getDerived().parseName(State) == nullptr)
+        return nullptr;
+    }
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/false, Variant);
+  }
+
+  if (look() == 'D' && (look(1) == '0' || look(1) == '1' || look(1) == '2' ||
+                        look(1) == '4' || look(1) == '5')) {
+    int Variant = look(1) - '0';
+    First += 2;
+    if (State) State->CtorDtorConversion = true;
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/true, Variant);
+  }
+
+  return nullptr;
+}
+
+// <nested-name> ::= N [<CV-Qualifiers>] [<ref-qualifier>] <prefix> <unqualified-name> E
+//               ::= N [<CV-Qualifiers>] [<ref-qualifier>] <template-prefix> <template-args> E
+//
+// <prefix> ::= <prefix> <unqualified-name>
+//          ::= <template-prefix> <template-args>
+//          ::= <template-param>
+//          ::= <decltype>
+//          ::= # empty
+//          ::= <substitution>
+//          ::= <prefix> <data-member-prefix>
+//  extension ::= L
+//
+// <data-member-prefix> := <member source-name> [<template-args>] M
+//
+// <template-prefix> ::= <prefix> <template unqualified-name>
+//                   ::= <template-param>
+//                   ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseNestedName(NameState *State) {
+  if (!consumeIf('N'))
+    return nullptr;
+
+  Qualifiers CVTmp = parseCVQualifiers();
+  if (State) State->CVQualifiers = CVTmp;
+
+  if (consumeIf('O')) {
+    if (State) State->ReferenceQualifier = FrefQualRValue;
+  } else if (consumeIf('R')) {
+    if (State) State->ReferenceQualifier = FrefQualLValue;
+  } else
+    if (State) State->ReferenceQualifier = FrefQualNone;
+
+  Node *SoFar = nullptr;
+  auto PushComponent = [&](Node *Comp) {
+    if (!Comp) return false;
+    if (SoFar) SoFar = make<NestedName>(SoFar, Comp);
+    else       SoFar = Comp;
+    if (State) State->EndsWithTemplateArgs = false;
+    return SoFar != nullptr;
+  };
+
+  if (consumeIf("St")) {
+    SoFar = make<NameType>("std");
+    if (!SoFar)
+      return nullptr;
+  }
+
+  while (!consumeIf('E')) {
+    consumeIf('L'); // extension
+
+    // <data-member-prefix> := <member source-name> [<template-args>] M
+    if (consumeIf('M')) {
+      if (SoFar == nullptr)
+        return nullptr;
+      continue;
+    }
+
+    //          ::= <template-param>
+    if (look() == 'T') {
+      if (!PushComponent(getDerived().parseTemplateParam()))
+        return nullptr;
+      Subs.push_back(SoFar);
+      continue;
+    }
+
+    //          ::= <template-prefix> <template-args>
+    if (look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs(State != nullptr);
+      if (TA == nullptr || SoFar == nullptr)
+        return nullptr;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+      if (!SoFar)
+        return nullptr;
+      if (State) State->EndsWithTemplateArgs = true;
+      Subs.push_back(SoFar);
+      continue;
+    }
+
+    //          ::= <decltype>
+    if (look() == 'D' && (look(1) == 't' || look(1) == 'T')) {
+      if (!PushComponent(getDerived().parseDecltype()))
+        return nullptr;
+      Subs.push_back(SoFar);
+      continue;
+    }
+
+    //          ::= <substitution>
+    if (look() == 'S' && look(1) != 't') {
+      Node *S = getDerived().parseSubstitution();
+      if (!PushComponent(S))
+        return nullptr;
+      if (SoFar != S)
+        Subs.push_back(S);
+      continue;
+    }
+
+    // Parse an <unqualified-name> thats actually a <ctor-dtor-name>.
+    if (look() == 'C' || (look() == 'D' && look(1) != 'C')) {
+      if (SoFar == nullptr)
+        return nullptr;
+      if (!PushComponent(getDerived().parseCtorDtorName(SoFar, State)))
+        return nullptr;
+      SoFar = getDerived().parseAbiTags(SoFar);
+      if (SoFar == nullptr)
+        return nullptr;
+      Subs.push_back(SoFar);
+      continue;
+    }
+
+    //          ::= <prefix> <unqualified-name>
+    if (!PushComponent(getDerived().parseUnqualifiedName(State)))
+      return nullptr;
+    Subs.push_back(SoFar);
+  }
+
+  if (SoFar == nullptr || Subs.empty())
+    return nullptr;
+
+  Subs.pop_back();
+  return SoFar;
+}
+
+// <simple-id> ::= <source-name> [ <template-args> ]
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSimpleId() {
+  Node *SN = getDerived().parseSourceName(/*NameState=*/nullptr);
+  if (SN == nullptr)
+    return nullptr;
+  if (look() == 'I') {
+    Node *TA = getDerived().parseTemplateArgs();
+    if (TA == nullptr)
+      return nullptr;
+    return make<NameWithTemplateArgs>(SN, TA);
+  }
+  return SN;
+}
+
+// <destructor-name> ::= <unresolved-type>  # e.g., ~T or ~decltype(f())
+//                   ::= <simple-id>        # e.g., ~A<2*N>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseDestructorName() {
+  Node *Result;
+  if (std::isdigit(look()))
+    Result = getDerived().parseSimpleId();
+  else
+    Result = getDerived().parseUnresolvedType();
+  if (Result == nullptr)
+    return nullptr;
+  return make<DtorName>(Result);
+}
+
+// <unresolved-type> ::= <template-param>
+//                   ::= <decltype>
+//                   ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedType() {
+  if (look() == 'T') {
+    Node *TP = getDerived().parseTemplateParam();
+    if (TP == nullptr)
+      return nullptr;
+    Subs.push_back(TP);
+    return TP;
+  }
+  if (look() == 'D') {
+    Node *DT = getDerived().parseDecltype();
+    if (DT == nullptr)
+      return nullptr;
+    Subs.push_back(DT);
+    return DT;
+  }
+  return getDerived().parseSubstitution();
+}
+
+// <base-unresolved-name> ::= <simple-id>                                # unresolved name
+//          extension     ::= <operator-name>                            # unresolved operator-function-id
+//          extension     ::= <operator-name> <template-args>            # unresolved operator template-id
+//                        ::= on <operator-name>                         # unresolved operator-function-id
+//                        ::= on <operator-name> <template-args>         # unresolved operator template-id
+//                        ::= dn <destructor-name>                       # destructor or pseudo-destructor;
+//                                                                         # e.g. ~X or ~X<N-1>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBaseUnresolvedName() {
+  if (std::isdigit(look()))
+    return getDerived().parseSimpleId();
+
+  if (consumeIf("dn"))
+    return getDerived().parseDestructorName();
+
+  consumeIf("on");
+
+  Node *Oper = getDerived().parseOperatorName(/*NameState=*/nullptr);
+  if (Oper == nullptr)
+    return nullptr;
+  if (look() == 'I') {
+    Node *TA = getDerived().parseTemplateArgs();
+    if (TA == nullptr)
+      return nullptr;
+    return make<NameWithTemplateArgs>(Oper, TA);
+  }
+  return Oper;
+}
+
+// <unresolved-name>
+//  extension        ::= srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
+//                   ::= [gs] <base-unresolved-name>                     # x or (with "gs") ::x
+//                   ::= [gs] sr <unresolved-qualifier-level>+ E <base-unresolved-name>
+//                                                                       # A::x, N::y, A<T>::z; "gs" means leading "::"
+//                   ::= sr <unresolved-type> <base-unresolved-name>     # T::x / decltype(p)::x
+//  extension        ::= sr <unresolved-type> <template-args> <base-unresolved-name>
+//                                                                       # T::N::x /decltype(p)::N::x
+//  (ignored)        ::= srN <unresolved-type>  <unresolved-qualifier-level>+ E <base-unresolved-name>
+//
+// <unresolved-qualifier-level> ::= <simple-id>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName() {
+  Node *SoFar = nullptr;
+
+  // srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
+  // srN <unresolved-type>                   <unresolved-qualifier-level>+ E <base-unresolved-name>
+  if (consumeIf("srN")) {
+    SoFar = getDerived().parseUnresolvedType();
+    if (SoFar == nullptr)
+      return nullptr;
+
+    if (look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+      if (!SoFar)
+        return nullptr;
+    }
+
+    while (!consumeIf('E')) {
+      Node *Qual = getDerived().parseSimpleId();
+      if (Qual == nullptr)
+        return nullptr;
+      SoFar = make<QualifiedName>(SoFar, Qual);
+      if (!SoFar)
+        return nullptr;
+    }
+
+    Node *Base = getDerived().parseBaseUnresolvedName();
+    if (Base == nullptr)
+      return nullptr;
+    return make<QualifiedName>(SoFar, Base);
+  }
+
+  bool Global = consumeIf("gs");
+
+  // [gs] <base-unresolved-name>                     # x or (with "gs") ::x
+  if (!consumeIf("sr")) {
+    SoFar = getDerived().parseBaseUnresolvedName();
+    if (SoFar == nullptr)
+      return nullptr;
+    if (Global)
+      SoFar = make<GlobalQualifiedName>(SoFar);
+    return SoFar;
+  }
+
+  // [gs] sr <unresolved-qualifier-level>+ E   <base-unresolved-name>
+  if (std::isdigit(look())) {
+    do {
+      Node *Qual = getDerived().parseSimpleId();
+      if (Qual == nullptr)
+        return nullptr;
+      if (SoFar)
+        SoFar = make<QualifiedName>(SoFar, Qual);
+      else if (Global)
+        SoFar = make<GlobalQualifiedName>(Qual);
+      else
+        SoFar = Qual;
+      if (!SoFar)
+        return nullptr;
+    } while (!consumeIf('E'));
+  }
+  //      sr <unresolved-type>                 <base-unresolved-name>
+  //      sr <unresolved-type> <template-args> <base-unresolved-name>
+  else {
+    SoFar = getDerived().parseUnresolvedType();
+    if (SoFar == nullptr)
+      return nullptr;
+
+    if (look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+      if (!SoFar)
+        return nullptr;
+    }
+  }
+
+  assert(SoFar != nullptr);
+
+  Node *Base = getDerived().parseBaseUnresolvedName();
+  if (Base == nullptr)
+    return nullptr;
+  return make<QualifiedName>(SoFar, Base);
+}
+
+// <abi-tags> ::= <abi-tag> [<abi-tags>]
+// <abi-tag> ::= B <source-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseAbiTags(Node *N) {
+  while (consumeIf('B')) {
+    StringView SN = parseBareSourceName();
+    if (SN.empty())
+      return nullptr;
+    N = make<AbiTagAttr>(N, SN);
+    if (!N)
+      return nullptr;
+  }
+  return N;
+}
+
+// <number> ::= [n] <non-negative decimal integer>
+template <typename Alloc, typename Derived>
+StringView
+AbstractManglingParser<Alloc, Derived>::parseNumber(bool AllowNegative) {
+  const char *Tmp = First;
+  if (AllowNegative)
+    consumeIf('n');
+  if (numLeft() == 0 || !std::isdigit(*First))
+    return StringView();
+  while (numLeft() != 0 && std::isdigit(*First))
+    ++First;
+  return StringView(Tmp, First);
+}
+
+// <positive length number> ::= [0-9]*
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parsePositiveInteger(size_t *Out) {
+  *Out = 0;
+  if (look() < '0' || look() > '9')
+    return true;
+  while (look() >= '0' && look() <= '9') {
+    *Out *= 10;
+    *Out += static_cast<size_t>(consume() - '0');
+  }
+  return false;
+}
+
+template <typename Alloc, typename Derived>
+StringView AbstractManglingParser<Alloc, Derived>::parseBareSourceName() {
+  size_t Int = 0;
+  if (parsePositiveInteger(&Int) || numLeft() < Int)
+    return StringView();
+  StringView R(First, First + Int);
+  First += Int;
+  return R;
+}
+
+// <function-type> ::= [<CV-qualifiers>] [<exception-spec>] [Dx] F [Y] <bare-function-type> [<ref-qualifier>] E
+//
+// <exception-spec> ::= Do                # non-throwing exception-specification (e.g., noexcept, throw())
+//                  ::= DO <expression> E # computed (instantiation-dependent) noexcept
+//                  ::= Dw <type>+ E      # dynamic exception specification with instantiation-dependent types
+//
+// <ref-qualifier> ::= R                   # & ref-qualifier
+// <ref-qualifier> ::= O                   # && ref-qualifier
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFunctionType() {
+  Qualifiers CVQuals = parseCVQualifiers();
+
+  Node *ExceptionSpec = nullptr;
+  if (consumeIf("Do")) {
+    ExceptionSpec = make<NameType>("noexcept");
+    if (!ExceptionSpec)
+      return nullptr;
+  } else if (consumeIf("DO")) {
+    Node *E = getDerived().parseExpr();
+    if (E == nullptr || !consumeIf('E'))
+      return nullptr;
+    ExceptionSpec = make<NoexceptSpec>(E);
+    if (!ExceptionSpec)
+      return nullptr;
+  } else if (consumeIf("Dw")) {
+    size_t SpecsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *T = getDerived().parseType();
+      if (T == nullptr)
+        return nullptr;
+      Names.push_back(T);
+    }
+    ExceptionSpec =
+      make<DynamicExceptionSpec>(popTrailingNodeArray(SpecsBegin));
+    if (!ExceptionSpec)
+      return nullptr;
+  }
+
+  consumeIf("Dx"); // transaction safe
+
+  if (!consumeIf('F'))
+    return nullptr;
+  consumeIf('Y'); // extern "C"
+  Node *ReturnType = getDerived().parseType();
+  if (ReturnType == nullptr)
+    return nullptr;
+
+  FunctionRefQual ReferenceQualifier = FrefQualNone;
+  size_t ParamsBegin = Names.size();
+  while (true) {
+    if (consumeIf('E'))
+      break;
+    if (consumeIf('v'))
+      continue;
+    if (consumeIf("RE")) {
+      ReferenceQualifier = FrefQualLValue;
+      break;
+    }
+    if (consumeIf("OE")) {
+      ReferenceQualifier = FrefQualRValue;
+      break;
+    }
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    Names.push_back(T);
+  }
+
+  NodeArray Params = popTrailingNodeArray(ParamsBegin);
+  return make<FunctionType>(ReturnType, Params, CVQuals,
+                            ReferenceQualifier, ExceptionSpec);
+}
+
+// extension:
+// <vector-type>           ::= Dv <positive dimension number> _ <extended element type>
+//                         ::= Dv [<dimension expression>] _ <element type>
+// <extended element type> ::= <element type>
+//                         ::= p # AltiVec vector pixel
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseVectorType() {
+  if (!consumeIf("Dv"))
+    return nullptr;
+  if (look() >= '1' && look() <= '9') {
+    Node *DimensionNumber = make<NameType>(parseNumber());
+    if (!DimensionNumber)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    if (consumeIf('p'))
+      return make<PixelVectorType>(DimensionNumber);
+    Node *ElemType = getDerived().parseType();
+    if (ElemType == nullptr)
+      return nullptr;
+    return make<VectorType>(ElemType, DimensionNumber);
+  }
+
+  if (!consumeIf('_')) {
+    Node *DimExpr = getDerived().parseExpr();
+    if (!DimExpr)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    Node *ElemType = getDerived().parseType();
+    if (!ElemType)
+      return nullptr;
+    return make<VectorType>(ElemType, DimExpr);
+  }
+  Node *ElemType = getDerived().parseType();
+  if (!ElemType)
+    return nullptr;
+  return make<VectorType>(ElemType, /*Dimension=*/nullptr);
+}
+
+// <decltype>  ::= Dt <expression> E  # decltype of an id-expression or class member access (C++0x)
+//             ::= DT <expression> E  # decltype of an expression (C++0x)
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseDecltype() {
+  if (!consumeIf('D'))
+    return nullptr;
+  if (!consumeIf('t') && !consumeIf('T'))
+    return nullptr;
+  Node *E = getDerived().parseExpr();
+  if (E == nullptr)
+    return nullptr;
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<EnclosingExpr>("decltype(", E, ")");
+}
+
+// <array-type> ::= A <positive dimension number> _ <element type>
+//              ::= A [<dimension expression>] _ <element type>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseArrayType() {
+  if (!consumeIf('A'))
+    return nullptr;
+
+  Node *Dimension = nullptr;
+
+  if (std::isdigit(look())) {
+    Dimension = make<NameType>(parseNumber());
+    if (!Dimension)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+  } else if (!consumeIf('_')) {
+    Node *DimExpr = getDerived().parseExpr();
+    if (DimExpr == nullptr)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    Dimension = DimExpr;
+  }
+
+  Node *Ty = getDerived().parseType();
+  if (Ty == nullptr)
+    return nullptr;
+  return make<ArrayType>(Ty, Dimension);
+}
+
+// <pointer-to-member-type> ::= M <class type> <member type>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parsePointerToMemberType() {
+  if (!consumeIf('M'))
+    return nullptr;
+  Node *ClassType = getDerived().parseType();
+  if (ClassType == nullptr)
+    return nullptr;
+  Node *MemberType = getDerived().parseType();
+  if (MemberType == nullptr)
+    return nullptr;
+  return make<PointerToMemberType>(ClassType, MemberType);
+}
+
+// <class-enum-type> ::= <name>     # non-dependent type name, dependent type name, or dependent typename-specifier
+//                   ::= Ts <name>  # dependent elaborated type specifier using 'struct' or 'class'
+//                   ::= Tu <name>  # dependent elaborated type specifier using 'union'
+//                   ::= Te <name>  # dependent elaborated type specifier using 'enum'
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseClassEnumType() {
+  StringView ElabSpef;
+  if (consumeIf("Ts"))
+    ElabSpef = "struct";
+  else if (consumeIf("Tu"))
+    ElabSpef = "union";
+  else if (consumeIf("Te"))
+    ElabSpef = "enum";
+
+  Node *Name = getDerived().parseName();
+  if (Name == nullptr)
+    return nullptr;
+
+  if (!ElabSpef.empty())
+    return make<ElaboratedTypeSpefType>(ElabSpef, Name);
+
+  return Name;
+}
+
+// <qualified-type>     ::= <qualifiers> <type>
+// <qualifiers> ::= <extended-qualifier>* <CV-qualifiers>
+// <extended-qualifier> ::= U <source-name> [<template-args>] # vendor extended type qualifier
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseQualifiedType() {
+  if (consumeIf('U')) {
+    StringView Qual = parseBareSourceName();
+    if (Qual.empty())
+      return nullptr;
+
+    // FIXME parse the optional <template-args> here!
+
+    // extension            ::= U <objc-name> <objc-type>  # objc-type<identifier>
+    if (Qual.startsWith("objcproto")) {
+      StringView ProtoSourceName = Qual.dropFront(std::strlen("objcproto"));
+      StringView Proto;
+      {
+        SwapAndRestore<const char *> SaveFirst(First, ProtoSourceName.begin()),
+                                     SaveLast(Last, ProtoSourceName.end());
+        Proto = parseBareSourceName();
+      }
+      if (Proto.empty())
+        return nullptr;
+      Node *Child = getDerived().parseQualifiedType();
+      if (Child == nullptr)
+        return nullptr;
+      return make<ObjCProtoName>(Child, Proto);
+    }
+
+    Node *Child = getDerived().parseQualifiedType();
+    if (Child == nullptr)
+      return nullptr;
+    return make<VendorExtQualType>(Child, Qual);
+  }
+
+  Qualifiers Quals = parseCVQualifiers();
+  Node *Ty = getDerived().parseType();
+  if (Ty == nullptr)
+    return nullptr;
+  if (Quals != QualNone)
+    Ty = make<QualType>(Ty, Quals);
+  return Ty;
+}
+
+// <type>      ::= <builtin-type>
+//             ::= <qualified-type>
+//             ::= <function-type>
+//             ::= <class-enum-type>
+//             ::= <array-type>
+//             ::= <pointer-to-member-type>
+//             ::= <template-param>
+//             ::= <template-template-param> <template-args>
+//             ::= <decltype>
+//             ::= P <type>        # pointer
+//             ::= R <type>        # l-value reference
+//             ::= O <type>        # r-value reference (C++11)
+//             ::= C <type>        # complex pair (C99)
+//             ::= G <type>        # imaginary (C99)
+//             ::= <substitution>  # See Compression below
+// extension   ::= U <objc-name> <objc-type>  # objc-type<identifier>
+// extension   ::= <vector-type> # <vector-type> starts with Dv
+//
+// <objc-name> ::= <k0 number> objcproto <k1 number> <identifier>  # k0 = 9 + <number of digits in k1> + k1
+// <objc-type> ::= <source-name>  # PU<11+>objcproto 11objc_object<source-name> 11objc_object -> id<source-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseType() {
+  Node *Result = nullptr;
+
+  switch (look()) {
+  //             ::= <qualified-type>
+  case 'r':
+  case 'V':
+  case 'K': {
+    unsigned AfterQuals = 0;
+    if (look(AfterQuals) == 'r') ++AfterQuals;
+    if (look(AfterQuals) == 'V') ++AfterQuals;
+    if (look(AfterQuals) == 'K') ++AfterQuals;
+
+    if (look(AfterQuals) == 'F' ||
+        (look(AfterQuals) == 'D' &&
+         (look(AfterQuals + 1) == 'o' || look(AfterQuals + 1) == 'O' ||
+          look(AfterQuals + 1) == 'w' || look(AfterQuals + 1) == 'x'))) {
+      Result = getDerived().parseFunctionType();
+      break;
+    }
+    DEMANGLE_FALLTHROUGH;
+  }
+  case 'U': {
+    Result = getDerived().parseQualifiedType();
+    break;
+  }
+  // <builtin-type> ::= v    # void
+  case 'v':
+    ++First;
+    return make<NameType>("void");
+  //                ::= w    # wchar_t
+  case 'w':
+    ++First;
+    return make<NameType>("wchar_t");
+  //                ::= b    # bool
+  case 'b':
+    ++First;
+    return make<NameType>("bool");
+  //                ::= c    # char
+  case 'c':
+    ++First;
+    return make<NameType>("char");
+  //                ::= a    # signed char
+  case 'a':
+    ++First;
+    return make<NameType>("signed char");
+  //                ::= h    # unsigned char
+  case 'h':
+    ++First;
+    return make<NameType>("unsigned char");
+  //                ::= s    # short
+  case 's':
+    ++First;
+    return make<NameType>("short");
+  //                ::= t    # unsigned short
+  case 't':
+    ++First;
+    return make<NameType>("unsigned short");
+  //                ::= i    # int
+  case 'i':
+    ++First;
+    return make<NameType>("int");
+  //                ::= j    # unsigned int
+  case 'j':
+    ++First;
+    return make<NameType>("unsigned int");
+  //                ::= l    # long
+  case 'l':
+    ++First;
+    return make<NameType>("long");
+  //                ::= m    # unsigned long
+  case 'm':
+    ++First;
+    return make<NameType>("unsigned long");
+  //                ::= x    # long long, __int64
+  case 'x':
+    ++First;
+    return make<NameType>("long long");
+  //                ::= y    # unsigned long long, __int64
+  case 'y':
+    ++First;
+    return make<NameType>("unsigned long long");
+  //                ::= n    # __int128
+  case 'n':
+    ++First;
+    return make<NameType>("__int128");
+  //                ::= o    # unsigned __int128
+  case 'o':
+    ++First;
+    return make<NameType>("unsigned __int128");
+  //                ::= f    # float
+  case 'f':
+    ++First;
+    return make<NameType>("float");
+  //                ::= d    # double
+  case 'd':
+    ++First;
+    return make<NameType>("double");
+  //                ::= e    # long double, __float80
+  case 'e':
+    ++First;
+    return make<NameType>("long double");
+  //                ::= g    # __float128
+  case 'g':
+    ++First;
+    return make<NameType>("__float128");
+  //                ::= z    # ellipsis
+  case 'z':
+    ++First;
+    return make<NameType>("...");
+
+  // <builtin-type> ::= u <source-name>    # vendor extended type
+  case 'u': {
+    ++First;
+    StringView Res = parseBareSourceName();
+    if (Res.empty())
+      return nullptr;
+    // Typically, <builtin-type>s are not considered substitution candidates,
+    // but the exception to that exception is vendor extended types (Itanium C++
+    // ABI 5.9.1).
+    Result = make<NameType>(Res);
+    break;
+  }
+  case 'D':
+    switch (look(1)) {
+    //                ::= Dd   # IEEE 754r decimal floating point (64 bits)
+    case 'd':
+      First += 2;
+      return make<NameType>("decimal64");
+    //                ::= De   # IEEE 754r decimal floating point (128 bits)
+    case 'e':
+      First += 2;
+      return make<NameType>("decimal128");
+    //                ::= Df   # IEEE 754r decimal floating point (32 bits)
+    case 'f':
+      First += 2;
+      return make<NameType>("decimal32");
+    //                ::= Dh   # IEEE 754r half-precision floating point (16 bits)
+    case 'h':
+      First += 2;
+      return make<NameType>("decimal16");
+    //                ::= Di   # char32_t
+    case 'i':
+      First += 2;
+      return make<NameType>("char32_t");
+    //                ::= Ds   # char16_t
+    case 's':
+      First += 2;
+      return make<NameType>("char16_t");
+    //                ::= Du   # char8_t (C++2a, not yet in the Itanium spec)
+    case 'u':
+      First += 2;
+      return make<NameType>("char8_t");
+    //                ::= Da   # auto (in dependent new-expressions)
+    case 'a':
+      First += 2;
+      return make<NameType>("auto");
+    //                ::= Dc   # decltype(auto)
+    case 'c':
+      First += 2;
+      return make<NameType>("decltype(auto)");
+    //                ::= Dn   # std::nullptr_t (i.e., decltype(nullptr))
+    case 'n':
+      First += 2;
+      return make<NameType>("std::nullptr_t");
+
+    //             ::= <decltype>
+    case 't':
+    case 'T': {
+      Result = getDerived().parseDecltype();
+      break;
+    }
+    // extension   ::= <vector-type> # <vector-type> starts with Dv
+    case 'v': {
+      Result = getDerived().parseVectorType();
+      break;
+    }
+    //           ::= Dp <type>       # pack expansion (C++0x)
+    case 'p': {
+      First += 2;
+      Node *Child = getDerived().parseType();
+      if (!Child)
+        return nullptr;
+      Result = make<ParameterPackExpansion>(Child);
+      break;
+    }
+    // Exception specifier on a function type.
+    case 'o':
+    case 'O':
+    case 'w':
+    // Transaction safe function type.
+    case 'x':
+      Result = getDerived().parseFunctionType();
+      break;
+    }
+    break;
+  //             ::= <function-type>
+  case 'F': {
+    Result = getDerived().parseFunctionType();
+    break;
+  }
+  //             ::= <array-type>
+  case 'A': {
+    Result = getDerived().parseArrayType();
+    break;
+  }
+  //             ::= <pointer-to-member-type>
+  case 'M': {
+    Result = getDerived().parsePointerToMemberType();
+    break;
+  }
+  //             ::= <template-param>
+  case 'T': {
+    // This could be an elaborate type specifier on a <class-enum-type>.
+    if (look(1) == 's' || look(1) == 'u' || look(1) == 'e') {
+      Result = getDerived().parseClassEnumType();
+      break;
+    }
+
+    Result = getDerived().parseTemplateParam();
+    if (Result == nullptr)
+      return nullptr;
+
+    // Result could be either of:
+    //   <type>        ::= <template-param>
+    //   <type>        ::= <template-template-param> <template-args>
+    //
+    //   <template-template-param> ::= <template-param>
+    //                             ::= <substitution>
+    //
+    // If this is followed by some <template-args>, and we're permitted to
+    // parse them, take the second production.
+
+    if (TryToParseTemplateArgs && look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      Result = make<NameWithTemplateArgs>(Result, TA);
+    }
+    break;
+  }
+  //             ::= P <type>        # pointer
+  case 'P': {
+    ++First;
+    Node *Ptr = getDerived().parseType();
+    if (Ptr == nullptr)
+      return nullptr;
+    Result = make<PointerType>(Ptr);
+    break;
+  }
+  //             ::= R <type>        # l-value reference
+  case 'R': {
+    ++First;
+    Node *Ref = getDerived().parseType();
+    if (Ref == nullptr)
+      return nullptr;
+    Result = make<ReferenceType>(Ref, ReferenceKind::LValue);
+    break;
+  }
+  //             ::= O <type>        # r-value reference (C++11)
+  case 'O': {
+    ++First;
+    Node *Ref = getDerived().parseType();
+    if (Ref == nullptr)
+      return nullptr;
+    Result = make<ReferenceType>(Ref, ReferenceKind::RValue);
+    break;
+  }
+  //             ::= C <type>        # complex pair (C99)
+  case 'C': {
+    ++First;
+    Node *P = getDerived().parseType();
+    if (P == nullptr)
+      return nullptr;
+    Result = make<PostfixQualifiedType>(P, " complex");
+    break;
+  }
+  //             ::= G <type>        # imaginary (C99)
+  case 'G': {
+    ++First;
+    Node *P = getDerived().parseType();
+    if (P == nullptr)
+      return P;
+    Result = make<PostfixQualifiedType>(P, " imaginary");
+    break;
+  }
+  //             ::= <substitution>  # See Compression below
+  case 'S': {
+    if (look(1) && look(1) != 't') {
+      Node *Sub = getDerived().parseSubstitution();
+      if (Sub == nullptr)
+        return nullptr;
+
+      // Sub could be either of:
+      //   <type>        ::= <substitution>
+      //   <type>        ::= <template-template-param> <template-args>
+      //
+      //   <template-template-param> ::= <template-param>
+      //                             ::= <substitution>
+      //
+      // If this is followed by some <template-args>, and we're permitted to
+      // parse them, take the second production.
+
+      if (TryToParseTemplateArgs && look() == 'I') {
+        Node *TA = getDerived().parseTemplateArgs();
+        if (TA == nullptr)
+          return nullptr;
+        Result = make<NameWithTemplateArgs>(Sub, TA);
+        break;
+      }
+
+      // If all we parsed was a substitution, don't re-insert into the
+      // substitution table.
+      return Sub;
+    }
+    DEMANGLE_FALLTHROUGH;
+  }
+  //        ::= <class-enum-type>
+  default: {
+    Result = getDerived().parseClassEnumType();
+    break;
+  }
+  }
+
+  // If we parsed a type, insert it into the substitution table. Note that all
+  // <builtin-type>s and <substitution>s have already bailed out, because they
+  // don't get substitutions.
+  if (Result != nullptr)
+    Subs.push_back(Result);
+  return Result;
+}
+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parsePrefixExpr(StringView Kind) {
+  Node *E = getDerived().parseExpr();
+  if (E == nullptr)
+    return nullptr;
+  return make<PrefixExpr>(Kind, E);
+}
+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBinaryExpr(StringView Kind) {
+  Node *LHS = getDerived().parseExpr();
+  if (LHS == nullptr)
+    return nullptr;
+  Node *RHS = getDerived().parseExpr();
+  if (RHS == nullptr)
+    return nullptr;
+  return make<BinaryExpr>(LHS, Kind, RHS);
+}
+
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseIntegerLiteral(StringView Lit) {
+  StringView Tmp = parseNumber(true);
+  if (!Tmp.empty() && consumeIf('E'))
+    return make<IntegerLiteral>(Lit, Tmp);
+  return nullptr;
+}
+
+// <CV-Qualifiers> ::= [r] [V] [K]
+template <typename Alloc, typename Derived>
+Qualifiers AbstractManglingParser<Alloc, Derived>::parseCVQualifiers() {
+  Qualifiers CVR = QualNone;
+  if (consumeIf('r'))
+    CVR |= QualRestrict;
+  if (consumeIf('V'))
+    CVR |= QualVolatile;
+  if (consumeIf('K'))
+    CVR |= QualConst;
+  return CVR;
+}
+
+// <function-param> ::= fp <top-level CV-Qualifiers> _                                     # L == 0, first parameter
+//                  ::= fp <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L == 0, second and later parameters
+//                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> _         # L > 0, first parameter
+//                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L > 0, second and later parameters
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFunctionParam() {
+  if (consumeIf("fp")) {
+    parseCVQualifiers();
+    StringView Num = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<FunctionParam>(Num);
+  }
+  if (consumeIf("fL")) {
+    if (parseNumber().empty())
+      return nullptr;
+    if (!consumeIf('p'))
+      return nullptr;
+    parseCVQualifiers();
+    StringView Num = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<FunctionParam>(Num);
+  }
+  return nullptr;
+}
+
+// [gs] nw <expression>* _ <type> E                     # new (expr-list) type
+// [gs] nw <expression>* _ <type> <initializer>         # new (expr-list) type (init)
+// [gs] na <expression>* _ <type> E                     # new[] (expr-list) type
+// [gs] na <expression>* _ <type> <initializer>         # new[] (expr-list) type (init)
+// <initializer> ::= pi <expression>* E                 # parenthesized initialization
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseNewExpr() {
+  bool Global = consumeIf("gs");
+  bool IsArray = look(1) == 'a';
+  if (!consumeIf("nw") && !consumeIf("na"))
+    return nullptr;
+  size_t Exprs = Names.size();
+  while (!consumeIf('_')) {
+    Node *Ex = getDerived().parseExpr();
+    if (Ex == nullptr)
+      return nullptr;
+    Names.push_back(Ex);
+  }
+  NodeArray ExprList = popTrailingNodeArray(Exprs);
+  Node *Ty = getDerived().parseType();
+  if (Ty == nullptr)
+    return Ty;
+  if (consumeIf("pi")) {
+    size_t InitsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *Init = getDerived().parseExpr();
+      if (Init == nullptr)
+        return Init;
+      Names.push_back(Init);
+    }
+    NodeArray Inits = popTrailingNodeArray(InitsBegin);
+    return make<NewExpr>(ExprList, Ty, Inits, Global, IsArray);
+  } else if (!consumeIf('E'))
+    return nullptr;
+  return make<NewExpr>(ExprList, Ty, NodeArray(), Global, IsArray);
+}
+
+// cv <type> <expression>                               # conversion with one argument
+// cv <type> _ <expression>* E                          # conversion with a different number of arguments
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseConversionExpr() {
+  if (!consumeIf("cv"))
+    return nullptr;
+  Node *Ty;
+  {
+    SwapAndRestore<bool> SaveTemp(TryToParseTemplateArgs, false);
+    Ty = getDerived().parseType();
+  }
+
+  if (Ty == nullptr)
+    return nullptr;
+
+  if (consumeIf('_')) {
+    size_t ExprsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseExpr();
+      if (E == nullptr)
+        return E;
+      Names.push_back(E);
+    }
+    NodeArray Exprs = popTrailingNodeArray(ExprsBegin);
+    return make<ConversionExpr>(Ty, Exprs);
+  }
+
+  Node *E[1] = {getDerived().parseExpr()};
+  if (E[0] == nullptr)
+    return nullptr;
+  return make<ConversionExpr>(Ty, makeNodeArray(E, E + 1));
+}
+
+// <expr-primary> ::= L <type> <value number> E                          # integer literal
+//                ::= L <type> <value float> E                           # floating literal
+//                ::= L <string type> E                                  # string literal
+//                ::= L <nullptr type> E                                 # nullptr literal (i.e., "LDnE")
+//                ::= L <lambda type> E                                  # lambda expression
+// FIXME:         ::= L <type> <real-part float> _ <imag-part float> E   # complex floating point literal (C 2000)
+//                ::= L <mangled-name> E                                 # external name
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseExprPrimary() {
+  if (!consumeIf('L'))
+    return nullptr;
+  switch (look()) {
+  case 'w':
+    ++First;
+    return getDerived().parseIntegerLiteral("wchar_t");
+  case 'b':
+    if (consumeIf("b0E"))
+      return make<BoolExpr>(0);
+    if (consumeIf("b1E"))
+      return make<BoolExpr>(1);
+    return nullptr;
+  case 'c':
+    ++First;
+    return getDerived().parseIntegerLiteral("char");
+  case 'a':
+    ++First;
+    return getDerived().parseIntegerLiteral("signed char");
+  case 'h':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned char");
+  case 's':
+    ++First;
+    return getDerived().parseIntegerLiteral("short");
+  case 't':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned short");
+  case 'i':
+    ++First;
+    return getDerived().parseIntegerLiteral("");
+  case 'j':
+    ++First;
+    return getDerived().parseIntegerLiteral("u");
+  case 'l':
+    ++First;
+    return getDerived().parseIntegerLiteral("l");
+  case 'm':
+    ++First;
+    return getDerived().parseIntegerLiteral("ul");
+  case 'x':
+    ++First;
+    return getDerived().parseIntegerLiteral("ll");
+  case 'y':
+    ++First;
+    return getDerived().parseIntegerLiteral("ull");
+  case 'n':
+    ++First;
+    return getDerived().parseIntegerLiteral("__int128");
+  case 'o':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned __int128");
+  case 'f':
+    ++First;
+    return getDerived().template parseFloatingLiteral<float>();
+  case 'd':
+    ++First;
+    return getDerived().template parseFloatingLiteral<double>();
+  case 'e':
+    ++First;
+    return getDerived().template parseFloatingLiteral<long double>();
+  case '_':
+    if (consumeIf("_Z")) {
+      Node *R = getDerived().parseEncoding();
+      if (R != nullptr && consumeIf('E'))
+        return R;
+    }
+    return nullptr;
+  case 'A': {
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    // FIXME: We need to include the string contents in the mangling.
+    if (consumeIf('E'))
+      return make<StringLiteral>(T);
+    return nullptr;
+  }
+  case 'D':
+    if (consumeIf("DnE"))
+      return make<NameType>("nullptr");
+    return nullptr;
+  case 'T':
+    // Invalid mangled name per
+    //   http://sourcerytools.com/pipermail/cxx-abi-dev/2011-August/002422.html
+    return nullptr;
+  case 'U': {
+    // FIXME: Should we support LUb... for block literals?
+    if (look(1) != 'l')
+      return nullptr;
+    Node *T = parseUnnamedTypeName(nullptr);
+    if (!T || !consumeIf('E'))
+      return nullptr;
+    return make<LambdaExpr>(T);
+  }
+  default: {
+    // might be named type
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    StringView N = parseNumber();
+    if (N.empty())
+      return nullptr;
+    if (!consumeIf('E'))
+      return nullptr;
+    return make<IntegerCastExpr>(T, N);
+  }
+  }
+}
+
+// <braced-expression> ::= <expression>
+//                     ::= di <field source-name> <braced-expression>    # .name = expr
+//                     ::= dx <index expression> <braced-expression>     # [expr] = expr
+//                     ::= dX <range begin expression> <range end expression> <braced-expression>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBracedExpr() {
+  if (look() == 'd') {
+    switch (look(1)) {
+    case 'i': {
+      First += 2;
+      Node *Field = getDerived().parseSourceName(/*NameState=*/nullptr);
+      if (Field == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedExpr>(Field, Init, /*isArray=*/false);
+    }
+    case 'x': {
+      First += 2;
+      Node *Index = getDerived().parseExpr();
+      if (Index == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedExpr>(Index, Init, /*isArray=*/true);
+    }
+    case 'X': {
+      First += 2;
+      Node *RangeBegin = getDerived().parseExpr();
+      if (RangeBegin == nullptr)
+        return nullptr;
+      Node *RangeEnd = getDerived().parseExpr();
+      if (RangeEnd == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedRangeExpr>(RangeBegin, RangeEnd, Init);
+    }
+    }
+  }
+  return getDerived().parseExpr();
+}
+
+// (not yet in the spec)
+// <fold-expr> ::= fL <binary-operator-name> <expression> <expression>
+//             ::= fR <binary-operator-name> <expression> <expression>
+//             ::= fl <binary-operator-name> <expression>
+//             ::= fr <binary-operator-name> <expression>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFoldExpr() {
+  if (!consumeIf('f'))
+    return nullptr;
+
+  char FoldKind = look();
+  bool IsLeftFold, HasInitializer;
+  HasInitializer = FoldKind == 'L' || FoldKind == 'R';
+  if (FoldKind == 'l' || FoldKind == 'L')
+    IsLeftFold = true;
+  else if (FoldKind == 'r' || FoldKind == 'R')
+    IsLeftFold = false;
+  else
+    return nullptr;
+  ++First;
+
+  // FIXME: This map is duplicated in parseOperatorName and parseExpr.
+  StringView OperatorName;
+  if      (consumeIf("aa")) OperatorName = "&&";
+  else if (consumeIf("an")) OperatorName = "&";
+  else if (consumeIf("aN")) OperatorName = "&=";
+  else if (consumeIf("aS")) OperatorName = "=";
+  else if (consumeIf("cm")) OperatorName = ",";
+  else if (consumeIf("ds")) OperatorName = ".*";
+  else if (consumeIf("dv")) OperatorName = "/";
+  else if (consumeIf("dV")) OperatorName = "/=";
+  else if (consumeIf("eo")) OperatorName = "^";
+  else if (consumeIf("eO")) OperatorName = "^=";
+  else if (consumeIf("eq")) OperatorName = "==";
+  else if (consumeIf("ge")) OperatorName = ">=";
+  else if (consumeIf("gt")) OperatorName = ">";
+  else if (consumeIf("le")) OperatorName = "<=";
+  else if (consumeIf("ls")) OperatorName = "<<";
+  else if (consumeIf("lS")) OperatorName = "<<=";
+  else if (consumeIf("lt")) OperatorName = "<";
+  else if (consumeIf("mi")) OperatorName = "-";
+  else if (consumeIf("mI")) OperatorName = "-=";
+  else if (consumeIf("ml")) OperatorName = "*";
+  else if (consumeIf("mL")) OperatorName = "*=";
+  else if (consumeIf("ne")) OperatorName = "!=";
+  else if (consumeIf("oo")) OperatorName = "||";
+  else if (consumeIf("or")) OperatorName = "|";
+  else if (consumeIf("oR")) OperatorName = "|=";
+  else if (consumeIf("pl")) OperatorName = "+";
+  else if (consumeIf("pL")) OperatorName = "+=";
+  else if (consumeIf("rm")) OperatorName = "%";
+  else if (consumeIf("rM")) OperatorName = "%=";
+  else if (consumeIf("rs")) OperatorName = ">>";
+  else if (consumeIf("rS")) OperatorName = ">>=";
+  else return nullptr;
+
+  Node *Pack = getDerived().parseExpr(), *Init = nullptr;
+  if (Pack == nullptr)
+    return nullptr;
+  if (HasInitializer) {
+    Init = getDerived().parseExpr();
+    if (Init == nullptr)
+      return nullptr;
+  }
+
+  if (IsLeftFold && Init)
+    std::swap(Pack, Init);
+
+  return make<FoldExpr>(IsLeftFold, OperatorName, Pack, Init);
+}
+
+// <expression> ::= <unary operator-name> <expression>
+//              ::= <binary operator-name> <expression> <expression>
+//              ::= <ternary operator-name> <expression> <expression> <expression>
+//              ::= cl <expression>+ E                                   # call
+//              ::= cv <type> <expression>                               # conversion with one argument
+//              ::= cv <type> _ <expression>* E                          # conversion with a different number of arguments
+//              ::= [gs] nw <expression>* _ <type> E                     # new (expr-list) type
+//              ::= [gs] nw <expression>* _ <type> <initializer>         # new (expr-list) type (init)
+//              ::= [gs] na <expression>* _ <type> E                     # new[] (expr-list) type
+//              ::= [gs] na <expression>* _ <type> <initializer>         # new[] (expr-list) type (init)
+//              ::= [gs] dl <expression>                                 # delete expression
+//              ::= [gs] da <expression>                                 # delete[] expression
+//              ::= pp_ <expression>                                     # prefix ++
+//              ::= mm_ <expression>                                     # prefix --
+//              ::= ti <type>                                            # typeid (type)
+//              ::= te <expression>                                      # typeid (expression)
+//              ::= dc <type> <expression>                               # dynamic_cast<type> (expression)
+//              ::= sc <type> <expression>                               # static_cast<type> (expression)
+//              ::= cc <type> <expression>                               # const_cast<type> (expression)
+//              ::= rc <type> <expression>                               # reinterpret_cast<type> (expression)
+//              ::= st <type>                                            # sizeof (a type)
+//              ::= sz <expression>                                      # sizeof (an expression)
+//              ::= at <type>                                            # alignof (a type)
+//              ::= az <expression>                                      # alignof (an expression)
+//              ::= nx <expression>                                      # noexcept (expression)
+//              ::= <template-param>
+//              ::= <function-param>
+//              ::= dt <expression> <unresolved-name>                    # expr.name
+//              ::= pt <expression> <unresolved-name>                    # expr->name
+//              ::= ds <expression> <expression>                         # expr.*expr
+//              ::= sZ <template-param>                                  # size of a parameter pack
+//              ::= sZ <function-param>                                  # size of a function parameter pack
+//              ::= sP <template-arg>* E                                 # sizeof...(T), size of a captured template parameter pack from an alias template
+//              ::= sp <expression>                                      # pack expansion
+//              ::= tw <expression>                                      # throw expression
+//              ::= tr                                                   # throw with no operand (rethrow)
+//              ::= <unresolved-name>                                    # f(p), N::f(p), ::f(p),
+//                                                                       # freestanding dependent name (e.g., T::x),
+//                                                                       # objectless nonstatic member reference
+//              ::= fL <binary-operator-name> <expression> <expression>
+//              ::= fR <binary-operator-name> <expression> <expression>
+//              ::= fl <binary-operator-name> <expression>
+//              ::= fr <binary-operator-name> <expression>
+//              ::= <expr-primary>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseExpr() {
+  bool Global = consumeIf("gs");
+  if (numLeft() < 2)
+    return nullptr;
+
+  switch (*First) {
+  case 'L':
+    return getDerived().parseExprPrimary();
+  case 'T':
+    return getDerived().parseTemplateParam();
+  case 'f': {
+    // Disambiguate a fold expression from a <function-param>.
+    if (look(1) == 'p' || (look(1) == 'L' && std::isdigit(look(2))))
+      return getDerived().parseFunctionParam();
+    return getDerived().parseFoldExpr();
+  }
+  case 'a':
+    switch (First[1]) {
+    case 'a':
+      First += 2;
+      return getDerived().parseBinaryExpr("&&");
+    case 'd':
+      First += 2;
+      return getDerived().parsePrefixExpr("&");
+    case 'n':
+      First += 2;
+      return getDerived().parseBinaryExpr("&");
+    case 'N':
+      First += 2;
+      return getDerived().parseBinaryExpr("&=");
+    case 'S':
+      First += 2;
+      return getDerived().parseBinaryExpr("=");
+    case 't': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<EnclosingExpr>("alignof (", Ty, ")");
+    }
+    case 'z': {
+      First += 2;
+      Node *Ty = getDerived().parseExpr();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<EnclosingExpr>("alignof (", Ty, ")");
+    }
+    }
+    return nullptr;
+  case 'c':
+    switch (First[1]) {
+    // cc <type> <expression>                               # const_cast<type>(expression)
+    case 'c': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return Ty;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<CastExpr>("const_cast", Ty, Ex);
+    }
+    // cl <expression>+ E                                   # call
+    case 'l': {
+      First += 2;
+      Node *Callee = getDerived().parseExpr();
+      if (Callee == nullptr)
+        return Callee;
+      size_t ExprsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseExpr();
+        if (E == nullptr)
+          return E;
+        Names.push_back(E);
+      }
+      return make<CallExpr>(Callee, popTrailingNodeArray(ExprsBegin));
+    }
+    case 'm':
+      First += 2;
+      return getDerived().parseBinaryExpr(",");
+    case 'o':
+      First += 2;
+      return getDerived().parsePrefixExpr("~");
+    case 'v':
+      return getDerived().parseConversionExpr();
+    }
+    return nullptr;
+  case 'd':
+    switch (First[1]) {
+    case 'a': {
+      First += 2;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<DeleteExpr>(Ex, Global, /*is_array=*/true);
+    }
+    case 'c': {
+      First += 2;
+      Node *T = getDerived().parseType();
+      if (T == nullptr)
+        return T;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<CastExpr>("dynamic_cast", T, Ex);
+    }
+    case 'e':
+      First += 2;
+      return getDerived().parsePrefixExpr("*");
+    case 'l': {
+      First += 2;
+      Node *E = getDerived().parseExpr();
+      if (E == nullptr)
+        return E;
+      return make<DeleteExpr>(E, Global, /*is_array=*/false);
+    }
+    case 'n':
+      return getDerived().parseUnresolvedName();
+    case 's': {
+      First += 2;
+      Node *LHS = getDerived().parseExpr();
+      if (LHS == nullptr)
+        return nullptr;
+      Node *RHS = getDerived().parseExpr();
+      if (RHS == nullptr)
+        return nullptr;
+      return make<MemberExpr>(LHS, ".*", RHS);
+    }
+    case 't': {
+      First += 2;
+      Node *LHS = getDerived().parseExpr();
+      if (LHS == nullptr)
+        return LHS;
+      Node *RHS = getDerived().parseExpr();
+      if (RHS == nullptr)
+        return nullptr;
+      return make<MemberExpr>(LHS, ".", RHS);
+    }
+    case 'v':
+      First += 2;
+      return getDerived().parseBinaryExpr("/");
+    case 'V':
+      First += 2;
+      return getDerived().parseBinaryExpr("/=");
+    }
+    return nullptr;
+  case 'e':
+    switch (First[1]) {
+    case 'o':
+      First += 2;
+      return getDerived().parseBinaryExpr("^");
+    case 'O':
+      First += 2;
+      return getDerived().parseBinaryExpr("^=");
+    case 'q':
+      First += 2;
+      return getDerived().parseBinaryExpr("==");
+    }
+    return nullptr;
+  case 'g':
+    switch (First[1]) {
+    case 'e':
+      First += 2;
+      return getDerived().parseBinaryExpr(">=");
+    case 't':
+      First += 2;
+      return getDerived().parseBinaryExpr(">");
+    }
+    return nullptr;
+  case 'i':
+    switch (First[1]) {
+    case 'x': {
+      First += 2;
+      Node *Base = getDerived().parseExpr();
+      if (Base == nullptr)
+        return nullptr;
+      Node *Index = getDerived().parseExpr();
+      if (Index == nullptr)
+        return Index;
+      return make<ArraySubscriptExpr>(Base, Index);
+    }
+    case 'l': {
+      First += 2;
+      size_t InitsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseBracedExpr();
+        if (E == nullptr)
+          return nullptr;
+        Names.push_back(E);
+      }
+      return make<InitListExpr>(nullptr, popTrailingNodeArray(InitsBegin));
+    }
+    }
+    return nullptr;
+  case 'l':
+    switch (First[1]) {
+    case 'e':
+      First += 2;
+      return getDerived().parseBinaryExpr("<=");
+    case 's':
+      First += 2;
+      return getDerived().parseBinaryExpr("<<");
+    case 'S':
+      First += 2;
+      return getDerived().parseBinaryExpr("<<=");
+    case 't':
+      First += 2;
+      return getDerived().parseBinaryExpr("<");
+    }
+    return nullptr;
+  case 'm':
+    switch (First[1]) {
+    case 'i':
+      First += 2;
+      return getDerived().parseBinaryExpr("-");
+    case 'I':
+      First += 2;
+      return getDerived().parseBinaryExpr("-=");
+    case 'l':
+      First += 2;
+      return getDerived().parseBinaryExpr("*");
+    case 'L':
+      First += 2;
+      return getDerived().parseBinaryExpr("*=");
+    case 'm':
+      First += 2;
+      if (consumeIf('_'))
+        return getDerived().parsePrefixExpr("--");
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return nullptr;
+      return make<PostfixExpr>(Ex, "--");
+    }
+    return nullptr;
+  case 'n':
+    switch (First[1]) {
+    case 'a':
+    case 'w':
+      return getDerived().parseNewExpr();
+    case 'e':
+      First += 2;
+      return getDerived().parseBinaryExpr("!=");
+    case 'g':
+      First += 2;
+      return getDerived().parsePrefixExpr("-");
+    case 't':
+      First += 2;
+      return getDerived().parsePrefixExpr("!");
+    case 'x':
+      First += 2;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<EnclosingExpr>("noexcept (", Ex, ")");
+    }
+    return nullptr;
+  case 'o':
+    switch (First[1]) {
+    case 'n':
+      return getDerived().parseUnresolvedName();
+    case 'o':
+      First += 2;
+      return getDerived().parseBinaryExpr("||");
+    case 'r':
+      First += 2;
+      return getDerived().parseBinaryExpr("|");
+    case 'R':
+      First += 2;
+      return getDerived().parseBinaryExpr("|=");
+    }
+    return nullptr;
+  case 'p':
+    switch (First[1]) {
+    case 'm':
+      First += 2;
+      return getDerived().parseBinaryExpr("->*");
+    case 'l':
+      First += 2;
+      return getDerived().parseBinaryExpr("+");
+    case 'L':
+      First += 2;
+      return getDerived().parseBinaryExpr("+=");
+    case 'p': {
+      First += 2;
+      if (consumeIf('_'))
+        return getDerived().parsePrefixExpr("++");
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<PostfixExpr>(Ex, "++");
+    }
+    case 's':
+      First += 2;
+      return getDerived().parsePrefixExpr("+");
+    case 't': {
+      First += 2;
+      Node *L = getDerived().parseExpr();
+      if (L == nullptr)
+        return nullptr;
+      Node *R = getDerived().parseExpr();
+      if (R == nullptr)
+        return nullptr;
+      return make<MemberExpr>(L, "->", R);
+    }
+    }
+    return nullptr;
+  case 'q':
+    if (First[1] == 'u') {
+      First += 2;
+      Node *Cond = getDerived().parseExpr();
+      if (Cond == nullptr)
+        return nullptr;
+      Node *LHS = getDerived().parseExpr();
+      if (LHS == nullptr)
+        return nullptr;
+      Node *RHS = getDerived().parseExpr();
+      if (RHS == nullptr)
+        return nullptr;
+      return make<ConditionalExpr>(Cond, LHS, RHS);
+    }
+    return nullptr;
+  case 'r':
+    switch (First[1]) {
+    case 'c': {
+      First += 2;
+      Node *T = getDerived().parseType();
+      if (T == nullptr)
+        return T;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<CastExpr>("reinterpret_cast", T, Ex);
+    }
+    case 'm':
+      First += 2;
+      return getDerived().parseBinaryExpr("%");
+    case 'M':
+      First += 2;
+      return getDerived().parseBinaryExpr("%=");
+    case 's':
+      First += 2;
+      return getDerived().parseBinaryExpr(">>");
+    case 'S':
+      First += 2;
+      return getDerived().parseBinaryExpr(">>=");
+    }
+    return nullptr;
+  case 's':
+    switch (First[1]) {
+    case 'c': {
+      First += 2;
+      Node *T = getDerived().parseType();
+      if (T == nullptr)
+        return T;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<CastExpr>("static_cast", T, Ex);
+    }
+    case 'p': {
+      First += 2;
+      Node *Child = getDerived().parseExpr();
+      if (Child == nullptr)
+        return nullptr;
+      return make<ParameterPackExpansion>(Child);
+    }
+    case 'r':
+      return getDerived().parseUnresolvedName();
+    case 't': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return Ty;
+      return make<EnclosingExpr>("sizeof (", Ty, ")");
+    }
+    case 'z': {
+      First += 2;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<EnclosingExpr>("sizeof (", Ex, ")");
+    }
+    case 'Z':
+      First += 2;
+      if (look() == 'T') {
+        Node *R = getDerived().parseTemplateParam();
+        if (R == nullptr)
+          return nullptr;
+        return make<SizeofParamPackExpr>(R);
+      } else if (look() == 'f') {
+        Node *FP = getDerived().parseFunctionParam();
+        if (FP == nullptr)
+          return nullptr;
+        return make<EnclosingExpr>("sizeof... (", FP, ")");
+      }
+      return nullptr;
+    case 'P': {
+      First += 2;
+      size_t ArgsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *Arg = getDerived().parseTemplateArg();
+        if (Arg == nullptr)
+          return nullptr;
+        Names.push_back(Arg);
+      }
+      auto *Pack = make<NodeArrayNode>(popTrailingNodeArray(ArgsBegin));
+      if (!Pack)
+        return nullptr;
+      return make<EnclosingExpr>("sizeof... (", Pack, ")");
+    }
+    }
+    return nullptr;
+  case 't':
+    switch (First[1]) {
+    case 'e': {
+      First += 2;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return Ex;
+      return make<EnclosingExpr>("typeid (", Ex, ")");
+    }
+    case 'i': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return Ty;
+      return make<EnclosingExpr>("typeid (", Ty, ")");
+    }
+    case 'l': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      size_t InitsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseBracedExpr();
+        if (E == nullptr)
+          return nullptr;
+        Names.push_back(E);
+      }
+      return make<InitListExpr>(Ty, popTrailingNodeArray(InitsBegin));
+    }
+    case 'r':
+      First += 2;
+      return make<NameType>("throw");
+    case 'w': {
+      First += 2;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return nullptr;
+      return make<ThrowExpr>(Ex);
+    }
+    }
+    return nullptr;
+  case '1':
+  case '2':
+  case '3':
+  case '4':
+  case '5':
+  case '6':
+  case '7':
+  case '8':
+  case '9':
+    return getDerived().parseUnresolvedName();
+  }
+
+  if (consumeIf("u8__uuidoft")) {
+    Node *Ty = getDerived().parseType();
+    if (!Ty)
+      return nullptr;
+    return make<UUIDOfExpr>(Ty);
+  }
+
+  if (consumeIf("u8__uuidofz")) {
+    Node *Ex = getDerived().parseExpr();
+    if (!Ex)
+      return nullptr;
+    return make<UUIDOfExpr>(Ex);
+  }
+
+  return nullptr;
+}
+
+// <call-offset> ::= h <nv-offset> _
+//               ::= v <v-offset> _
+//
+// <nv-offset> ::= <offset number>
+//               # non-virtual base override
+//
+// <v-offset>  ::= <offset number> _ <virtual offset number>
+//               # virtual base override, with vcall offset
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parseCallOffset() {
+  // Just scan through the call offset, we never add this information into the
+  // output.
+  if (consumeIf('h'))
+    return parseNumber(true).empty() || !consumeIf('_');
+  if (consumeIf('v'))
+    return parseNumber(true).empty() || !consumeIf('_') ||
+           parseNumber(true).empty() || !consumeIf('_');
+  return true;
+}
+
+// <special-name> ::= TV <type>    # virtual table
+//                ::= TT <type>    # VTT structure (construction vtable index)
+//                ::= TI <type>    # typeinfo structure
+//                ::= TS <type>    # typeinfo name (null-terminated byte string)
+//                ::= Tc <call-offset> <call-offset> <base encoding>
+//                    # base is the nominal target function of thunk
+//                    # first call-offset is 'this' adjustment
+//                    # second call-offset is result adjustment
+//                ::= T <call-offset> <base encoding>
+//                    # base is the nominal target function of thunk
+//                ::= GV <object name> # Guard variable for one-time initialization
+//                                     # No <type>
+//                ::= TW <object name> # Thread-local wrapper
+//                ::= TH <object name> # Thread-local initialization
+//                ::= GR <object name> _             # First temporary
+//                ::= GR <object name> <seq-id> _    # Subsequent temporaries
+//      extension ::= TC <first type> <number> _ <second type> # construction vtable for second-in-first
+//      extension ::= GR <object name> # reference temporary for object
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSpecialName() {
+  switch (look()) {
+  case 'T':
+    switch (look(1)) {
+    // TV <type>    # virtual table
+    case 'V': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("vtable for ", Ty);
+    }
+    // TT <type>    # VTT structure (construction vtable index)
+    case 'T': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("VTT for ", Ty);
+    }
+    // TI <type>    # typeinfo structure
+    case 'I': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("typeinfo for ", Ty);
+    }
+    // TS <type>    # typeinfo name (null-terminated byte string)
+    case 'S': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("typeinfo name for ", Ty);
+    }
+    // Tc <call-offset> <call-offset> <base encoding>
+    case 'c': {
+      First += 2;
+      if (parseCallOffset() || parseCallOffset())
+        return nullptr;
+      Node *Encoding = getDerived().parseEncoding();
+      if (Encoding == nullptr)
+        return nullptr;
+      return make<SpecialName>("covariant return thunk to ", Encoding);
+    }
+    // extension ::= TC <first type> <number> _ <second type>
+    //               # construction vtable for second-in-first
+    case 'C': {
+      First += 2;
+      Node *FirstType = getDerived().parseType();
+      if (FirstType == nullptr)
+        return nullptr;
+      if (parseNumber(true).empty() || !consumeIf('_'))
+        return nullptr;
+      Node *SecondType = getDerived().parseType();
+      if (SecondType == nullptr)
+        return nullptr;
+      return make<CtorVtableSpecialName>(SecondType, FirstType);
+    }
+    // TW <object name> # Thread-local wrapper
+    case 'W': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("thread-local wrapper routine for ", Name);
+    }
+    // TH <object name> # Thread-local initialization
+    case 'H': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("thread-local initialization routine for ", Name);
+    }
+    // T <call-offset> <base encoding>
+    default: {
+      ++First;
+      bool IsVirt = look() == 'v';
+      if (parseCallOffset())
+        return nullptr;
+      Node *BaseEncoding = getDerived().parseEncoding();
+      if (BaseEncoding == nullptr)
+        return nullptr;
+      if (IsVirt)
+        return make<SpecialName>("virtual thunk to ", BaseEncoding);
+      else
+        return make<SpecialName>("non-virtual thunk to ", BaseEncoding);
+    }
+    }
+  case 'G':
+    switch (look(1)) {
+    // GV <object name> # Guard variable for one-time initialization
+    case 'V': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("guard variable for ", Name);
+    }
+    // GR <object name> # reference temporary for object
+    // GR <object name> _             # First temporary
+    // GR <object name> <seq-id> _    # Subsequent temporaries
+    case 'R': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      size_t Count;
+      bool ParsedSeqId = !parseSeqId(&Count);
+      if (!consumeIf('_') && ParsedSeqId)
+        return nullptr;
+      return make<SpecialName>("reference temporary for ", Name);
+    }
+    }
+  }
+  return nullptr;
+}
+
+// <encoding> ::= <function name> <bare-function-type>
+//            ::= <data name>
+//            ::= <special-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseEncoding() {
+  if (look() == 'G' || look() == 'T')
+    return getDerived().parseSpecialName();
+
+  auto IsEndOfEncoding = [&] {
+    // The set of chars that can potentially follow an <encoding> (none of which
+    // can start a <type>). Enumerating these allows us to avoid speculative
+    // parsing.
+    return numLeft() == 0 || look() == 'E' || look() == '.' || look() == '_';
+  };
+
+  NameState NameInfo(this);
+  Node *Name = getDerived().parseName(&NameInfo);
+  if (Name == nullptr)
+    return nullptr;
+
+  if (resolveForwardTemplateRefs(NameInfo))
+    return nullptr;
+
+  if (IsEndOfEncoding())
+    return Name;
+
+  Node *Attrs = nullptr;
+  if (consumeIf("Ua9enable_ifI")) {
+    size_t BeforeArgs = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+    Attrs = make<EnableIfAttr>(popTrailingNodeArray(BeforeArgs));
+    if (!Attrs)
+      return nullptr;
+  }
+
+  Node *ReturnType = nullptr;
+  if (!NameInfo.CtorDtorConversion && NameInfo.EndsWithTemplateArgs) {
+    ReturnType = getDerived().parseType();
+    if (ReturnType == nullptr)
+      return nullptr;
+  }
+
+  if (consumeIf('v'))
+    return make<FunctionEncoding>(ReturnType, Name, NodeArray(),
+                                  Attrs, NameInfo.CVQualifiers,
+                                  NameInfo.ReferenceQualifier);
+
+  size_t ParamsBegin = Names.size();
+  do {
+    Node *Ty = getDerived().parseType();
+    if (Ty == nullptr)
+      return nullptr;
+    Names.push_back(Ty);
+  } while (!IsEndOfEncoding());
+
+  return make<FunctionEncoding>(ReturnType, Name,
+                                popTrailingNodeArray(ParamsBegin),
+                                Attrs, NameInfo.CVQualifiers,
+                                NameInfo.ReferenceQualifier);
+}
+
+template <class Float>
+struct FloatData;
+
+template <>
+struct FloatData<float>
+{
+    static const size_t mangled_size = 8;
+    static const size_t max_demangled_size = 24;
+    static constexpr const char* spec = "%af";
+};
+
+template <>
+struct FloatData<double>
+{
+    static const size_t mangled_size = 16;
+    static const size_t max_demangled_size = 32;
+    static constexpr const char* spec = "%a";
+};
+
+template <>
+struct FloatData<long double>
+{
+#if defined(__mips__) && defined(__mips_n64) || defined(__aarch64__) || \
+    defined(__wasm__)
+    static const size_t mangled_size = 32;
+#elif defined(__arm__) || defined(__mips__) || defined(__hexagon__)
+    static const size_t mangled_size = 16;
+#else
+    static const size_t mangled_size = 20;  // May need to be adjusted to 16 or 24 on other platforms
+#endif
+    static const size_t max_demangled_size = 40;
+    static constexpr const char *spec = "%LaL";
+};
+
+template <typename Alloc, typename Derived>
+template <class Float>
+Node *AbstractManglingParser<Alloc, Derived>::parseFloatingLiteral() {
+  const size_t N = FloatData<Float>::mangled_size;
+  if (numLeft() <= N)
+    return nullptr;
+  StringView Data(First, First + N);
+  for (char C : Data)
+    if (!std::isxdigit(C))
+      return nullptr;
+  First += N;
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<FloatLiteralImpl<Float>>(Data);
+}
+
+// <seq-id> ::= <0-9A-Z>+
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parseSeqId(size_t *Out) {
+  if (!(look() >= '0' && look() <= '9') &&
+      !(look() >= 'A' && look() <= 'Z'))
+    return true;
+
+  size_t Id = 0;
+  while (true) {
+    if (look() >= '0' && look() <= '9') {
+      Id *= 36;
+      Id += static_cast<size_t>(look() - '0');
+    } else if (look() >= 'A' && look() <= 'Z') {
+      Id *= 36;
+      Id += static_cast<size_t>(look() - 'A') + 10;
+    } else {
+      *Out = Id;
+      return false;
+    }
+    ++First;
+  }
+}
+
+// <substitution> ::= S <seq-id> _
+//                ::= S_
+// <substitution> ::= Sa # ::std::allocator
+// <substitution> ::= Sb # ::std::basic_string
+// <substitution> ::= Ss # ::std::basic_string < char,
+//                                               ::std::char_traits<char>,
+//                                               ::std::allocator<char> >
+// <substitution> ::= Si # ::std::basic_istream<char,  std::char_traits<char> >
+// <substitution> ::= So # ::std::basic_ostream<char,  std::char_traits<char> >
+// <substitution> ::= Sd # ::std::basic_iostream<char, std::char_traits<char> >
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSubstitution() {
+  if (!consumeIf('S'))
+    return nullptr;
+
+  if (std::islower(look())) {
+    Node *SpecialSub;
+    switch (look()) {
+    case 'a':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::allocator);
+      break;
+    case 'b':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::basic_string);
+      break;
+    case 's':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::string);
+      break;
+    case 'i':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::istream);
+      break;
+    case 'o':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::ostream);
+      break;
+    case 'd':
+      ++First;
+      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::iostream);
+      break;
+    default:
+      return nullptr;
+    }
+    if (!SpecialSub)
+      return nullptr;
+    // Itanium C++ ABI 5.1.2: If a name that would use a built-in <substitution>
+    // has ABI tags, the tags are appended to the substitution; the result is a
+    // substitutable component.
+    Node *WithTags = getDerived().parseAbiTags(SpecialSub);
+    if (WithTags != SpecialSub) {
+      Subs.push_back(WithTags);
+      SpecialSub = WithTags;
+    }
+    return SpecialSub;
+  }
+
+  //                ::= S_
+  if (consumeIf('_')) {
+    if (Subs.empty())
+      return nullptr;
+    return Subs[0];
+  }
+
+  //                ::= S <seq-id> _
+  size_t Index = 0;
+  if (parseSeqId(&Index))
+    return nullptr;
+  ++Index;
+  if (!consumeIf('_') || Index >= Subs.size())
+    return nullptr;
+  return Subs[Index];
+}
+
+// <template-param> ::= T_    # first template parameter
+//                  ::= T <parameter-2 non-negative number> _
+//                  ::= TL <level-1> __
+//                  ::= TL <level-1> _ <parameter-2 non-negative number> _
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParam() {
+  if (!consumeIf('T'))
+    return nullptr;
+
+  size_t Level = 0;
+  if (consumeIf('L')) {
+    if (parsePositiveInteger(&Level))
+      return nullptr;
+    ++Level;
+    if (!consumeIf('_'))
+      return nullptr;
+  }
+
+  size_t Index = 0;
+  if (!consumeIf('_')) {
+    if (parsePositiveInteger(&Index))
+      return nullptr;
+    ++Index;
+    if (!consumeIf('_'))
+      return nullptr;
+  }
+
+  // If we're in a context where this <template-param> refers to a
+  // <template-arg> further ahead in the mangled name (currently just conversion
+  // operator types), then we should only look it up in the right context.
+  // This can only happen at the outermost level.
+  if (PermitForwardTemplateReferences && Level == 0) {
+    Node *ForwardRef = make<ForwardTemplateReference>(Index);
+    if (!ForwardRef)
+      return nullptr;
+    assert(ForwardRef->getKind() == Node::KForwardTemplateReference);
+    ForwardTemplateRefs.push_back(
+        static_cast<ForwardTemplateReference *>(ForwardRef));
+    return ForwardRef;
+  }
+
+  if (Level >= TemplateParams.size() || !TemplateParams[Level] ||
+      Index >= TemplateParams[Level]->size()) {
+    // Itanium ABI 5.1.8: In a generic lambda, uses of auto in the parameter
+    // list are mangled as the corresponding artificial template type parameter.
+    if (ParsingLambdaParamsAtLevel == Level && Level <= TemplateParams.size()) {
+      // This will be popped by the ScopedTemplateParamList in
+      // parseUnnamedTypeName.
+      if (Level == TemplateParams.size())
+        TemplateParams.push_back(nullptr);
+      return make<NameType>("auto");
+    }
+
+    return nullptr;
+  }
+
+  return (*TemplateParams[Level])[Index];
+}
+
+// <template-param-decl> ::= Ty                          # type parameter
+//                       ::= Tn <type>                   # non-type parameter
+//                       ::= Tt <template-param-decl>* E # template parameter
+//                       ::= Tp <template-param-decl>    # parameter pack
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParamDecl() {
+  auto InventTemplateParamName = [&](TemplateParamKind Kind) {
+    unsigned Index = NumSyntheticTemplateParameters[(int)Kind]++;
+    Node *N = make<SyntheticTemplateParamName>(Kind, Index);
+    if (N) TemplateParams.back()->push_back(N);
+    return N;
+  };
+
+  if (consumeIf("Ty")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::Type);
+    if (!Name)
+      return nullptr;
+    return make<TypeTemplateParamDecl>(Name);
+  }
+
+  if (consumeIf("Tn")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::NonType);
+    if (!Name)
+      return nullptr;
+    Node *Type = parseType();
+    if (!Type)
+      return nullptr;
+    return make<NonTypeTemplateParamDecl>(Name, Type);
+  }
+
+  if (consumeIf("Tt")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::Template);
+    if (!Name)
+      return nullptr;
+    size_t ParamsBegin = Names.size();
+    ScopedTemplateParamList TemplateTemplateParamParams(this);
+    while (!consumeIf("E")) {
+      Node *P = parseTemplateParamDecl();
+      if (!P)
+        return nullptr;
+      Names.push_back(P);
+    }
+    NodeArray Params = popTrailingNodeArray(ParamsBegin);
+    return make<TemplateTemplateParamDecl>(Name, Params);
+  }
+
+  if (consumeIf("Tp")) {
+    Node *P = parseTemplateParamDecl();
+    if (!P)
+      return nullptr;
+    return make<TemplateParamPackDecl>(P);
+  }
+
+  return nullptr;
+}
+
+// <template-arg> ::= <type>                    # type or template
+//                ::= X <expression> E          # expression
+//                ::= <expr-primary>            # simple expressions
+//                ::= J <template-arg>* E       # argument pack
+//                ::= LZ <encoding> E           # extension
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateArg() {
+  switch (look()) {
+  case 'X': {
+    ++First;
+    Node *Arg = getDerived().parseExpr();
+    if (Arg == nullptr || !consumeIf('E'))
+      return nullptr;
+    return Arg;
+  }
+  case 'J': {
+    ++First;
+    size_t ArgsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+    NodeArray Args = popTrailingNodeArray(ArgsBegin);
+    return make<TemplateArgumentPack>(Args);
+  }
+  case 'L': {
+    //                ::= LZ <encoding> E           # extension
+    if (look(1) == 'Z') {
+      First += 2;
+      Node *Arg = getDerived().parseEncoding();
+      if (Arg == nullptr || !consumeIf('E'))
+        return nullptr;
+      return Arg;
+    }
+    //                ::= <expr-primary>            # simple expressions
+    return getDerived().parseExprPrimary();
+  }
+  default:
+    return getDerived().parseType();
+  }
+}
+
+// <template-args> ::= I <template-arg>* E
+//     extension, the abi says <template-arg>+
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseTemplateArgs(bool TagTemplates) {
+  if (!consumeIf('I'))
+    return nullptr;
+
+  // <template-params> refer to the innermost <template-args>. Clear out any
+  // outer args that we may have inserted into TemplateParams.
+  if (TagTemplates) {
+    TemplateParams.clear();
+    TemplateParams.push_back(&OuterTemplateParams);
+    OuterTemplateParams.clear();
+  }
+
+  size_t ArgsBegin = Names.size();
+  while (!consumeIf('E')) {
+    if (TagTemplates) {
+      auto OldParams = std::move(TemplateParams);
+      Node *Arg = getDerived().parseTemplateArg();
+      TemplateParams = std::move(OldParams);
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+      Node *TableEntry = Arg;
+      if (Arg->getKind() == Node::KTemplateArgumentPack) {
+        TableEntry = make<ParameterPack>(
+            static_cast<TemplateArgumentPack*>(TableEntry)->getElements());
+        if (!TableEntry)
+          return nullptr;
+      }
+      TemplateParams.back()->push_back(TableEntry);
+    } else {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+  }
+  return make<TemplateArgs>(popTrailingNodeArray(ArgsBegin));
+}
+
+// <mangled-name> ::= _Z <encoding>
+//                ::= <type>
+// extension      ::= ___Z <encoding> _block_invoke
+// extension      ::= ___Z <encoding> _block_invoke<decimal-digit>+
+// extension      ::= ___Z <encoding> _block_invoke_<decimal-digit>+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parse() {
+  if (consumeIf("_Z") || consumeIf("__Z")) {
+    Node *Encoding = getDerived().parseEncoding();
+    if (Encoding == nullptr)
+      return nullptr;
+    if (look() == '.') {
+      Encoding = make<DotSuffix>(Encoding, StringView(First, Last));
+      First = Last;
+    }
+    if (numLeft() != 0)
+      return nullptr;
+    return Encoding;
+  }
+
+  if (consumeIf("___Z") || consumeIf("____Z")) {
+    Node *Encoding = getDerived().parseEncoding();
+    if (Encoding == nullptr || !consumeIf("_block_invoke"))
+      return nullptr;
+    bool RequireNumber = consumeIf('_');
+    if (parseNumber().empty() && RequireNumber)
+      return nullptr;
+    if (look() == '.')
+      First = Last;
+    if (numLeft() != 0)
+      return nullptr;
+    return make<SpecialName>("invocation function for block in ", Encoding);
+  }
+
+  Node *Ty = getDerived().parseType();
+  if (numLeft() != 0)
+    return nullptr;
+  return Ty;
+}
+
+template <typename Alloc>
+struct ManglingParser : AbstractManglingParser<ManglingParser<Alloc>, Alloc> {
+  using AbstractManglingParser<ManglingParser<Alloc>,
+                               Alloc>::AbstractManglingParser;
+};
+
+DEMANGLE_NAMESPACE_END
+
+#endif // DEMANGLE_ITANIUMDEMANGLE_H
diff --git a/lib/libcxxabi/src/demangle/README.txt b/lib/libcxxabi/src/demangle/README.txt
new file mode 100644
index 0000000000..514ff6dd16
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/README.txt
@@ -0,0 +1,52 @@
+Itanium Name Demangler Library
+==============================
+
+Introduction
+------------
+
+This directory contains the generic itanium name demangler library. The main
+purpose of the library is to demangle C++ symbols, i.e. convert the string
+"_Z1fv" into "f()". You can also use the CRTP base ManglingParser to perform
+some simple analysis on the mangled name, or (in LLVM) use the opaque
+ItaniumPartialDemangler to query the demangled AST.
+
+Why are there multiple copies of the this library in the source tree?
+---------------------------------------------------------------------
+
+This directory is mirrored between libcxxabi/demangle and
+llvm/include/llvm/Demangle. The simple reason for this is that both projects
+need to demangle symbols, but neither can depend on each other. libcxxabi needs
+the demangler to implement __cxa_demangle, which is part of the itanium ABI
+spec. LLVM needs a copy for a bunch of places, but doesn't want to use the
+system's __cxa_demangle because it a) might not be available (i.e., on Windows),
+and b) probably isn't that up-to-date on the latest language features.
+
+The copy of the demangler in LLVM has some extra stuff that aren't needed in
+libcxxabi (ie, the MSVC demangler, ItaniumPartialDemangler), which depend on the
+shared generic components. Despite these differences, we want to keep the "core"
+generic demangling library identical between both copies to simplify development
+and testing.
+
+If you're working on the generic library, then do the work first in libcxxabi,
+then run the cp-to-llvm.sh script in src/demangle. This script takes as an
+argument the path to llvm, and re-copies the changes you made to libcxxabi over.
+Note that this script just blindly overwrites all changes to the generic library
+in llvm, so be careful.
+
+Because the core demangler needs to work in libcxxabi, everything needs to be
+declared in an anonymous namespace (see DEMANGLE_NAMESPACE_BEGIN), and you can't
+introduce any code that depends on the libcxx dylib.
+
+Hopefully, when LLVM becomes a monorepo, we can de-duplicate this code, and have
+both LLVM and libcxxabi depend on a shared demangler library.
+
+Testing
+-------
+
+The tests are split up between libcxxabi/test/{unit,}test_demangle.cpp, and
+llvm/unittest/Demangle. The llvm directory should only get tests for stuff not
+included in the core library. In the future though, we should probably move all
+the tests to LLVM.
+
+It is also a really good idea to run libFuzzer after non-trivial changes, see
+libcxxabi/fuzz/cxa_demangle_fuzzer.cpp and https://llvm.org/docs/LibFuzzer.html.
diff --git a/lib/libcxxabi/src/demangle/StringView.h b/lib/libcxxabi/src/demangle/StringView.h
new file mode 100644
index 0000000000..ceb6c79580
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/StringView.h
@@ -0,0 +1,126 @@
+//===--- StringView.h -------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// FIXME: Use std::string_view instead when we support C++17.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_STRINGVIEW_H
+#define DEMANGLE_STRINGVIEW_H
+
+#include "DemangleConfig.h"
+#include <algorithm>
+#include <cassert>
+#include <cstring>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+class StringView {
+  const char *First;
+  const char *Last;
+
+public:
+  static const size_t npos = ~size_t(0);
+
+  template <size_t N>
+  StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
+  StringView(const char *First_, const char *Last_)
+      : First(First_), Last(Last_) {}
+  StringView(const char *First_, size_t Len)
+      : First(First_), Last(First_ + Len) {}
+  StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
+  StringView() : First(nullptr), Last(nullptr) {}
+
+  StringView substr(size_t From) const {
+    return StringView(begin() + From, size() - From);
+  }
+
+  size_t find(char C, size_t From = 0) const {
+    size_t FindBegin = std::min(From, size());
+    // Avoid calling memchr with nullptr.
+    if (FindBegin < size()) {
+      // Just forward to memchr, which is faster than a hand-rolled loop.
+      if (const void *P = ::memchr(First + FindBegin, C, size() - FindBegin))
+        return size_t(static_cast<const char *>(P) - First);
+    }
+    return npos;
+  }
+
+  StringView substr(size_t From, size_t To) const {
+    if (To >= size())
+      To = size() - 1;
+    if (From >= size())
+      From = size() - 1;
+    return StringView(First + From, First + To);
+  }
+
+  StringView dropFront(size_t N = 1) const {
+    if (N >= size())
+      N = size();
+    return StringView(First + N, Last);
+  }
+
+  StringView dropBack(size_t N = 1) const {
+    if (N >= size())
+      N = size();
+    return StringView(First, Last - N);
+  }
+
+  char front() const {
+    assert(!empty());
+    return *begin();
+  }
+
+  char back() const {
+    assert(!empty());
+    return *(end() - 1);
+  }
+
+  char popFront() {
+    assert(!empty());
+    return *First++;
+  }
+
+  bool consumeFront(char C) {
+    if (!startsWith(C))
+      return false;
+    *this = dropFront(1);
+    return true;
+  }
+
+  bool consumeFront(StringView S) {
+    if (!startsWith(S))
+      return false;
+    *this = dropFront(S.size());
+    return true;
+  }
+
+  bool startsWith(char C) const { return !empty() && *begin() == C; }
+
+  bool startsWith(StringView Str) const {
+    if (Str.size() > size())
+      return false;
+    return std::equal(Str.begin(), Str.end(), begin());
+  }
+
+  const char &operator[](size_t Idx) const { return *(begin() + Idx); }
+
+  const char *begin() const { return First; }
+  const char *end() const { return Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  bool empty() const { return First == Last; }
+};
+
+inline bool operator==(const StringView &LHS, const StringView &RHS) {
+  return LHS.size() == RHS.size() &&
+         std::equal(LHS.begin(), LHS.end(), RHS.begin());
+}
+
+DEMANGLE_NAMESPACE_END
+
+#endif
diff --git a/lib/libcxxabi/src/demangle/Utility.h b/lib/libcxxabi/src/demangle/Utility.h
new file mode 100644
index 0000000000..04e1936ebb
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/Utility.h
@@ -0,0 +1,191 @@
+//===--- Utility.h ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Provide some utility classes for use in the demangler(s).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_UTILITY_H
+#define DEMANGLE_UTILITY_H
+
+#include "StringView.h"
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <iterator>
+#include <limits>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+// Stream that AST nodes write their string representation into after the AST
+// has been parsed.
+class OutputStream {
+  char *Buffer = nullptr;
+  size_t CurrentPosition = 0;
+  size_t BufferCapacity = 0;
+
+  // Ensure there is at least n more positions in buffer.
+  void grow(size_t N) {
+    if (N + CurrentPosition >= BufferCapacity) {
+      BufferCapacity *= 2;
+      if (BufferCapacity < N + CurrentPosition)
+        BufferCapacity = N + CurrentPosition;
+      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
+      if (Buffer == nullptr)
+        std::terminate();
+    }
+  }
+
+  void writeUnsigned(uint64_t N, bool isNeg = false) {
+    // Handle special case...
+    if (N == 0) {
+      *this << '0';
+      return;
+    }
+
+    char Temp[21];
+    char *TempPtr = std::end(Temp);
+
+    while (N) {
+      *--TempPtr = '0' + char(N % 10);
+      N /= 10;
+    }
+
+    // Add negative sign...
+    if (isNeg)
+      *--TempPtr = '-';
+    this->operator<<(StringView(TempPtr, std::end(Temp)));
+  }
+
+public:
+  OutputStream(char *StartBuf, size_t Size)
+      : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {}
+  OutputStream() = default;
+  void reset(char *Buffer_, size_t BufferCapacity_) {
+    CurrentPosition = 0;
+    Buffer = Buffer_;
+    BufferCapacity = BufferCapacity_;
+  }
+
+  /// If a ParameterPackExpansion (or similar type) is encountered, the offset
+  /// into the pack that we're currently printing.
+  unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();
+  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
+
+  OutputStream &operator+=(StringView R) {
+    size_t Size = R.size();
+    if (Size == 0)
+      return *this;
+    grow(Size);
+    std::memmove(Buffer + CurrentPosition, R.begin(), Size);
+    CurrentPosition += Size;
+    return *this;
+  }
+
+  OutputStream &operator+=(char C) {
+    grow(1);
+    Buffer[CurrentPosition++] = C;
+    return *this;
+  }
+
+  OutputStream &operator<<(StringView R) { return (*this += R); }
+
+  OutputStream &operator<<(char C) { return (*this += C); }
+
+  OutputStream &operator<<(long long N) {
+    if (N < 0)
+      writeUnsigned(static_cast<unsigned long long>(-N), true);
+    else
+      writeUnsigned(static_cast<unsigned long long>(N));
+    return *this;
+  }
+
+  OutputStream &operator<<(unsigned long long N) {
+    writeUnsigned(N, false);
+    return *this;
+  }
+
+  OutputStream &operator<<(long N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputStream &operator<<(unsigned long N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  OutputStream &operator<<(int N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputStream &operator<<(unsigned int N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  size_t getCurrentPosition() const { return CurrentPosition; }
+  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
+
+  char back() const {
+    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0';
+  }
+
+  bool empty() const { return CurrentPosition == 0; }
+
+  char *getBuffer() { return Buffer; }
+  char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
+  size_t getBufferCapacity() const { return BufferCapacity; }
+};
+
+template <class T> class SwapAndRestore {
+  T &Restore;
+  T OriginalValue;
+  bool ShouldRestore = true;
+
+public:
+  SwapAndRestore(T &Restore_) : SwapAndRestore(Restore_, Restore_) {}
+
+  SwapAndRestore(T &Restore_, T NewVal)
+      : Restore(Restore_), OriginalValue(Restore) {
+    Restore = std::move(NewVal);
+  }
+  ~SwapAndRestore() {
+    if (ShouldRestore)
+      Restore = std::move(OriginalValue);
+  }
+
+  void shouldRestore(bool ShouldRestore_) { ShouldRestore = ShouldRestore_; }
+
+  void restoreNow(bool Force) {
+    if (!Force && !ShouldRestore)
+      return;
+
+    Restore = std::move(OriginalValue);
+    ShouldRestore = false;
+  }
+
+  SwapAndRestore(const SwapAndRestore &) = delete;
+  SwapAndRestore &operator=(const SwapAndRestore &) = delete;
+};
+
+inline bool initializeOutputStream(char *Buf, size_t *N, OutputStream &S,
+                                   size_t InitSize) {
+  size_t BufferSize;
+  if (Buf == nullptr) {
+    Buf = static_cast<char *>(std::malloc(InitSize));
+    if (Buf == nullptr)
+      return false;
+    BufferSize = InitSize;
+  } else
+    BufferSize = *N;
+
+  S.reset(Buf, BufferSize);
+  return true;
+}
+
+DEMANGLE_NAMESPACE_END
+
+#endif
diff --git a/lib/libcxxabi/src/demangle/cp-to-llvm.sh b/lib/libcxxabi/src/demangle/cp-to-llvm.sh
new file mode 100755
index 0000000000..808abbcd99
--- /dev/null
+++ b/lib/libcxxabi/src/demangle/cp-to-llvm.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# Copies the 'demangle' library, excluding 'DemangleConfig.h', to llvm. If no
+# llvm directory is specified, then assume a monorepo layout.
+
+set -e
+
+FILES="ItaniumDemangle.h StringView.h Utility.h README.txt"
+LLVM_DEMANGLE_DIR=$1
+
+if [[ -z "$LLVM_DEMANGLE_DIR" ]]; then
+    LLVM_DEMANGLE_DIR="../../../llvm/include/llvm/Demangle"
+fi
+
+if [[ ! -d "$LLVM_DEMANGLE_DIR" ]]; then
+    echo "No such directory: $LLVM_DEMANGLE_DIR" >&2
+    exit 1
+fi
+
+read -p "This will overwrite the copies of $FILES in $LLVM_DEMANGLE_DIR; are you sure? [y/N]" -n 1 -r ANSWER
+echo
+
+if [[ $ANSWER =~ ^[Yy]$ ]]; then
+    for I in $FILES ; do
+        cp $I $LLVM_DEMANGLE_DIR/$I
+    done
+fi
diff --git a/lib/libcxxabi/src/fallback_malloc.cpp b/lib/libcxxabi/src/fallback_malloc.cpp
new file mode 100644
index 0000000000..fdae40764a
--- /dev/null
+++ b/lib/libcxxabi/src/fallback_malloc.cpp
@@ -0,0 +1,259 @@
+//===------------------------ fallback_malloc.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Define _LIBCPP_BUILDING_LIBRARY to ensure _LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
+// is only defined when libc aligned allocation is not available.
+#define _LIBCPP_BUILDING_LIBRARY
+#include "fallback_malloc.h"
+
+#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
+#include <stdlib.h> // for malloc, calloc, free
+#include <string.h> // for memset
+
+//  A small, simple heap manager based (loosely) on
+//  the startup heap manager from FreeBSD, optimized for space.
+//
+//  Manages a fixed-size memory pool, supports malloc and free only.
+//  No support for realloc.
+//
+//  Allocates chunks in multiples of four bytes, with a four byte header
+//  for each chunk. The overhead of each chunk is kept low by keeping pointers
+//  as two byte offsets within the heap, rather than (4 or 8 byte) pointers.
+
+namespace {
+
+// When POSIX threads are not available, make the mutex operations a nop
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+_LIBCPP_SAFE_STATIC
+static std::__libcpp_mutex_t heap_mutex = _LIBCPP_MUTEX_INITIALIZER;
+#else
+static void* heap_mutex = 0;
+#endif
+
+class mutexor {
+public:
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+  mutexor(std::__libcpp_mutex_t* m) : mtx_(m) {
+    std::__libcpp_mutex_lock(mtx_);
+  }
+  ~mutexor() { std::__libcpp_mutex_unlock(mtx_); }
+#else
+  mutexor(void*) {}
+  ~mutexor() {}
+#endif
+private:
+  mutexor(const mutexor& rhs);
+  mutexor& operator=(const mutexor& rhs);
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+  std::__libcpp_mutex_t* mtx_;
+#endif
+};
+
+static const size_t HEAP_SIZE = 512;
+char heap[HEAP_SIZE] __attribute__((aligned));
+
+typedef unsigned short heap_offset;
+typedef unsigned short heap_size;
+
+struct heap_node {
+  heap_offset next_node; // offset into heap
+  heap_size len;         // size in units of "sizeof(heap_node)"
+};
+
+static const heap_node* list_end =
+    (heap_node*)(&heap[HEAP_SIZE]); // one past the end of the heap
+static heap_node* freelist = NULL;
+
+heap_node* node_from_offset(const heap_offset offset) {
+  return (heap_node*)(heap + (offset * sizeof(heap_node)));
+}
+
+heap_offset offset_from_node(const heap_node* ptr) {
+  return static_cast<heap_offset>(
+      static_cast<size_t>(reinterpret_cast<const char*>(ptr) - heap) /
+      sizeof(heap_node));
+}
+
+void init_heap() {
+  freelist = (heap_node*)heap;
+  freelist->next_node = offset_from_node(list_end);
+  freelist->len = HEAP_SIZE / sizeof(heap_node);
+}
+
+//  How big a chunk we allocate
+size_t alloc_size(size_t len) {
+  return (len + sizeof(heap_node) - 1) / sizeof(heap_node) + 1;
+}
+
+bool is_fallback_ptr(void* ptr) {
+  return ptr >= heap && ptr < (heap + HEAP_SIZE);
+}
+
+void* fallback_malloc(size_t len) {
+  heap_node *p, *prev;
+  const size_t nelems = alloc_size(len);
+  mutexor mtx(&heap_mutex);
+
+  if (NULL == freelist)
+    init_heap();
+
+  //  Walk the free list, looking for a "big enough" chunk
+  for (p = freelist, prev = 0; p && p != list_end;
+       prev = p, p = node_from_offset(p->next_node)) {
+
+    if (p->len > nelems) { //  chunk is larger, shorten, and return the tail
+      heap_node* q;
+
+      p->len = static_cast<heap_size>(p->len - nelems);
+      q = p + p->len;
+      q->next_node = 0;
+      q->len = static_cast<heap_size>(nelems);
+      return (void*)(q + 1);
+    }
+
+    if (p->len == nelems) { // exact size match
+      if (prev == 0)
+        freelist = node_from_offset(p->next_node);
+      else
+        prev->next_node = p->next_node;
+      p->next_node = 0;
+      return (void*)(p + 1);
+    }
+  }
+  return NULL; // couldn't find a spot big enough
+}
+
+//  Return the start of the next block
+heap_node* after(struct heap_node* p) { return p + p->len; }
+
+void fallback_free(void* ptr) {
+  struct heap_node* cp = ((struct heap_node*)ptr) - 1; // retrieve the chunk
+  struct heap_node *p, *prev;
+
+  mutexor mtx(&heap_mutex);
+
+#ifdef DEBUG_FALLBACK_MALLOC
+  std::cout << "Freeing item at " << offset_from_node(cp) << " of size "
+            << cp->len << std::endl;
+#endif
+
+  for (p = freelist, prev = 0; p && p != list_end;
+       prev = p, p = node_from_offset(p->next_node)) {
+#ifdef DEBUG_FALLBACK_MALLOC
+    std::cout << "  p, cp, after (p), after(cp) " << offset_from_node(p) << ' '
+              << offset_from_node(cp) << ' ' << offset_from_node(after(p))
+              << ' ' << offset_from_node(after(cp)) << std::endl;
+#endif
+    if (after(p) == cp) {
+#ifdef DEBUG_FALLBACK_MALLOC
+      std::cout << "  Appending onto chunk at " << offset_from_node(p)
+                << std::endl;
+#endif
+      p->len = static_cast<heap_size>(
+          p->len + cp->len); // make the free heap_node larger
+      return;
+    } else if (after(cp) == p) { // there's a free heap_node right after
+#ifdef DEBUG_FALLBACK_MALLOC
+      std::cout << "  Appending free chunk at " << offset_from_node(p)
+                << std::endl;
+#endif
+      cp->len = static_cast<heap_size>(cp->len + p->len);
+      if (prev == 0) {
+        freelist = cp;
+        cp->next_node = p->next_node;
+      } else
+        prev->next_node = offset_from_node(cp);
+      return;
+    }
+  }
+//  Nothing to merge with, add it to the start of the free list
+#ifdef DEBUG_FALLBACK_MALLOC
+  std::cout << "  Making new free list entry " << offset_from_node(cp)
+            << std::endl;
+#endif
+  cp->next_node = offset_from_node(freelist);
+  freelist = cp;
+}
+
+#ifdef INSTRUMENT_FALLBACK_MALLOC
+size_t print_free_list() {
+  struct heap_node *p, *prev;
+  heap_size total_free = 0;
+  if (NULL == freelist)
+    init_heap();
+
+  for (p = freelist, prev = 0; p && p != list_end;
+       prev = p, p = node_from_offset(p->next_node)) {
+    std::cout << (prev == 0 ? "" : "  ") << "Offset: " << offset_from_node(p)
+              << "\tsize: " << p->len << " Next: " << p->next_node << std::endl;
+    total_free += p->len;
+  }
+  std::cout << "Total Free space: " << total_free << std::endl;
+  return total_free;
+}
+#endif
+} // end unnamed namespace
+
+namespace __cxxabiv1 {
+
+struct __attribute__((aligned)) __aligned_type {};
+
+void* __aligned_malloc_with_fallback(size_t size) {
+#if defined(_WIN32)
+  if (void* dest = _aligned_malloc(size, alignof(__aligned_type)))
+    return dest;
+#elif defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION)
+  if (void* dest = ::malloc(size))
+    return dest;
+#else
+  if (size == 0)
+    size = 1;
+  void* dest;
+  if (::posix_memalign(&dest, __alignof(__aligned_type), size) == 0)
+    return dest;
+#endif
+  return fallback_malloc(size);
+}
+
+void* __calloc_with_fallback(size_t count, size_t size) {
+  void* ptr = ::calloc(count, size);
+  if (NULL != ptr)
+    return ptr;
+  // if calloc fails, fall back to emergency stash
+  ptr = fallback_malloc(size * count);
+  if (NULL != ptr)
+    ::memset(ptr, 0, size * count);
+  return ptr;
+}
+
+void __aligned_free_with_fallback(void* ptr) {
+  if (is_fallback_ptr(ptr))
+    fallback_free(ptr);
+  else {
+#if defined(_WIN32)
+    ::_aligned_free(ptr);
+#else
+    ::free(ptr);
+#endif
+  }
+}
+
+void __free_with_fallback(void* ptr) {
+  if (is_fallback_ptr(ptr))
+    fallback_free(ptr);
+  else
+    ::free(ptr);
+}
+
+} // namespace __cxxabiv1
diff --git a/lib/libcxxabi/src/fallback_malloc.h b/lib/libcxxabi/src/fallback_malloc.h
new file mode 100644
index 0000000000..5780854519
--- /dev/null
+++ b/lib/libcxxabi/src/fallback_malloc.h
@@ -0,0 +1,28 @@
+//===------------------------- fallback_malloc.h --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _FALLBACK_MALLOC_H
+#define _FALLBACK_MALLOC_H
+
+#include "__cxxabi_config.h"
+#include <stddef.h> // for size_t
+
+namespace __cxxabiv1 {
+
+// Allocate some memory from _somewhere_
+_LIBCXXABI_HIDDEN void * __aligned_malloc_with_fallback(size_t size);
+
+// Allocate and zero-initialize memory from _somewhere_
+_LIBCXXABI_HIDDEN void * __calloc_with_fallback(size_t count, size_t size);
+
+_LIBCXXABI_HIDDEN void __aligned_free_with_fallback(void *ptr);
+_LIBCXXABI_HIDDEN void __free_with_fallback(void *ptr);
+
+} // namespace __cxxabiv1
+
+#endif
diff --git a/lib/libcxxabi/src/include/atomic_support.h b/lib/libcxxabi/src/include/atomic_support.h
new file mode 100644
index 0000000000..4ff45eb93a
--- /dev/null
+++ b/lib/libcxxabi/src/include/atomic_support.h
@@ -0,0 +1,210 @@
+//===----------------------------------------------------------------------===////
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===////
+
+// FIXME: This file is copied from libcxx/src/include/atomic_support.h. Instead
+// of duplicating the file in libc++abi we should require that the libc++
+// sources are available when building libc++abi.
+
+#ifndef ATOMIC_SUPPORT_H
+#define ATOMIC_SUPPORT_H
+
+#include "__config"
+#include "memory" // for __libcpp_relaxed_load
+
+#if defined(__clang__) && __has_builtin(__atomic_load_n)             \
+                       && __has_builtin(__atomic_store_n)            \
+                       && __has_builtin(__atomic_add_fetch)          \
+                       && __has_builtin(__atomic_exchange_n)         \
+                       && __has_builtin(__atomic_compare_exchange_n) \
+                       && defined(__ATOMIC_RELAXED)                  \
+                       && defined(__ATOMIC_CONSUME)                  \
+                       && defined(__ATOMIC_ACQUIRE)                  \
+                       && defined(__ATOMIC_RELEASE)                  \
+                       && defined(__ATOMIC_ACQ_REL)                  \
+                       && defined(__ATOMIC_SEQ_CST)
+#   define _LIBCXXABI_HAS_ATOMIC_BUILTINS
+#elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407
+#   define _LIBCXXABI_HAS_ATOMIC_BUILTINS
+#endif
+
+#if !defined(_LIBCXXABI_HAS_ATOMIC_BUILTINS) && !defined(_LIBCXXABI_HAS_NO_THREADS)
+# if defined(_LIBCPP_WARNING)
+    _LIBCPP_WARNING("Building libc++ without __atomic builtins is unsupported")
+# else
+#   warning Building libc++ without __atomic builtins is unsupported
+# endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+#if defined(_LIBCXXABI_HAS_ATOMIC_BUILTINS) && !defined(_LIBCXXABI_HAS_NO_THREADS)
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed = __ATOMIC_RELAXED,
+    _AO_Consume = __ATOMIC_CONSUME,
+    _AO_Acquire = __ATOMIC_ACQUIRE,
+    _AO_Release = __ATOMIC_RELEASE,
+    _AO_Acq_Rel = __ATOMIC_ACQ_REL,
+    _AO_Seq     = __ATOMIC_SEQ_CST
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int __order = _AO_Seq)
+{
+    __atomic_store_n(__dest, __val, __order);
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    __atomic_store_n(__dest, __val, _AO_Relaxed);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int __order = _AO_Seq)
+{
+    return __atomic_load_n(__val, __order);
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int __order = _AO_Seq)
+{
+    return __atomic_add_fetch(__val, __a, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int __order = _AO_Seq)
+{
+    return __atomic_exchange_n(__target, __value, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int __success_order = _AO_Seq,
+    int __fail_order = _AO_Seq)
+{
+    return __atomic_compare_exchange_n(__val, __expected, __after, true,
+                                       __success_order, __fail_order);
+}
+
+#else // _LIBCPP_HAS_NO_THREADS
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed,
+    _AO_Consume,
+    _AO_Acquire,
+    _AO_Release,
+    _AO_Acq_Rel,
+    _AO_Seq
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int = 0)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int = 0)
+{
+    return *__val;
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int = 0)
+{
+    return *__val += __a;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int  = _AO_Seq)
+{
+    _ValueType old = *__target;
+    *__target = __value;
+    return old;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int = 0, int = 0)
+{
+    if (*__val == *__expected) {
+        *__val = __after;
+        return true;
+    }
+    *__expected = *__val;
+    return false;
+}
+
+#endif // _LIBCPP_HAS_NO_THREADS
+
+} // end namespace
+
+_LIBCPP_END_NAMESPACE_STD
+
+namespace {
+
+template <class IntType>
+class AtomicInt {
+public:
+  using MemoryOrder = std::__libcpp_atomic_order;
+
+  explicit AtomicInt(IntType *b) : b(b) {}
+  AtomicInt(AtomicInt const&) = delete;
+  AtomicInt& operator=(AtomicInt const&) = delete;
+
+  IntType load(MemoryOrder ord) {
+    return std::__libcpp_atomic_load(b, ord);
+  }
+  void store(IntType val, MemoryOrder ord) {
+    std::__libcpp_atomic_store(b, val, ord);
+  }
+  IntType exchange(IntType new_val, MemoryOrder ord) {
+    return std::__libcpp_atomic_exchange(b, new_val, ord);
+  }
+  bool compare_exchange(IntType *expected, IntType desired, MemoryOrder ord_success, MemoryOrder ord_failure) {
+    return std::__libcpp_atomic_compare_exchange(b, expected, desired, ord_success, ord_failure);
+  }
+
+private:
+  IntType *b;
+};
+
+} // end namespace
+
+#endif // ATOMIC_SUPPORT_H
diff --git a/lib/libcxxabi/src/include/refstring.h b/lib/libcxxabi/src/include/refstring.h
new file mode 100644
index 0000000000..5905b5c932
--- /dev/null
+++ b/lib/libcxxabi/src/include/refstring.h
@@ -0,0 +1,131 @@
+//===------------------------ __refstring ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// FIXME: This file is copied from libcxx/src/include/refstring.h. Instead of
+// duplicating the file in libc++abi we should require that the libc++ sources
+// are available when building libc++abi.
+
+#ifndef _LIBCPPABI_REFSTRING_H
+#define _LIBCPPABI_REFSTRING_H
+
+#include <__config>
+#include <stdexcept>
+#include <cstddef>
+#include <cstring>
+#ifdef __APPLE__
+#include <dlfcn.h>
+#include <mach-o/dyld.h>
+#endif
+#include "atomic_support.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace __refstring_imp { namespace {
+typedef int count_t;
+
+struct _Rep_base {
+    std::size_t len;
+    std::size_t cap;
+    count_t     count;
+};
+
+inline _Rep_base* rep_from_data(const char *data_) noexcept {
+    char *data = const_cast<char *>(data_);
+    return reinterpret_cast<_Rep_base *>(data - sizeof(_Rep_base));
+}
+
+inline char * data_from_rep(_Rep_base *rep) noexcept {
+    char *data = reinterpret_cast<char *>(rep);
+    return data + sizeof(*rep);
+}
+
+#if defined(__APPLE__)
+inline
+const char* compute_gcc_empty_string_storage() _NOEXCEPT
+{
+    void* handle = dlopen("/usr/lib/libstdc++.6.dylib", RTLD_NOLOAD);
+    if (handle == nullptr)
+        return nullptr;
+    void* sym = dlsym(handle, "_ZNSs4_Rep20_S_empty_rep_storageE");
+    if (sym == nullptr)
+        return nullptr;
+    return data_from_rep(reinterpret_cast<_Rep_base *>(sym));
+}
+
+inline
+const char*
+get_gcc_empty_string_storage() _NOEXCEPT
+{
+    static const char* p = compute_gcc_empty_string_storage();
+    return p;
+}
+#endif
+
+}} // namespace __refstring_imp
+
+using namespace __refstring_imp;
+
+inline
+__libcpp_refstring::__libcpp_refstring(const char* msg) {
+    std::size_t len = strlen(msg);
+    _Rep_base* rep = static_cast<_Rep_base *>(::operator new(sizeof(*rep) + len + 1));
+    rep->len = len;
+    rep->cap = len;
+    rep->count = 0;
+    char *data = data_from_rep(rep);
+    std::memcpy(data, msg, len + 1);
+    __imp_ = data;
+}
+
+inline
+__libcpp_refstring::__libcpp_refstring(const __libcpp_refstring &s) _NOEXCEPT
+    : __imp_(s.__imp_)
+{
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+}
+
+inline
+__libcpp_refstring& __libcpp_refstring::operator=(__libcpp_refstring const& s) _NOEXCEPT {
+    bool adjust_old_count = __uses_refcount();
+    struct _Rep_base *old_rep = rep_from_data(__imp_);
+    __imp_ = s.__imp_;
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+    if (adjust_old_count)
+    {
+        if (__libcpp_atomic_add(&old_rep->count, count_t(-1)) < 0)
+        {
+            ::operator delete(old_rep);
+        }
+    }
+    return *this;
+}
+
+inline
+__libcpp_refstring::~__libcpp_refstring() {
+    if (__uses_refcount()) {
+        _Rep_base* rep = rep_from_data(__imp_);
+        if (__libcpp_atomic_add(&rep->count, count_t(-1)) < 0) {
+            ::operator delete(rep);
+        }
+    }
+}
+
+inline
+bool __libcpp_refstring::__uses_refcount() const {
+#ifdef __APPLE__
+    return __imp_ != get_gcc_empty_string_storage();
+#else
+    return true;
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif //_LIBCPPABI_REFSTRING_H
diff --git a/lib/libcxxabi/src/private_typeinfo.cpp b/lib/libcxxabi/src/private_typeinfo.cpp
new file mode 100644
index 0000000000..5ce762a22b
--- /dev/null
+++ b/lib/libcxxabi/src/private_typeinfo.cpp
@@ -0,0 +1,1291 @@
+//===----------------------- private_typeinfo.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "private_typeinfo.h"
+
+// The flag _LIBCXX_DYNAMIC_FALLBACK is used to make dynamic_cast more
+// forgiving when type_info's mistakenly have hidden visibility and thus
+// multiple type_infos can exist for a single type.
+//
+// When _LIBCXX_DYNAMIC_FALLBACK is defined, and only in the case where
+// there is a detected inconsistency in the type_info hierarchy during a
+// dynamic_cast, then the equality operation will fall back to using strcmp
+// on type_info names to determine type_info equality.
+//
+// This change happens *only* under dynamic_cast, and only when
+// dynamic_cast is faced with the choice:  abort, or possibly give back the
+// wrong answer.  If when the dynamic_cast is done with this fallback
+// algorithm and an inconsistency is still detected, dynamic_cast will call
+// abort with an appropriate message.
+//
+// The current implementation of _LIBCXX_DYNAMIC_FALLBACK requires a
+// printf-like function called syslog:
+//
+//     void syslog(int facility_priority, const char* format, ...);
+//
+// If you want this functionality but your platform doesn't have syslog,
+// just implement it in terms of fprintf(stderr, ...).
+//
+// _LIBCXX_DYNAMIC_FALLBACK is currently off by default.
+
+// On Windows, typeids are different between DLLs and EXEs, so comparing
+// type_info* will work for typeids from the same compiled file but fail
+// for typeids from a DLL and an executable. Among other things, exceptions
+// are not caught by handlers since can_catch() returns false.
+//
+// Defining _LIBCXX_DYNAMIC_FALLBACK does not help since can_catch() calls
+// is_equal() with use_strcmp=false so the string names are not compared.
+
+#include <string.h>
+
+#ifdef _LIBCXX_DYNAMIC_FALLBACK
+#include "abort_message.h"
+#include <sys/syslog.h>
+#endif
+
+static inline
+bool
+is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
+{
+    // Use std::type_info's default comparison unless we've explicitly asked
+    // for strcmp.
+    if (!use_strcmp)
+        return *x == *y;
+    // Still allow pointer equality to short circut.
+    return x == y || strcmp(x->name(), y->name()) == 0;
+}
+
+namespace __cxxabiv1
+{
+
+// __shim_type_info
+
+__shim_type_info::~__shim_type_info()
+{
+}
+
+void __shim_type_info::noop1() const {}
+void __shim_type_info::noop2() const {}
+
+// __fundamental_type_info
+
+// This miraculously (compiler magic) emits the type_info's for:
+//   1. all of the fundamental types
+//   2. pointers to all of the fundamental types
+//   3. pointers to all of the const fundamental types
+__fundamental_type_info::~__fundamental_type_info()
+{
+}
+
+// __array_type_info
+
+__array_type_info::~__array_type_info()
+{
+}
+
+// __function_type_info
+
+__function_type_info::~__function_type_info()
+{
+}
+
+// __enum_type_info
+
+__enum_type_info::~__enum_type_info()
+{
+}
+
+// __class_type_info
+
+__class_type_info::~__class_type_info()
+{
+}
+
+// __si_class_type_info
+
+__si_class_type_info::~__si_class_type_info()
+{
+}
+
+// __vmi_class_type_info
+
+__vmi_class_type_info::~__vmi_class_type_info()
+{
+}
+
+// __pbase_type_info
+
+__pbase_type_info::~__pbase_type_info()
+{
+}
+
+// __pointer_type_info
+
+__pointer_type_info::~__pointer_type_info()
+{
+}
+
+// __pointer_to_member_type_info
+
+__pointer_to_member_type_info::~__pointer_to_member_type_info()
+{
+}
+
+// can_catch
+
+// A handler is a match for an exception object of type E if
+//   1. The handler is of type cv T or cv T& and E and T are the same type
+//      (ignoring the top-level cv-qualifiers), or
+//   2. the handler is of type cv T or cv T& and T is an unambiguous public
+//       base class of E, or
+//   3. the handler is of type cv1 T* cv2 and E is a pointer type that can be
+//      converted to the type of the handler by either or both of
+//      A. a standard pointer conversion (4.10) not involving conversions to
+//         pointers to private or protected or ambiguous classes
+//      B. a qualification conversion
+//   4. the handler is a pointer or pointer to member type and E is
+//      std::nullptr_t.
+
+// adjustedPtr:
+//
+// catch (A& a) : adjustedPtr == &a
+// catch (A* a) : adjustedPtr == a
+// catch (A** a) : adjustedPtr == a
+//
+// catch (D2& d2) : adjustedPtr == &d2  (d2 is base class of thrown object)
+// catch (D2* d2) : adjustedPtr == d2
+// catch (D2*& d2) : adjustedPtr == d2
+//
+// catch (...) : adjustedPtr == & of the exception
+//
+// If the thrown type is nullptr_t and the caught type is a pointer to
+// member type, adjustedPtr points to a statically-allocated null pointer
+// representation of that type.
+
+// Handles bullet 1
+bool
+__fundamental_type_info::can_catch(const __shim_type_info* thrown_type,
+                                   void*&) const
+{
+    return is_equal(this, thrown_type, false);
+}
+
+bool
+__array_type_info::can_catch(const __shim_type_info*, void*&) const
+{
+    // We can get here if someone tries to catch an array by reference.
+    //   However if someone tries to throw an array, it immediately gets
+    //   converted to a pointer, which will not convert back to an array
+    //   at the catch clause.  So this can never catch anything.
+    return false;
+}
+
+bool
+__function_type_info::can_catch(const __shim_type_info*, void*&) const
+{
+    // We can get here if someone tries to catch a function by reference.
+    //   However if someone tries to throw a function, it immediately gets
+    //   converted to a pointer, which will not convert back to a function
+    //   at the catch clause.  So this can never catch anything.
+    return false;
+}
+
+// Handles bullet 1
+bool
+__enum_type_info::can_catch(const __shim_type_info* thrown_type,
+                            void*&) const
+{
+    return is_equal(this, thrown_type, false);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+// Handles bullets 1 and 2
+bool
+__class_type_info::can_catch(const __shim_type_info* thrown_type,
+                             void*& adjustedPtr) const
+{
+    // bullet 1
+    if (is_equal(this, thrown_type, false))
+        return true;
+    const __class_type_info* thrown_class_type =
+        dynamic_cast<const __class_type_info*>(thrown_type);
+    if (thrown_class_type == 0)
+        return false;
+    // bullet 2
+    __dynamic_cast_info info = {thrown_class_type, 0, this, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};
+    info.number_of_dst_type = 1;
+    thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
+    if (info.path_dst_ptr_to_static_ptr == public_path)
+    {
+        adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
+        return true;
+    }
+    return false;
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
+void
+__class_type_info::process_found_base_class(__dynamic_cast_info* info,
+                                               void* adjustedPtr,
+                                               int path_below) const
+{
+    if (info->dst_ptr_leading_to_static_ptr == 0)
+    {
+        // First time here
+        info->dst_ptr_leading_to_static_ptr = adjustedPtr;
+        info->path_dst_ptr_to_static_ptr = path_below;
+        info->number_to_static_ptr = 1;
+    }
+    else if (info->dst_ptr_leading_to_static_ptr == adjustedPtr)
+    {
+        // We've been here before.  Update path to "most public"
+        if (info->path_dst_ptr_to_static_ptr == not_public_path)
+            info->path_dst_ptr_to_static_ptr = path_below;
+    }
+    else
+    {
+        // We've detected an ambiguous cast from (thrown_class_type, adjustedPtr)
+        //   to a static_type
+        info->number_to_static_ptr += 1;
+        info->path_dst_ptr_to_static_ptr = not_public_path;
+        info->search_done = true;
+    }
+}
+
+void
+__class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
+                                               void* adjustedPtr,
+                                               int path_below) const
+{
+    if (is_equal(this, info->static_type, false))
+        process_found_base_class(info, adjustedPtr, path_below);
+}
+
+void
+__si_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
+                                                  void* adjustedPtr,
+                                                  int path_below) const
+{
+    if (is_equal(this, info->static_type, false))
+        process_found_base_class(info, adjustedPtr, path_below);
+    else
+        __base_type->has_unambiguous_public_base(info, adjustedPtr, path_below);
+}
+
+void
+__base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
+                                                    void* adjustedPtr,
+                                                    int path_below) const
+{
+    ptrdiff_t offset_to_base = 0;
+    if (adjustedPtr != nullptr)
+    {
+        offset_to_base = __offset_flags >> __offset_shift;
+        if (__offset_flags & __virtual_mask)
+        {
+            const char* vtable = *static_cast<const char*const*>(adjustedPtr);
+            offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
+        }
+    }
+    __base_type->has_unambiguous_public_base(
+            info,
+            static_cast<char*>(adjustedPtr) + offset_to_base,
+            (__offset_flags & __public_mask) ? path_below : not_public_path);
+}
+
+void
+__vmi_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
+                                                   void* adjustedPtr,
+                                                   int path_below) const
+{
+    if (is_equal(this, info->static_type, false))
+        process_found_base_class(info, adjustedPtr, path_below);
+    else
+    {
+        typedef const __base_class_type_info* Iter;
+        const Iter e = __base_info + __base_count;
+        Iter p = __base_info;
+        p->has_unambiguous_public_base(info, adjustedPtr, path_below);
+        if (++p < e)
+        {
+            do
+            {
+                p->has_unambiguous_public_base(info, adjustedPtr, path_below);
+                if (info->search_done)
+                    break;
+            } while (++p < e);
+        }
+    }
+}
+
+// Handles bullet 1 for both pointers and member pointers
+bool
+__pbase_type_info::can_catch(const __shim_type_info* thrown_type,
+                             void*&) const
+{
+    bool use_strcmp = this->__flags & (__incomplete_class_mask |
+                                       __incomplete_mask);
+    if (!use_strcmp) {
+        const __pbase_type_info* thrown_pbase = dynamic_cast<const __pbase_type_info*>(
+                thrown_type);
+        if (!thrown_pbase) return false;
+        use_strcmp = thrown_pbase->__flags & (__incomplete_class_mask |
+                                              __incomplete_mask);
+    }
+    return is_equal(this, thrown_type, use_strcmp);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+// Handles bullets 1, 3 and 4
+// NOTE: It might not be safe to adjust the pointer if it is not not a pointer
+// type. Only adjust the pointer after we know it is safe to do so.
+bool
+__pointer_type_info::can_catch(const __shim_type_info* thrown_type,
+                               void*& adjustedPtr) const
+{
+    // bullet 4
+    if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
+      adjustedPtr = nullptr;
+      return true;
+    }
+
+    // bullet 1
+    if (__pbase_type_info::can_catch(thrown_type, adjustedPtr)) {
+        if (adjustedPtr != NULL)
+            adjustedPtr = *static_cast<void**>(adjustedPtr);
+        return true;
+    }
+    // bullet 3
+    const __pointer_type_info* thrown_pointer_type =
+        dynamic_cast<const __pointer_type_info*>(thrown_type);
+    if (thrown_pointer_type == 0)
+        return false;
+    // Do the dereference adjustment
+    if (adjustedPtr != NULL)
+        adjustedPtr = *static_cast<void**>(adjustedPtr);
+    // bullet 3B and 3C
+    if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
+        return false;
+    if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
+        return false;
+    if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
+        return true;
+    // bullet 3A
+    if (is_equal(__pointee, &typeid(void), false)) {
+        // pointers to functions cannot be converted to void*.
+        // pointers to member functions are not handled here.
+        const __function_type_info* thrown_function =
+            dynamic_cast<const __function_type_info*>(thrown_pointer_type->__pointee);
+        return (thrown_function == nullptr);
+    }
+    // Handle pointer to pointer
+    const __pointer_type_info* nested_pointer_type =
+        dynamic_cast<const __pointer_type_info*>(__pointee);
+    if (nested_pointer_type) {
+        if (~__flags & __const_mask) return false;
+        return nested_pointer_type->can_catch_nested(thrown_pointer_type->__pointee);
+    }
+
+    // Handle pointer to pointer to member
+    const __pointer_to_member_type_info* member_ptr_type =
+        dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
+    if (member_ptr_type) {
+        if (~__flags & __const_mask) return false;
+        return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
+    }
+
+    // Handle pointer to class type
+    const __class_type_info* catch_class_type =
+        dynamic_cast<const __class_type_info*>(__pointee);
+    if (catch_class_type == 0)
+        return false;
+    const __class_type_info* thrown_class_type =
+        dynamic_cast<const __class_type_info*>(thrown_pointer_type->__pointee);
+    if (thrown_class_type == 0)
+        return false;
+    __dynamic_cast_info info = {thrown_class_type, 0, catch_class_type, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};
+    info.number_of_dst_type = 1;
+    thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
+    if (info.path_dst_ptr_to_static_ptr == public_path)
+    {
+        if (adjustedPtr != NULL)
+            adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
+        return true;
+    }
+    return false;
+}
+
+bool __pointer_type_info::can_catch_nested(
+    const __shim_type_info* thrown_type) const
+{
+  const __pointer_type_info* thrown_pointer_type =
+        dynamic_cast<const __pointer_type_info*>(thrown_type);
+    if (thrown_pointer_type == 0)
+        return false;
+    // bullet 3B
+    if (thrown_pointer_type->__flags & ~__flags)
+        return false;
+    if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
+        return true;
+    // If the pointed to types differ then the catch type must be const
+    // qualified.
+    if (~__flags & __const_mask)
+        return false;
+
+    // Handle pointer to pointer
+    const __pointer_type_info* nested_pointer_type =
+        dynamic_cast<const __pointer_type_info*>(__pointee);
+    if (nested_pointer_type) {
+        return nested_pointer_type->can_catch_nested(
+            thrown_pointer_type->__pointee);
+    }
+
+    // Handle pointer to pointer to member
+    const __pointer_to_member_type_info* member_ptr_type =
+        dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
+    if (member_ptr_type) {
+        return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
+    }
+
+    return false;
+}
+
+bool __pointer_to_member_type_info::can_catch(
+    const __shim_type_info* thrown_type, void*& adjustedPtr) const {
+    // bullet 4
+    if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
+      // We assume that the pointer to member representation is the same for
+      // all pointers to data members and for all pointers to member functions.
+      struct X {};
+      if (dynamic_cast<const __function_type_info*>(__pointee)) {
+        static int (X::*const null_ptr_rep)() = nullptr;
+        adjustedPtr = const_cast<int (X::**)()>(&null_ptr_rep);
+      } else {
+        static int X::*const null_ptr_rep = nullptr;
+        adjustedPtr = const_cast<int X::**>(&null_ptr_rep);
+      }
+      return true;
+    }
+
+    // bullet 1
+    if (__pbase_type_info::can_catch(thrown_type, adjustedPtr))
+        return true;
+
+    const __pointer_to_member_type_info* thrown_pointer_type =
+        dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
+    if (thrown_pointer_type == 0)
+        return false;
+    if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
+        return false;
+    if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
+        return false;
+    if (!is_equal(__pointee, thrown_pointer_type->__pointee, false))
+        return false;
+    if (is_equal(__context, thrown_pointer_type->__context, false))
+        return true;
+
+    // [except.handle] does not allow the pointer-to-member conversions mentioned
+    // in [mem.conv] to take place. For this reason we don't check Derived->Base
+    // for Derived->Base conversions.
+
+    return false;
+}
+
+bool __pointer_to_member_type_info::can_catch_nested(
+    const __shim_type_info* thrown_type) const
+{
+    const __pointer_to_member_type_info* thrown_member_ptr_type =
+        dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
+    if (thrown_member_ptr_type == 0)
+        return false;
+    if (~__flags & thrown_member_ptr_type->__flags)
+        return false;
+    if (!is_equal(__pointee, thrown_member_ptr_type->__pointee, false))
+        return false;
+    if (!is_equal(__context, thrown_member_ptr_type->__context, false))
+        return false;
+    return true;
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+// __dynamic_cast
+
+// static_ptr: pointer to an object of type static_type; nonnull, and since the
+//   object is polymorphic, *(void**)static_ptr is a virtual table pointer.
+//   static_ptr is &v in the expression dynamic_cast<T>(v).
+// static_type: static type of the object pointed to by static_ptr.
+// dst_type: destination type of the cast (the "T" in "dynamic_cast<T>(v)").
+// src2dst_offset: a static hint about the location of the
+//                 source subobject with respect to the complete object;
+//                 special negative values are:
+//                     -1: no hint
+//                     -2: static_type is not a public base of dst_type
+//                     -3: static_type is a multiple public base type but never a
+//                         virtual base type
+//                 otherwise, the static_type type is a unique public nonvirtual
+//                 base type of dst_type at offset src2dst_offset from the
+//                 origin of dst_type.
+//
+// (dynamic_ptr, dynamic_type) are the run time type of the complete object
+// referred to by static_ptr and a pointer to it.  These can be found from
+// static_ptr for polymorphic types.
+// static_type is guaranteed to be a polymorphic type.
+//
+// (dynamic_ptr, dynamic_type) is the root of a DAG that grows upward.  Each
+// node of the tree represents a base class/object of its parent (or parents) below.
+// Each node is uniquely represented by a pointer to the object, and a pointer
+// to a type_info - its type.  Different nodes may have the same pointer and
+// different nodes may have the same type.  But only one node has a specific
+// (pointer-value, type) pair.  In C++ two objects of the same type can not
+// share the same address.
+//
+// There are two flavors of nodes which have the type dst_type:
+//    1.  Those that are derived from (below) (static_ptr, static_type).
+//    2.  Those that are not derived from (below) (static_ptr, static_type).
+//
+// Invariants of the DAG:
+//
+// There is at least one path from the root (dynamic_ptr, dynamic_type) to
+// the node (static_ptr, static_type).  This path may or may not be public.
+// There may be more than one such path (some public some not).  Such a path may
+// or may not go through a node having type dst_type.
+//
+// No node of type T appears above a node of the same type.  That means that
+// there is only one node with dynamic_type.  And if dynamic_type == dst_type,
+// then there is only one dst_type in the DAG.
+//
+// No node of type dst_type appears above a node of type static_type.  Such
+// DAG's are possible in C++, but the compiler computes those dynamic_casts at
+// compile time, and only calls __dynamic_cast when dst_type lies below
+// static_type in the DAG.
+//
+// dst_type != static_type:  The compiler computes the dynamic_cast in this case too.
+// dynamic_type != static_type:  The compiler computes the dynamic_cast in this case too.
+//
+// Returns:
+//
+// If there is exactly one dst_type of flavor 1, and
+//    If there is a public path from that dst_type to (static_ptr, static_type), or
+//    If there are 0 dst_types of flavor 2, and there is a public path from
+//        (dynamic_ptr, dynamic_type) to (static_ptr, static_type) and a public
+//        path from (dynamic_ptr, dynamic_type) to the one dst_type, then return
+//        a pointer to that dst_type.
+// Else if there are 0 dst_types of flavor 1 and exactly 1 dst_type of flavor 2, and
+//    if there is a public path from (dynamic_ptr, dynamic_type) to
+//    (static_ptr, static_type) and a public path from (dynamic_ptr, dynamic_type)
+//    to the one dst_type, then return a pointer to that one dst_type.
+// Else return nullptr.
+//
+// If dynamic_type == dst_type, then the above algorithm collapses to the
+// following cheaper algorithm:
+//
+// If there is a public path from (dynamic_ptr, dynamic_type) to
+//    (static_ptr, static_type), then return dynamic_ptr.
+// Else return nullptr.
+
+extern "C" _LIBCXXABI_FUNC_VIS void *
+__dynamic_cast(const void *static_ptr, const __class_type_info *static_type,
+               const __class_type_info *dst_type,
+               std::ptrdiff_t src2dst_offset) {
+    // Possible future optimization:  Take advantage of src2dst_offset
+
+    // Get (dynamic_ptr, dynamic_type) from static_ptr
+    void **vtable = *static_cast<void ** const *>(static_ptr);
+    ptrdiff_t offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
+    const void* dynamic_ptr = static_cast<const char*>(static_ptr) + offset_to_derived;
+    const __class_type_info* dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
+
+    // Initialize answer to nullptr.  This will be changed from the search
+    //    results if a non-null answer is found.  Regardless, this is what will
+    //    be returned.
+    const void* dst_ptr = 0;
+    // Initialize info struct for this search.
+    __dynamic_cast_info info = {dst_type, static_ptr, static_type, src2dst_offset, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};
+
+    // Find out if we can use a giant short cut in the search
+    if (is_equal(dynamic_type, dst_type, false))
+    {
+        // Using giant short cut.  Add that information to info.
+        info.number_of_dst_type = 1;
+        // Do the  search
+        dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, false);
+#ifdef _LIBCXX_DYNAMIC_FALLBACK
+        // The following if should always be false because we should definitely
+        //   find (static_ptr, static_type), either on a public or private path
+        if (info.path_dst_ptr_to_static_ptr == unknown)
+        {
+            // We get here only if there is some kind of visibility problem
+            //   in client code.
+            syslog(LOG_ERR, "dynamic_cast error 1: Both of the following type_info's "
+                    "should have public visibility. At least one of them is hidden. %s"
+                    ", %s.\n", static_type->name(), dynamic_type->name());
+            // Redo the search comparing type_info's using strcmp
+            info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
+            info.number_of_dst_type = 1;
+            dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, true);
+        }
+#endif  // _LIBCXX_DYNAMIC_FALLBACK
+        // Query the search.
+        if (info.path_dst_ptr_to_static_ptr == public_path)
+            dst_ptr = dynamic_ptr;
+    }
+    else
+    {
+        // Not using giant short cut.  Do the search
+        dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, false);
+ #ifdef _LIBCXX_DYNAMIC_FALLBACK
+        // The following if should always be false because we should definitely
+        //   find (static_ptr, static_type), either on a public or private path
+        if (info.path_dst_ptr_to_static_ptr == unknown &&
+            info.path_dynamic_ptr_to_static_ptr == unknown)
+        {
+            syslog(LOG_ERR, "dynamic_cast error 2: One or more of the following type_info's "
+                            "has hidden visibility or is defined in more than one translation "
+                            "unit. They should all have public visibility. "
+                            "%s, %s, %s.\n", static_type->name(), dynamic_type->name(),
+                    dst_type->name());
+            // Redo the search comparing type_info's using strcmp
+            info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
+            dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, true);
+        }
+#endif  // _LIBCXX_DYNAMIC_FALLBACK
+        // Query the search.
+        switch (info.number_to_static_ptr)
+        {
+        case 0:
+            if (info.number_to_dst_ptr == 1 &&
+                    info.path_dynamic_ptr_to_static_ptr == public_path &&
+                    info.path_dynamic_ptr_to_dst_ptr == public_path)
+                dst_ptr = info.dst_ptr_not_leading_to_static_ptr;
+            break;
+        case 1:
+            if (info.path_dst_ptr_to_static_ptr == public_path ||
+                   (
+                       info.number_to_dst_ptr == 0 &&
+                       info.path_dynamic_ptr_to_static_ptr == public_path &&
+                       info.path_dynamic_ptr_to_dst_ptr == public_path
+                   )
+               )
+                dst_ptr = info.dst_ptr_leading_to_static_ptr;
+            break;
+        }
+    }
+    return const_cast<void*>(dst_ptr);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
+// Call this function when you hit a static_type which is a base (above) a dst_type.
+// Let caller know you hit a static_type.  But only start recording details if
+// this is (static_ptr, static_type) -- the node we are casting from.
+// If this is (static_ptr, static_type)
+//   Record the path (public or not) from the dst_type to here.  There may be
+//   multiple paths from the same dst_type to here, record the "most public" one.
+//   Record the dst_ptr as pointing to (static_ptr, static_type).
+//   If more than one (dst_ptr, dst_type) points to (static_ptr, static_type),
+//   then mark this dyanmic_cast as ambiguous and stop the search.
+void
+__class_type_info::process_static_type_above_dst(__dynamic_cast_info* info,
+                                                 const void* dst_ptr,
+                                                 const void* current_ptr,
+                                                 int path_below) const
+{
+    // Record that we found a static_type
+    info->found_any_static_type = true;
+    if (current_ptr == info->static_ptr)
+    {
+        // Record that we found (static_ptr, static_type)
+        info->found_our_static_ptr = true;
+        if (info->dst_ptr_leading_to_static_ptr == 0)
+        {
+            // First time here
+            info->dst_ptr_leading_to_static_ptr = dst_ptr;
+            info->path_dst_ptr_to_static_ptr = path_below;
+            info->number_to_static_ptr = 1;
+            // If there is only one dst_type in the entire tree and the path from
+            //    there to here is public then we are done!
+            if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
+                info->search_done = true;
+        }
+        else if (info->dst_ptr_leading_to_static_ptr == dst_ptr)
+        {
+            // We've been here before.  Update path to "most public"
+            if (info->path_dst_ptr_to_static_ptr == not_public_path)
+                info->path_dst_ptr_to_static_ptr = path_below;
+            // If there is only one dst_type in the entire tree and the path from
+            //    there to here is public then we are done!
+            if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
+                info->search_done = true;
+        }
+        else
+        {
+            // We've detected an ambiguous cast from (static_ptr, static_type)
+            //   to a dst_type
+            info->number_to_static_ptr += 1;
+            info->search_done = true;
+        }
+    }
+}
+
+// Call this function when you hit a static_type which is not a base (above) a dst_type.
+// If this is (static_ptr, static_type)
+//   Record the path (public or not) from (dynamic_ptr, dynamic_type) to here.  There may be
+//   multiple paths from (dynamic_ptr, dynamic_type) to here, record the "most public" one.
+void
+__class_type_info::process_static_type_below_dst(__dynamic_cast_info* info,
+                                                 const void* current_ptr,
+                                                 int path_below) const
+{
+    if (current_ptr == info->static_ptr)
+    {
+        // Record the most public path from (dynamic_ptr, dynamic_type) to
+        //                                  (static_ptr, static_type)
+        if (info->path_dynamic_ptr_to_static_ptr != public_path)
+            info->path_dynamic_ptr_to_static_ptr = path_below;
+    }
+}
+
+// Call this function when searching below a dst_type node.  This function searches
+// for a path to (static_ptr, static_type) and for paths to one or more dst_type nodes.
+// If it finds a static_type node, there is no need to further search base classes
+// above.
+// If it finds a dst_type node it should search base classes using search_above_dst
+// to find out if this dst_type points to (static_ptr, static_type) or not.
+// Either way, the dst_type is recorded as one of two "flavors":  one that does
+// or does not point to (static_ptr, static_type).
+// If this is neither a static_type nor a dst_type node, continue searching
+// base classes above.
+// All the hoopla surrounding the search code is doing nothing but looking for
+// excuses to stop the search prematurely (break out of the for-loop).  That is,
+// the algorithm below is simply an optimization of this:
+// void
+// __vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
+//                                         const void* current_ptr,
+//                                         int path_below) const
+// {
+//     typedef const __base_class_type_info* Iter;
+//     if (this == info->static_type)
+//         process_static_type_below_dst(info, current_ptr, path_below);
+//     else if (this == info->dst_type)
+//     {
+//         // Record the most public access path that got us here
+//         if (info->path_dynamic_ptr_to_dst_ptr != public_path)
+//             info->path_dynamic_ptr_to_dst_ptr = path_below;
+//         bool does_dst_type_point_to_our_static_type = false;
+//         for (Iter p = __base_info, e= __base_info + __base_count; p < e; ++p)
+//         {
+//             p->search_above_dst(info, current_ptr, current_ptr, public_path);
+//             if (info->found_our_static_ptr)
+//                 does_dst_type_point_to_our_static_type = true;
+//             // break out early here if you can detect it doesn't matter if you do
+//         }
+//         if (!does_dst_type_point_to_our_static_type)
+//         {
+//             // We found a dst_type that doesn't point to (static_ptr, static_type)
+//             // So record the address of this dst_ptr and increment the
+//             // count of the number of such dst_types found in the tree.
+//             info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+//             info->number_to_dst_ptr += 1;
+//         }
+//     }
+//     else
+//     {
+//         // This is not a static_type and not a dst_type.
+//         for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
+//         {
+//             p->search_below_dst(info, current_ptr, public_path);
+//             // break out early here if you can detect it doesn't matter if you do
+//         }
+//     }
+// }
+void
+__vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
+                                        const void* current_ptr,
+                                        int path_below,
+                                        bool use_strcmp) const
+{
+    typedef const __base_class_type_info* Iter;
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_below_dst(info, current_ptr, path_below);
+    else if (is_equal(this, info->dst_type, use_strcmp))
+    {
+        // We've been here before if we've recorded current_ptr in one of these
+        //   two places:
+        if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
+            current_ptr == info->dst_ptr_not_leading_to_static_ptr)
+        {
+            // We've seen this node before, and therefore have already searched
+            // its base classes above.
+            //  Update path to here that is "most public".
+            if (path_below == public_path)
+                info->path_dynamic_ptr_to_dst_ptr = public_path;
+        }
+        else  // We have haven't been here before
+        {
+            // Record the access path that got us here
+            //   If there is more than one dst_type this path doesn't matter.
+            info->path_dynamic_ptr_to_dst_ptr = path_below;
+            bool does_dst_type_point_to_our_static_type = false;
+            // Only search above here if dst_type derives from static_type, or
+            //    if it is unknown if dst_type derives from static_type.
+            if (info->is_dst_type_derived_from_static_type != no)
+            {
+                // Set up flags to record results from all base classes
+                bool is_dst_type_derived_from_static_type = false;
+
+                // We've found a dst_type with a potentially public path to here.
+                // We have to assume the path is public because it may become
+                //   public later (if we get back to here with a public path).
+                // We can stop looking above if:
+                //    1.  We've found a public path to (static_ptr, static_type).
+                //    2.  We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
+                //        This is detected at the (static_ptr, static_type).
+                //    3.  We can prove that there is no public path to (static_ptr, static_type)
+                //        above here.
+                const Iter e = __base_info + __base_count;
+                for (Iter p = __base_info; p < e; ++p)
+                {
+                    // Zero out found flags
+                    info->found_our_static_ptr = false;
+                    info->found_any_static_type = false;
+                    p->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
+                    if (info->search_done)
+                        break;
+                    if (info->found_any_static_type)
+                    {
+                        is_dst_type_derived_from_static_type = true;
+                        if (info->found_our_static_ptr)
+                        {
+                            does_dst_type_point_to_our_static_type = true;
+                            // If we found what we're looking for, stop looking above.
+                            if (info->path_dst_ptr_to_static_ptr == public_path)
+                                break;
+                            // We found a private path to (static_ptr, static_type)
+                            //   If there is no diamond then there is only one path
+                            //   to (static_ptr, static_type) and we just found it.
+                            if (!(__flags & __diamond_shaped_mask))
+                                break;
+                        }
+                        else
+                        {
+                            // If we found a static_type that isn't the one we're looking
+                            //    for, and if there are no repeated types above here,
+                            //    then stop looking.
+                            if (!(__flags & __non_diamond_repeat_mask))
+                                break;
+                        }
+                    }
+                }
+                // If we found no static_type,s then dst_type doesn't derive
+                //   from static_type, else it does.  Record this result so that
+                //   next time we hit a dst_type we will know not to search above
+                //   it if it doesn't derive from static_type.
+                if (is_dst_type_derived_from_static_type)
+                    info->is_dst_type_derived_from_static_type = yes;
+                else
+                    info->is_dst_type_derived_from_static_type = no;
+              }
+              if (!does_dst_type_point_to_our_static_type)
+              {
+                  // We found a dst_type that doesn't point to (static_ptr, static_type)
+                  // So record the address of this dst_ptr and increment the
+                  // count of the number of such dst_types found in the tree.
+                  info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+                  info->number_to_dst_ptr += 1;
+                  // If there exists another dst with a private path to
+                  //    (static_ptr, static_type), then the cast from
+                  //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous,
+                  //      so stop search.
+                  if (info->number_to_static_ptr == 1 &&
+                          info->path_dst_ptr_to_static_ptr == not_public_path)
+                      info->search_done = true;
+              }
+        }
+    }
+    else
+    {
+        // This is not a static_type and not a dst_type.
+        const Iter e = __base_info + __base_count;
+        Iter p = __base_info;
+        p->search_below_dst(info, current_ptr, path_below, use_strcmp);
+        if (++p < e)
+        {
+            if ((__flags & __diamond_shaped_mask) || info->number_to_static_ptr == 1)
+            {
+                // If there are multiple paths to a base above from here, or if
+                //    a dst_type pointing to (static_ptr, static_type) has been found,
+                //    then there is no way to break out of this loop early unless
+                //    something below detects the search is done.
+                do
+                {
+                    if (info->search_done)
+                        break;
+                    p->search_below_dst(info, current_ptr, path_below, use_strcmp);
+                } while (++p < e);
+            }
+            else if (__flags & __non_diamond_repeat_mask)
+            {
+                // There are not multiple paths to any base class from here and a
+                //   dst_type pointing to (static_ptr, static_type) has not yet been
+                //   found.
+                do
+                {
+                    if (info->search_done)
+                        break;
+                    // If we just found a dst_type with a public path to (static_ptr, static_type),
+                    //    then the only reason to continue the search is to make sure
+                    //    no other dst_type points to (static_ptr, static_type).
+                    //    If !diamond, then we don't need to search here.
+                    if (info->number_to_static_ptr == 1 &&
+                              info->path_dst_ptr_to_static_ptr == public_path)
+                        break;
+                    p->search_below_dst(info, current_ptr, path_below, use_strcmp);
+                } while (++p < e);
+            }
+            else
+            {
+                // There are no repeated types above this node.
+                // There are no nodes with multiple parents above this node.
+                // no dst_type has been found to (static_ptr, static_type)
+                do
+                {
+                    if (info->search_done)
+                        break;
+                    // If we just found a dst_type with a public path to (static_ptr, static_type),
+                    //    then the only reason to continue the search is to make sure sure
+                    //    no other dst_type points to (static_ptr, static_type).
+                    //    If !diamond, then we don't need to search here.
+                    // if we just found a dst_type with a private path to (static_ptr, static_type),
+                    //    then we're only looking for a public path to (static_ptr, static_type)
+                    //    and to check for other dst_types.
+                    //    If !diamond & !repeat, then there is not a pointer to (static_ptr, static_type)
+                    //    and not a dst_type under here.
+                    if (info->number_to_static_ptr == 1)
+                        break;
+                    p->search_below_dst(info, current_ptr, path_below, use_strcmp);
+                } while (++p < e);
+            }
+        }
+    }
+}
+
+// This is the same algorithm as __vmi_class_type_info::search_below_dst but
+//   simplified to the case that there is only a single base class.
+void
+__si_class_type_info::search_below_dst(__dynamic_cast_info* info,
+                                       const void* current_ptr,
+                                       int path_below,
+                                       bool use_strcmp) const
+{
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_below_dst(info, current_ptr, path_below);
+    else if (is_equal(this, info->dst_type, use_strcmp))
+    {
+        // We've been here before if we've recorded current_ptr in one of these
+        //   two places:
+        if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
+            current_ptr == info->dst_ptr_not_leading_to_static_ptr)
+        {
+            // We've seen this node before, and therefore have already searched
+            // its base classes above.
+            //  Update path to here that is "most public".
+            if (path_below == public_path)
+                info->path_dynamic_ptr_to_dst_ptr = public_path;
+        }
+        else  // We have haven't been here before
+        {
+            // Record the access path that got us here
+            //   If there is more than one dst_type this path doesn't matter.
+            info->path_dynamic_ptr_to_dst_ptr = path_below;
+            bool does_dst_type_point_to_our_static_type = false;
+            // Only search above here if dst_type derives from static_type, or
+            //    if it is unknown if dst_type derives from static_type.
+            if (info->is_dst_type_derived_from_static_type != no)
+            {
+                // Set up flags to record results from all base classes
+                bool is_dst_type_derived_from_static_type = false;
+                // Zero out found flags
+                info->found_our_static_ptr = false;
+                info->found_any_static_type = false;
+                __base_type->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
+                if (info->found_any_static_type)
+                {
+                    is_dst_type_derived_from_static_type = true;
+                    if (info->found_our_static_ptr)
+                        does_dst_type_point_to_our_static_type = true;
+                }
+                // If we found no static_type,s then dst_type doesn't derive
+                //   from static_type, else it does.  Record this result so that
+                //   next time we hit a dst_type we will know not to search above
+                //   it if it doesn't derive from static_type.
+                if (is_dst_type_derived_from_static_type)
+                    info->is_dst_type_derived_from_static_type = yes;
+                else
+                    info->is_dst_type_derived_from_static_type = no;
+            }
+            if (!does_dst_type_point_to_our_static_type)
+            {
+                // We found a dst_type that doesn't point to (static_ptr, static_type)
+                // So record the address of this dst_ptr and increment the
+                // count of the number of such dst_types found in the tree.
+                info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+                info->number_to_dst_ptr += 1;
+                // If there exists another dst with a private path to
+                //    (static_ptr, static_type), then the cast from
+                //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
+                if (info->number_to_static_ptr == 1 &&
+                        info->path_dst_ptr_to_static_ptr == not_public_path)
+                    info->search_done = true;
+            }
+        }
+    }
+    else
+    {
+        // This is not a static_type and not a dst_type
+        __base_type->search_below_dst(info, current_ptr, path_below, use_strcmp);
+    }
+}
+
+// This is the same algorithm as __vmi_class_type_info::search_below_dst but
+//   simplified to the case that there is no base class.
+void
+__class_type_info::search_below_dst(__dynamic_cast_info* info,
+                                    const void* current_ptr,
+                                    int path_below,
+                                    bool use_strcmp) const
+{
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_below_dst(info, current_ptr, path_below);
+    else if (is_equal(this, info->dst_type, use_strcmp))
+    {
+        // We've been here before if we've recorded current_ptr in one of these
+        //   two places:
+        if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
+            current_ptr == info->dst_ptr_not_leading_to_static_ptr)
+        {
+            // We've seen this node before, and therefore have already searched
+            // its base classes above.
+            //  Update path to here that is "most public".
+            if (path_below == public_path)
+                info->path_dynamic_ptr_to_dst_ptr = public_path;
+        }
+        else  // We have haven't been here before
+        {
+            // Record the access path that got us here
+            //   If there is more than one dst_type this path doesn't matter.
+            info->path_dynamic_ptr_to_dst_ptr = path_below;
+            // We found a dst_type that doesn't point to (static_ptr, static_type)
+            // So record the address of this dst_ptr and increment the
+            // count of the number of such dst_types found in the tree.
+            info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+            info->number_to_dst_ptr += 1;
+            // If there exists another dst with a private path to
+            //    (static_ptr, static_type), then the cast from
+            //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
+            if (info->number_to_static_ptr == 1 &&
+                    info->path_dst_ptr_to_static_ptr == not_public_path)
+                info->search_done = true;
+            // We found that dst_type does not derive from static_type
+            info->is_dst_type_derived_from_static_type = no;
+        }
+    }
+}
+
+// Call this function when searching above a dst_type node.  This function searches
+// for a public path to (static_ptr, static_type).
+// This function is guaranteed not to find a node of type dst_type.
+// Theoretically this is a very simple function which just stops if it finds a
+// static_type node:  All the hoopla surrounding the search code is doing
+// nothing but looking for excuses to stop the search prematurely (break out of
+// the for-loop).  That is, the algorithm below is simply an optimization of this:
+// void
+// __vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
+//                                         const void* dst_ptr,
+//                                         const void* current_ptr,
+//                                         int path_below) const
+// {
+//     if (this == info->static_type)
+//         process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
+//     else
+//     {
+//         typedef const __base_class_type_info* Iter;
+//         // This is not a static_type and not a dst_type
+//         for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
+//         {
+//             p->search_above_dst(info, dst_ptr, current_ptr, public_path);
+//             // break out early here if you can detect it doesn't matter if you do
+//         }
+//     }
+// }
+void
+__vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
+                                        const void* dst_ptr,
+                                        const void* current_ptr,
+                                        int path_below,
+                                        bool use_strcmp) const
+{
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
+    else
+    {
+        typedef const __base_class_type_info* Iter;
+        // This is not a static_type and not a dst_type
+        // Save flags so they can be restored when returning to nodes below.
+        bool found_our_static_ptr = info->found_our_static_ptr;
+        bool found_any_static_type = info->found_any_static_type;
+        // We've found a dst_type below with a path to here.  If the path
+        //    to here is not public, there may be another path to here that
+        //    is public.  So we have to assume that the path to here is public.
+        //  We can stop looking above if:
+        //    1.  We've found a public path to (static_ptr, static_type).
+        //    2.  We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
+        //        This is detected at the (static_ptr, static_type).
+        //    3.  We can prove that there is no public path to (static_ptr, static_type)
+        //        above here.
+        const Iter e = __base_info + __base_count;
+        Iter p = __base_info;
+        // Zero out found flags
+        info->found_our_static_ptr = false;
+        info->found_any_static_type = false;
+        p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
+        found_our_static_ptr |= info->found_our_static_ptr;
+        found_any_static_type |= info->found_any_static_type;
+        if (++p < e)
+        {
+            do
+            {
+                if (info->search_done)
+                    break;
+                if (info->found_our_static_ptr)
+                {
+                    // If we found what we're looking for, stop looking above.
+                    if (info->path_dst_ptr_to_static_ptr == public_path)
+                        break;
+                    // We found a private path to (static_ptr, static_type)
+                    //   If there is no diamond then there is only one path
+                    //   to (static_ptr, static_type) from here and we just found it.
+                    if (!(__flags & __diamond_shaped_mask))
+                        break;
+                }
+                else if (info->found_any_static_type)
+                {
+                    // If we found a static_type that isn't the one we're looking
+                    //    for, and if there are no repeated types above here,
+                    //    then stop looking.
+                    if (!(__flags & __non_diamond_repeat_mask))
+                        break;
+                }
+                // Zero out found flags
+                info->found_our_static_ptr = false;
+                info->found_any_static_type = false;
+                p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
+                found_our_static_ptr |= info->found_our_static_ptr;
+                found_any_static_type |= info->found_any_static_type;
+            } while (++p < e);
+        }
+        // Restore flags
+        info->found_our_static_ptr = found_our_static_ptr;
+        info->found_any_static_type = found_any_static_type;
+    }
+}
+
+// This is the same algorithm as __vmi_class_type_info::search_above_dst but
+//   simplified to the case that there is only a single base class.
+void
+__si_class_type_info::search_above_dst(__dynamic_cast_info* info,
+                                       const void* dst_ptr,
+                                       const void* current_ptr,
+                                       int path_below,
+                                       bool use_strcmp) const
+{
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
+    else
+        __base_type->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
+}
+
+// This is the same algorithm as __vmi_class_type_info::search_above_dst but
+//   simplified to the case that there is no base class.
+void
+__class_type_info::search_above_dst(__dynamic_cast_info* info,
+                                    const void* dst_ptr,
+                                    const void* current_ptr,
+                                    int path_below,
+                                    bool use_strcmp) const
+{
+    if (is_equal(this, info->static_type, use_strcmp))
+        process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
+}
+
+// The search functions for __base_class_type_info are simply convenience
+//   functions for adjusting the current_ptr and path_below as the search is
+//   passed up to the base class node.
+
+void
+__base_class_type_info::search_above_dst(__dynamic_cast_info* info,
+                                         const void* dst_ptr,
+                                         const void* current_ptr,
+                                         int path_below,
+                                         bool use_strcmp) const
+{
+    ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
+    if (__offset_flags & __virtual_mask)
+    {
+        const char* vtable = *static_cast<const char*const*>(current_ptr);
+        offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
+    }
+    __base_type->search_above_dst(info, dst_ptr,
+                                  static_cast<const char*>(current_ptr) + offset_to_base,
+                                  (__offset_flags & __public_mask) ?
+                                      path_below :
+                                      not_public_path,
+                                  use_strcmp);
+}
+
+void
+__base_class_type_info::search_below_dst(__dynamic_cast_info* info,
+                                         const void* current_ptr,
+                                         int path_below,
+                                         bool use_strcmp) const
+{
+    ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
+    if (__offset_flags & __virtual_mask)
+    {
+        const char* vtable = *static_cast<const char*const*>(current_ptr);
+        offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
+    }
+    __base_type->search_below_dst(info,
+                                  static_cast<const char*>(current_ptr) + offset_to_base,
+                                  (__offset_flags & __public_mask) ?
+                                      path_below :
+                                      not_public_path,
+                                  use_strcmp);
+}
+
+}  // __cxxabiv1
diff --git a/lib/libcxxabi/src/private_typeinfo.h b/lib/libcxxabi/src/private_typeinfo.h
new file mode 100644
index 0000000000..cf680d6b1f
--- /dev/null
+++ b/lib/libcxxabi/src/private_typeinfo.h
@@ -0,0 +1,251 @@
+//===------------------------ private_typeinfo.h --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __PRIVATE_TYPEINFO_H_
+#define __PRIVATE_TYPEINFO_H_
+
+#include "__cxxabi_config.h"
+
+#include <typeinfo>
+#include <stddef.h>
+
+namespace __cxxabiv1 {
+
+class _LIBCXXABI_TYPE_VIS __shim_type_info : public std::type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__shim_type_info();
+
+  _LIBCXXABI_HIDDEN virtual void noop1() const;
+  _LIBCXXABI_HIDDEN virtual void noop2() const;
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *thrown_type,
+                                           void *&adjustedPtr) const = 0;
+};
+
+class _LIBCXXABI_TYPE_VIS __fundamental_type_info : public __shim_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__fundamental_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __array_type_info : public __shim_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__array_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __function_type_info : public __shim_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__function_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __enum_type_info : public __shim_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__enum_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+};
+
+enum
+{
+    unknown = 0,
+    public_path,
+    not_public_path,
+    yes,
+    no
+};
+
+class _LIBCXXABI_TYPE_VIS __class_type_info;
+
+struct _LIBCXXABI_HIDDEN __dynamic_cast_info
+{
+// const data supplied to the search:
+
+    const __class_type_info* dst_type;
+    const void* static_ptr;
+    const __class_type_info* static_type;
+    ptrdiff_t src2dst_offset;
+
+// Data that represents the answer:
+
+    // pointer to a dst_type which has (static_ptr, static_type) above it
+    const void* dst_ptr_leading_to_static_ptr;
+    // pointer to a dst_type which does not have (static_ptr, static_type) above it
+    const void* dst_ptr_not_leading_to_static_ptr;
+
+    // The following three paths are either unknown, public_path or not_public_path.
+    // access of path from dst_ptr_leading_to_static_ptr to (static_ptr, static_type)
+    int path_dst_ptr_to_static_ptr;
+    // access of path from (dynamic_ptr, dynamic_type) to (static_ptr, static_type)
+    //    when there is no dst_type along the path
+    int path_dynamic_ptr_to_static_ptr;
+    // access of path from (dynamic_ptr, dynamic_type) to dst_type
+    //    (not used if there is a (static_ptr, static_type) above a dst_type).
+    int path_dynamic_ptr_to_dst_ptr;
+
+    // Number of dst_types below (static_ptr, static_type)
+    int number_to_static_ptr;
+    // Number of dst_types not below (static_ptr, static_type)
+    int number_to_dst_ptr;
+
+// Data that helps stop the search before the entire tree is searched:
+
+    // is_dst_type_derived_from_static_type is either unknown, yes or no.
+    int is_dst_type_derived_from_static_type;
+    // Number of dst_type in tree.  If 0, then that means unknown.
+    int number_of_dst_type;
+    // communicates to a dst_type node that (static_ptr, static_type) was found
+    //    above it.
+    bool found_our_static_ptr;
+    // communicates to a dst_type node that a static_type was found
+    //    above it, but it wasn't (static_ptr, static_type)
+    bool found_any_static_type;
+    // Set whenever a search can be stopped
+    bool search_done;
+};
+
+// Has no base class
+class _LIBCXXABI_TYPE_VIS __class_type_info : public __shim_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__class_type_info();
+
+  _LIBCXXABI_HIDDEN void process_static_type_above_dst(__dynamic_cast_info *,
+                                                       const void *,
+                                                       const void *, int) const;
+  _LIBCXXABI_HIDDEN void process_static_type_below_dst(__dynamic_cast_info *,
+                                                       const void *, int) const;
+  _LIBCXXABI_HIDDEN void process_found_base_class(__dynamic_cast_info *, void *,
+                                                  int) const;
+  _LIBCXXABI_HIDDEN virtual void search_above_dst(__dynamic_cast_info *,
+                                                  const void *, const void *,
+                                                  int, bool) const;
+  _LIBCXXABI_HIDDEN virtual void
+  search_below_dst(__dynamic_cast_info *, const void *, int, bool) const;
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+  _LIBCXXABI_HIDDEN virtual void
+  has_unambiguous_public_base(__dynamic_cast_info *, void *, int) const;
+};
+
+// Has one non-virtual public base class at offset zero
+class _LIBCXXABI_TYPE_VIS __si_class_type_info : public __class_type_info {
+public:
+  const __class_type_info *__base_type;
+
+  _LIBCXXABI_HIDDEN virtual ~__si_class_type_info();
+
+  _LIBCXXABI_HIDDEN virtual void search_above_dst(__dynamic_cast_info *,
+                                                  const void *, const void *,
+                                                  int, bool) const;
+  _LIBCXXABI_HIDDEN virtual void
+  search_below_dst(__dynamic_cast_info *, const void *, int, bool) const;
+  _LIBCXXABI_HIDDEN virtual void
+  has_unambiguous_public_base(__dynamic_cast_info *, void *, int) const;
+};
+
+struct _LIBCXXABI_HIDDEN __base_class_type_info
+{
+public:
+    const __class_type_info* __base_type;
+    long __offset_flags;
+
+    enum __offset_flags_masks
+    {
+        __virtual_mask = 0x1,
+        __public_mask  = 0x2, // base is public
+        __offset_shift = 8
+    };
+
+    void search_above_dst(__dynamic_cast_info*, const void*, const void*, int, bool) const;
+    void search_below_dst(__dynamic_cast_info*, const void*, int, bool) const;
+    void has_unambiguous_public_base(__dynamic_cast_info*, void*, int) const;
+};
+
+// Has one or more base classes
+class _LIBCXXABI_TYPE_VIS __vmi_class_type_info : public __class_type_info {
+public:
+  unsigned int __flags;
+  unsigned int __base_count;
+  __base_class_type_info __base_info[1];
+
+  enum __flags_masks {
+    __non_diamond_repeat_mask = 0x1, // has two or more distinct base class
+                                     //    objects of the same type
+    __diamond_shaped_mask = 0x2      // has base class object with two or
+                                     //    more derived objects
+  };
+
+  _LIBCXXABI_HIDDEN virtual ~__vmi_class_type_info();
+
+  _LIBCXXABI_HIDDEN virtual void search_above_dst(__dynamic_cast_info *,
+                                                  const void *, const void *,
+                                                  int, bool) const;
+  _LIBCXXABI_HIDDEN virtual void
+  search_below_dst(__dynamic_cast_info *, const void *, int, bool) const;
+  _LIBCXXABI_HIDDEN virtual void
+  has_unambiguous_public_base(__dynamic_cast_info *, void *, int) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __pbase_type_info : public __shim_type_info {
+public:
+  unsigned int __flags;
+  const __shim_type_info *__pointee;
+
+  enum __masks {
+    __const_mask = 0x1,
+    __volatile_mask = 0x2,
+    __restrict_mask = 0x4,
+    __incomplete_mask = 0x8,
+    __incomplete_class_mask = 0x10,
+    __transaction_safe_mask = 0x20,
+    // This implements the following proposal from cxx-abi-dev (not yet part of
+    // the ABI document):
+    //
+    //   http://sourcerytools.com/pipermail/cxx-abi-dev/2016-October/002986.html
+    //
+    // This is necessary for support of http://wg21.link/p0012, which permits
+    // throwing noexcept function and member function pointers and catching
+    // them as non-noexcept pointers.
+    __noexcept_mask = 0x40,
+
+    // Flags that cannot be removed by a standard conversion.
+    __no_remove_flags_mask = __const_mask | __volatile_mask | __restrict_mask,
+    // Flags that cannot be added by a standard conversion.
+    __no_add_flags_mask = __transaction_safe_mask | __noexcept_mask
+  };
+
+  _LIBCXXABI_HIDDEN virtual ~__pbase_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __pointer_type_info : public __pbase_type_info {
+public:
+  _LIBCXXABI_HIDDEN virtual ~__pointer_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+  _LIBCXXABI_HIDDEN bool can_catch_nested(const __shim_type_info *) const;
+};
+
+class _LIBCXXABI_TYPE_VIS __pointer_to_member_type_info
+    : public __pbase_type_info {
+public:
+  const __class_type_info *__context;
+
+  _LIBCXXABI_HIDDEN virtual ~__pointer_to_member_type_info();
+  _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,
+                                           void *&) const;
+  _LIBCXXABI_HIDDEN bool can_catch_nested(const __shim_type_info *) const;
+};
+
+}  // __cxxabiv1
+
+#endif  // __PRIVATE_TYPEINFO_H_
diff --git a/lib/libcxxabi/src/stdlib_exception.cpp b/lib/libcxxabi/src/stdlib_exception.cpp
new file mode 100644
index 0000000000..88d911d96c
--- /dev/null
+++ b/lib/libcxxabi/src/stdlib_exception.cpp
@@ -0,0 +1,71 @@
+//===---------------------------- exception.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#define _LIBCPP_BUILDING_LIBRARY
+#include <new>
+#include <exception>
+
+namespace std
+{
+
+// exception
+
+exception::~exception() _NOEXCEPT
+{
+}
+
+const char* exception::what() const _NOEXCEPT
+{
+  return "std::exception";
+}
+
+// bad_exception
+
+bad_exception::~bad_exception() _NOEXCEPT
+{
+}
+
+const char* bad_exception::what() const _NOEXCEPT
+{
+  return "std::bad_exception";
+}
+
+
+//  bad_alloc
+
+bad_alloc::bad_alloc() _NOEXCEPT
+{
+}
+
+bad_alloc::~bad_alloc() _NOEXCEPT
+{
+}
+
+const char*
+bad_alloc::what() const _NOEXCEPT
+{
+    return "std::bad_alloc";
+}
+
+// bad_array_new_length
+
+bad_array_new_length::bad_array_new_length() _NOEXCEPT
+{
+}
+
+bad_array_new_length::~bad_array_new_length() _NOEXCEPT
+{
+}
+
+const char*
+bad_array_new_length::what() const _NOEXCEPT
+{
+    return "bad_array_new_length";
+}
+
+}  // std
diff --git a/lib/libcxxabi/src/stdlib_stdexcept.cpp b/lib/libcxxabi/src/stdlib_stdexcept.cpp
new file mode 100644
index 0000000000..2cff8ee2f0
--- /dev/null
+++ b/lib/libcxxabi/src/stdlib_stdexcept.cpp
@@ -0,0 +1,47 @@
+//===------------------------ stdexcept.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/refstring.h"
+#include "stdexcept"
+#include "new"
+#include <cstdlib>
+#include <cstring>
+#include <cstdint>
+#include <cstddef>
+
+static_assert(sizeof(std::__libcpp_refstring) == sizeof(const char *), "");
+
+namespace std  // purposefully not using versioning namespace
+{
+
+logic_error::~logic_error() _NOEXCEPT {}
+
+const char*
+logic_error::what() const _NOEXCEPT
+{
+    return __imp_.c_str();
+}
+
+runtime_error::~runtime_error() _NOEXCEPT {}
+
+const char*
+runtime_error::what() const _NOEXCEPT
+{
+    return __imp_.c_str();
+}
+
+domain_error::~domain_error() _NOEXCEPT {}
+invalid_argument::~invalid_argument() _NOEXCEPT {}
+length_error::~length_error() _NOEXCEPT {}
+out_of_range::~out_of_range() _NOEXCEPT {}
+
+range_error::~range_error() _NOEXCEPT {}
+overflow_error::~overflow_error() _NOEXCEPT {}
+underflow_error::~underflow_error() _NOEXCEPT {}
+
+}  // std
diff --git a/lib/libcxxabi/src/stdlib_typeinfo.cpp b/lib/libcxxabi/src/stdlib_typeinfo.cpp
new file mode 100644
index 0000000000..dbb9623692
--- /dev/null
+++ b/lib/libcxxabi/src/stdlib_typeinfo.cpp
@@ -0,0 +1,52 @@
+//===----------------------------- typeinfo.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <typeinfo>
+
+namespace std
+{
+
+// type_info
+
+type_info::~type_info()
+{
+}
+
+// bad_cast
+
+bad_cast::bad_cast() _NOEXCEPT
+{
+}
+
+bad_cast::~bad_cast() _NOEXCEPT
+{
+}
+
+const char*
+bad_cast::what() const _NOEXCEPT
+{
+  return "std::bad_cast";
+}
+
+// bad_typeid
+
+bad_typeid::bad_typeid() _NOEXCEPT
+{
+}
+
+bad_typeid::~bad_typeid() _NOEXCEPT
+{
+}
+
+const char*
+bad_typeid::what() const _NOEXCEPT
+{
+  return "std::bad_typeid";
+}
+
+}  // std
diff --git a/src-self-hosted/clang_options_data.zig b/src-self-hosted/clang_options_data.zig
index 89cf29024f..2179b47253 100644
--- a/src-self-hosted/clang_options_data.zig
+++ b/src-self-hosted/clang_options_data.zig
@@ -3752,7 +3752,14 @@ flagpd1("nostdinc++"),
     .psl = false,
 },
 flagpd1("nostdlibinc"),
-flagpd1("nostdlib++"),
+.{
+    .name = "nostdlib++",
+    .syntax = .flag,
+    .zig_equivalent = .nostdlib_cpp,
+    .pd1 = true,
+    .pd2 = false,
+    .psl = false,
+},
 flagpd1("nostdsysteminc"),
 flagpd1("objcmt-atomic-property"),
 flagpd1("objcmt-migrate-all"),
diff --git a/src-self-hosted/stage2.zig b/src-self-hosted/stage2.zig
index cd0956cae3..0613634c6a 100644
--- a/src-self-hosted/stage2.zig
+++ b/src-self-hosted/stage2.zig
@@ -114,6 +114,7 @@ const Error = extern enum {
     InvalidAbiVersion,
     InvalidOperatingSystemVersion,
     UnknownClangOption,
+    NestedResponseFile,
 };
 
 const FILE = std.c.FILE;
@@ -1259,6 +1260,7 @@ pub const ClangArgIterator = extern struct {
     argv_ptr: [*]const [*:0]const u8,
     argv_len: usize,
     next_index: usize,
+    root_args: ?*Args,
 
     // ABI warning
     pub const ZigEquivalent = extern enum {
@@ -1273,6 +1275,7 @@ pub const ClangArgIterator = extern struct {
         pic,
         no_pic,
         nostdlib,
+        nostdlib_cpp,
         shared,
         rdynamic,
         wl,
@@ -1282,9 +1285,19 @@ pub const ClangArgIterator = extern struct {
         sanitize,
         linker_script,
         verbose_cmds,
+        exceptions,
+        no_exceptions,
+        rtti,
+        no_rtti,
     };
 
-    fn init(argv: []const [*:0]const u8) ClangArgIterator {
+    const Args = struct {
+        next_index: usize,
+        argv_ptr: [*]const [*:0]const u8,
+        argv_len: usize,
+    };
+
+    pub fn init(argv: []const [*:0]const u8) ClangArgIterator {
         return .{
             .next_index = 2, // `zig cc foo` this points to `foo`
             .has_next = argv.len > 2,
@@ -1295,22 +1308,74 @@ pub const ClangArgIterator = extern struct {
             .other_args_len = undefined,
             .argv_ptr = argv.ptr,
             .argv_len = argv.len,
+            .root_args = null,
         };
     }
 
-    fn next(self: *ClangArgIterator) !void {
+    pub fn next(self: *ClangArgIterator) !void {
         assert(self.has_next);
         assert(self.next_index < self.argv_len);
         // In this state we know that the parameter we are looking at is a root parameter
         // rather than an argument to a parameter.
         self.other_args_ptr = self.argv_ptr + self.next_index;
         self.other_args_len = 1; // We adjust this value below when necessary.
-        const arg = mem.span(self.argv_ptr[self.next_index]);
-        self.next_index += 1;
-        defer {
-            if (self.next_index >= self.argv_len) self.has_next = false;
-        }
+        var arg = mem.span(self.argv_ptr[self.next_index]);
+        self.incrementArgIndex();
+
+        if (mem.startsWith(u8, arg, "@")) {
+            if (self.root_args != null) return error.NestedResponseFile;
+
+            // This is a "compiler response file". We must parse the file and treat its
+            // contents as command line parameters.
+            const allocator = std.heap.c_allocator;
+            const max_bytes = 10 * 1024 * 1024; // 10 MiB of command line arguments is a reasonable limit
+            const resp_file_path = arg[1..];
+            const resp_contents = fs.cwd().readFileAlloc(allocator, resp_file_path, max_bytes) catch |err| {
+                std.debug.warn("unable to read response file '{}': {}\n", .{ resp_file_path, @errorName(err) });
+                process.exit(1);
+            };
+            defer allocator.free(resp_contents);
+            // TODO is there a specification for this file format? Let's find it and make this parsing more robust
+            // at the very least I'm guessing this needs to handle quotes and `#` comments.
+            var it = mem.tokenize(resp_contents, " \t\r\n");
+            var resp_arg_list = std.ArrayList([*:0]const u8).init(allocator);
+            defer resp_arg_list.deinit();
+            {
+                errdefer {
+                    for (resp_arg_list.span()) |item| {
+                        allocator.free(mem.span(item));
+                    }
+                }
+                while (it.next()) |token| {
+                    const dupe_token = try mem.dupeZ(allocator, u8, token);
+                    errdefer allocator.free(dupe_token);
+                    try resp_arg_list.append(dupe_token);
+                }
+                const args = try allocator.create(Args);
+                errdefer allocator.destroy(args);
+                args.* = .{
+                    .next_index = self.next_index,
+                    .argv_ptr = self.argv_ptr,
+                    .argv_len = self.argv_len,
+                };
+                self.root_args = args;
+            }
+            const resp_arg_slice = resp_arg_list.toOwnedSlice();
+            self.next_index = 0;
+            self.argv_ptr = resp_arg_slice.ptr;
+            self.argv_len = resp_arg_slice.len;
+
+            if (resp_arg_slice.len == 0) {
+                self.resolveRespFileArgs();
+                return;
+            }
 
+            self.has_next = true;
+            self.other_args_ptr = self.argv_ptr + self.next_index;
+            self.other_args_len = 1; // We adjust this value below when necessary.
+            arg = mem.span(self.argv_ptr[self.next_index]);
+            self.incrementArgIndex();
+        }
         if (!mem.startsWith(u8, arg, "-")) {
             self.zig_equivalent = .positional;
             self.only_arg = arg.ptr;
@@ -1347,7 +1412,7 @@ pub const ClangArgIterator = extern struct {
                         process.exit(1);
                     }
                     self.only_arg = self.argv_ptr[self.next_index];
-                    self.next_index += 1;
+                    self.incrementArgIndex();
                     self.other_args_len += 1;
                     self.zig_equivalent = clang_arg.zig_equivalent;
 
@@ -1369,7 +1434,7 @@ pub const ClangArgIterator = extern struct {
                         process.exit(1);
                     }
                     self.second_arg = self.argv_ptr[self.next_index];
-                    self.next_index += 1;
+                    self.incrementArgIndex();
                     self.other_args_len += 1;
                     self.zig_equivalent = clang_arg.zig_equivalent;
                     break :find_clang_arg;
@@ -1381,7 +1446,7 @@ pub const ClangArgIterator = extern struct {
                     process.exit(1);
                 }
                 self.only_arg = self.argv_ptr[self.next_index];
-                self.next_index += 1;
+                self.incrementArgIndex();
                 self.other_args_len += 1;
                 self.zig_equivalent = clang_arg.zig_equivalent;
                 break :find_clang_arg;
@@ -1401,6 +1466,28 @@ pub const ClangArgIterator = extern struct {
             process.exit(1);
         }
     }
+
+    fn incrementArgIndex(self: *ClangArgIterator) void {
+        self.next_index += 1;
+        self.resolveRespFileArgs();
+    }
+
+    fn resolveRespFileArgs(self: *ClangArgIterator) void {
+        const allocator = std.heap.c_allocator;
+        if (self.next_index >= self.argv_len) {
+            if (self.root_args) |root_args| {
+                self.next_index = root_args.next_index;
+                self.argv_ptr = root_args.argv_ptr;
+                self.argv_len = root_args.argv_len;
+
+                allocator.destroy(root_args);
+                self.root_args = null;
+            }
+            if (self.next_index >= self.argv_len) {
+                self.has_next = false;
+            }
+        }
+    }
 };
 
 export fn stage2_clang_arg_iterator(
@@ -1413,7 +1500,8 @@ export fn stage2_clang_arg_iterator(
 
 export fn stage2_clang_arg_next(it: *ClangArgIterator) Error {
     it.next() catch |err| switch (err) {
-        error.UnknownClangOption => return .UnknownClangOption,
+        error.NestedResponseFile => return .NestedResponseFile,
+        error.OutOfMemory => return .OutOfMemory,
     };
     return .None;
 }
diff --git a/src/all_types.hpp b/src/all_types.hpp
index b2abd17f99..6c7b465025 100644
--- a/src/all_types.hpp
+++ b/src/all_types.hpp
@@ -2019,6 +2019,7 @@ struct CodeGen {
     ZigLLVMDICompileUnit *compile_unit;
     ZigLLVMDIFile *compile_unit_file;
     LinkLib *libc_link_lib;
+    LinkLib *libcpp_link_lib;
     LLVMTargetDataRef target_data_ref;
     LLVMTargetMachineRef target_machine;
     ZigLLVMDIFile *dummy_di_file;
@@ -2261,6 +2262,8 @@ struct CodeGen {
     bool emit_asm;
     bool emit_llvm_ir;
     bool test_is_evented;
+    bool cpp_rtti;
+    bool cpp_exceptions;
     CodeModel code_model;
 
     Buf *root_out_name;
diff --git a/src/analyze.cpp b/src/analyze.cpp
index 77d3f33331..df7bcdf9de 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -7756,10 +7756,14 @@ LinkLib *create_link_lib(Buf *name) {
 
 LinkLib *add_link_lib(CodeGen *g, Buf *name) {
     bool is_libc = buf_eql_str(name, "c");
+    bool is_libcpp = buf_eql_str(name, "c++") || buf_eql_str(name, "c++abi");
 
     if (is_libc && g->libc_link_lib != nullptr)
         return g->libc_link_lib;
 
+    if (is_libcpp && g->libcpp_link_lib != nullptr)
+        return g->libcpp_link_lib;
+
     for (size_t i = 0; i < g->link_libs_list.length; i += 1) {
         LinkLib *existing_lib = g->link_libs_list.at(i);
         if (buf_eql_buf(existing_lib->name, name)) {
@@ -7772,6 +7776,8 @@ LinkLib *add_link_lib(CodeGen *g, Buf *name) {
 
     if (is_libc)
         g->libc_link_lib = link_lib;
+    if (is_libcpp)
+        g->libcpp_link_lib = link_lib;
 
     return link_lib;
 }
diff --git a/src/analyze.hpp b/src/analyze.hpp
index a7828663b0..ee069427bd 100644
--- a/src/analyze.hpp
+++ b/src/analyze.hpp
@@ -260,6 +260,7 @@ ZigLLVMDIType *get_llvm_di_type(CodeGen *g, ZigType *type);
 enum CSourceKind {
     CSourceKindAsm,
     CSourceKindC,
+    CSourceKindCpp,
 };
 
 void add_cc_args(CodeGen *g, ZigList<const char *> &args, const char *out_dep_path, bool translate_c,
diff --git a/src/codegen.cpp b/src/codegen.cpp
index cb1ab6b6b8..f02253fb1a 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -8448,6 +8448,8 @@ static bool detect_dynamic_link(CodeGen *g) {
         LinkLib *link_lib = g->link_libs_list.at(i);
         if (target_is_libc_lib_name(g->zig_target, buf_ptr(link_lib->name)))
             continue;
+        if (target_is_libcpp_lib_name(g->zig_target, buf_ptr(link_lib->name)))
+            continue;
         return true;
     }
     return false;
@@ -8700,6 +8702,7 @@ Buf *codegen_generate_builtin_source(CodeGen *g) {
     buf_appendf(contents, "pub const object_format = ObjectFormat.%s;\n", cur_obj_fmt);
     buf_appendf(contents, "pub const mode = %s;\n", build_mode_to_str(g->build_mode));
     buf_appendf(contents, "pub const link_libc = %s;\n", bool_to_str(g->libc_link_lib != nullptr));
+    buf_appendf(contents, "pub const link_libcpp = %s;\n", bool_to_str(g->libcpp_link_lib != nullptr));
     buf_appendf(contents, "pub const have_error_return_tracing = %s;\n", bool_to_str(g->have_err_ret_tracing));
     buf_appendf(contents, "pub const valgrind_support = %s;\n", bool_to_str(want_valgrind_support(g)));
     buf_appendf(contents, "pub const position_independent_code = %s;\n", bool_to_str(g->have_pic));
@@ -8781,6 +8784,8 @@ static Error define_builtin_compile_vars(CodeGen *g) {
     cache_bool(&cache_hash, g->is_test_build);
     cache_bool(&cache_hash, g->is_single_threaded);
     cache_bool(&cache_hash, g->test_is_evented);
+    cache_bool(&cache_hash, g->cpp_rtti);
+    cache_bool(&cache_hash, g->cpp_exceptions);
     cache_int(&cache_hash, g->code_model);
     cache_int(&cache_hash, g->zig_target->is_native_os);
     cache_int(&cache_hash, g->zig_target->is_native_cpu);
@@ -8798,6 +8803,7 @@ static Error define_builtin_compile_vars(CodeGen *g) {
     }
     cache_bool(&cache_hash, g->have_err_ret_tracing);
     cache_bool(&cache_hash, g->libc_link_lib != nullptr);
+    cache_bool(&cache_hash, g->libcpp_link_lib != nullptr);
     cache_bool(&cache_hash, g->valgrind_support);
     cache_bool(&cache_hash, g->link_eh_frame_hdr);
     cache_int(&cache_hash, detect_subsystem(g));
@@ -9179,7 +9185,7 @@ void add_cc_args(CodeGen *g, ZigList<const char *> &args, const char *out_dep_pa
     }
 
     if (translate_c) {
-        if (source_kind == CSourceKindC) {
+        if (source_kind != CSourceKindAsm) {
             // this gives us access to preprocessing entities, presumably at
             // the cost of performance
             args.append("-Xclang");
@@ -9205,6 +9211,20 @@ void add_cc_args(CodeGen *g, ZigList<const char *> &args, const char *out_dep_pa
         args.append(g->framework_dirs.at(i));
     }
 
+    if (g->libcpp_link_lib != nullptr) {
+        const char *libcxx_include_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxx" OS_SEP "include",
+                buf_ptr(g->zig_lib_dir)));
+
+        args.append("-isystem");
+        args.append(libcxx_include_path);
+
+        if (target_abi_is_musl(g->zig_target->abi)) {
+            args.append("-D_LIBCPP_HAS_MUSL_LIBC");
+        }
+        args.append("-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS");
+        args.append("-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS");
+    }
+
     // According to Rich Felker libc headers are supposed to go before C language headers.
     // However as noted by @dimenus, appending libc headers before c_headers breaks intrinsics
     // and other compiler specific items.
@@ -9222,6 +9242,7 @@ void add_cc_args(CodeGen *g, ZigList<const char *> &args, const char *out_dep_pa
 
     switch (source_kind) {
         case CSourceKindC:
+        case CSourceKindCpp:
             if (g->zig_target->llvm_cpu_name != nullptr) {
                 args.append("-Xclang");
                 args.append("-target-cpu");
@@ -9238,6 +9259,14 @@ void add_cc_args(CodeGen *g, ZigList<const char *> &args, const char *out_dep_pa
         case CSourceKindAsm:
             break;
     }
+    if (source_kind == CSourceKindCpp) {
+        if (!g->cpp_rtti) {
+            args.append("-fno-rtti");
+        }
+        if (!g->cpp_exceptions) {
+            args.append("-fno-exceptions");
+        }
+    }
     for (size_t i = 0; i < g->zig_target->llvm_cpu_features_asm_len; i += 1) {
         args.append(g->zig_target->llvm_cpu_features_asm_ptr[i]);
     }
@@ -9685,6 +9714,8 @@ Error create_c_object_cache(CodeGen *g, CacheHash **out_cache_hash, bool verbose
     cache_bool(cache_hash, g->have_sanitize_c);
     cache_bool(cache_hash, want_valgrind_support(g));
     cache_bool(cache_hash, g->function_sections);
+    cache_bool(cache_hash, g->cpp_rtti);
+    cache_bool(cache_hash, g->cpp_exceptions);
     cache_int(cache_hash, g->code_model);
 
     for (size_t arg_i = 0; arg_i < g->clang_argv_len; arg_i += 1) {
@@ -10519,6 +10550,8 @@ static Error check_cache(CodeGen *g, Buf *manifest_dir, Buf *digest) {
     cache_bool(ch, g->emit_bin);
     cache_bool(ch, g->emit_llvm_ir);
     cache_bool(ch, g->emit_asm);
+    cache_bool(ch, g->cpp_rtti);
+    cache_bool(ch, g->cpp_exceptions);
     cache_usize(ch, g->version_major);
     cache_usize(ch, g->version_minor);
     cache_usize(ch, g->version_patch);
@@ -10823,6 +10856,8 @@ CodeGen *create_child_codegen(CodeGen *parent_gen, Buf *root_src_path, OutType o
         parent_gen->build_mode, parent_gen->zig_lib_dir, libc, get_global_cache_dir(), false, child_progress_node);
     child_gen->root_out_name = buf_create_from_str(name);
     child_gen->disable_gen_h = true;
+    child_gen->cpp_rtti = parent_gen->cpp_rtti;
+    child_gen->cpp_exceptions = parent_gen->cpp_exceptions;
     child_gen->want_stack_check = WantStackCheckDisabled;
     child_gen->want_sanitize_c = WantCSanitizeDisabled;
     child_gen->verbose_tokenize = parent_gen->verbose_tokenize;
diff --git a/src/error.cpp b/src/error.cpp
index c246ea5f31..76b510ecf3 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -84,6 +84,7 @@ const char *err_str(Error err) {
         case ErrorInvalidAbiVersion: return "invalid C ABI version";
         case ErrorInvalidOperatingSystemVersion: return "invalid operating system version";
         case ErrorUnknownClangOption: return "unknown Clang option";
+        case ErrorNestedResponseFile: return "nested response file";
     }
     return "(invalid error)";
 }
diff --git a/src/install_files.h b/src/install_files.h
index 8c81a3fc80..8e7431145e 100644
--- a/src/install_files.h
+++ b/src/install_files.h
@@ -1841,4 +1841,67 @@ static const char *ZIG_MUSL_COMPAT_TIME32_FILES[] = {
 "musl/compat/time32/wait3_time32.c",
 "musl/compat/time32/wait4_time32.c",
 };
+static const char *ZIG_LIBCXXABI_FILES[] = {
+"src/abort_message.cpp",
+"src/cxa_aux_runtime.cpp",
+"src/cxa_default_handlers.cpp",
+"src/cxa_demangle.cpp",
+"src/cxa_exception.cpp",
+"src/cxa_exception_storage.cpp",
+"src/cxa_guard.cpp",
+"src/cxa_handlers.cpp",
+"src/cxa_noexception.cpp",
+"src/cxa_personality.cpp",
+"src/cxa_thread_atexit.cpp",
+"src/cxa_unexpected.cpp",
+"src/cxa_vector.cpp",
+"src/cxa_virtual.cpp",
+"src/fallback_malloc.cpp",
+"src/private_typeinfo.cpp",
+"src/stdlib_exception.cpp",
+"src/stdlib_stdexcept.cpp",
+"src/stdlib_typeinfo.cpp",
+};
+static const char *ZIG_LIBCXX_FILES[] = {
+"src/algorithm.cpp",
+"src/any.cpp",
+"src/bind.cpp",
+"src/charconv.cpp",
+"src/chrono.cpp",
+"src/condition_variable.cpp",
+"src/condition_variable_destructor.cpp",
+"src/debug.cpp",
+"src/exception.cpp",
+"src/experimental/memory_resource.cpp",
+"src/filesystem/directory_iterator.cpp",
+"src/filesystem/operations.cpp",
+"src/functional.cpp",
+"src/future.cpp",
+"src/hash.cpp",
+"src/ios.cpp",
+"src/iostream.cpp",
+"src/locale.cpp",
+"src/memory.cpp",
+"src/mutex.cpp",
+"src/mutex_destructor.cpp",
+"src/new.cpp",
+"src/optional.cpp",
+"src/random.cpp",
+"src/regex.cpp",
+"src/shared_mutex.cpp",
+"src/stdexcept.cpp",
+"src/string.cpp",
+"src/strstream.cpp",
+"src/support/solaris/xlocale.cpp",
+"src/support/win32/locale_win32.cpp",
+"src/support/win32/support.cpp",
+"src/support/win32/thread_win32.cpp",
+"src/system_error.cpp",
+"src/thread.cpp",
+"src/typeinfo.cpp",
+"src/utility.cpp",
+"src/valarray.cpp",
+"src/variant.cpp",
+"src/vector.cpp",
+};
 #endif
diff --git a/src/link.cpp b/src/link.cpp
index 25b913be21..d9b784129d 100644
--- a/src/link.cpp
+++ b/src/link.cpp
@@ -14,6 +14,8 @@
 #include "glibc.hpp"
 
 static const char *msvcrt_common_src[] = {
+    "misc" OS_SEP "_create_locale.c",
+    "misc" OS_SEP "_free_locale.c",
     "misc" OS_SEP "onexit_table.c",
     "misc" OS_SEP "register_tls_atexit.c",
     "stdio" OS_SEP "acrt_iob_func.c",
@@ -632,12 +634,17 @@ static const char *build_libunwind(CodeGen *parent, Stage2ProgressNode *progress
         }
         c_file->args.append("-I");
         c_file->args.append(path_from_libunwind(parent, "include"));
-        c_file->args.append("-fPIC");
+        if (target_supports_fpic(parent->zig_target)) {
+            c_file->args.append("-fPIC");
+        }
         c_file->args.append("-D_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS");
         c_file->args.append("-Wa,--noexecstack");
-        if (parent->zig_target->is_native_os && parent->zig_target->is_native_cpu) {
-            c_file->args.append("-D_LIBUNWIND_IS_NATIVE_ONLY");
-        }
+
+        // This is intentionally always defined because the macro definition means, should it only
+        // build for the target specified by compiler defines. Since we pass -target the compiler
+        // defines will be correct.
+        c_file->args.append("-D_LIBUNWIND_IS_NATIVE_ONLY");
+
         if (parent->build_mode == BuildModeDebug) {
             c_file->args.append("-D_DEBUG");
         }
@@ -1107,6 +1114,128 @@ static const char *build_musl(CodeGen *parent, Stage2ProgressNode *progress_node
     return buf_ptr(&child_gen->bin_file_output_path);
 }
 
+static const char *build_libcxxabi(CodeGen *parent, Stage2ProgressNode *progress_node) {
+    CodeGen *child_gen = create_child_codegen(parent, nullptr, OutTypeLib, nullptr, "c++abi", progress_node);
+    codegen_add_link_lib(child_gen, buf_create_from_str("c"));
+
+    ZigList<CFile *> c_source_files = {0};
+
+    const char *cxxabi_include_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxxabi" OS_SEP "include",
+                buf_ptr(parent->zig_lib_dir)));
+    const char *cxx_include_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxx" OS_SEP "include",
+                buf_ptr(parent->zig_lib_dir)));
+
+    for (size_t i = 0; i < array_length(ZIG_LIBCXXABI_FILES); i += 1) {
+        const char *rel_src_path = ZIG_LIBCXXABI_FILES[i];
+
+        CFile *c_file = heap::c_allocator.create<CFile>();
+        c_file->source_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxxabi" OS_SEP "%s",
+                    buf_ptr(parent->zig_lib_dir), rel_src_path));
+
+        c_file->args.append("-DHAVE___CXA_THREAD_ATEXIT_IMPL");
+        c_file->args.append("-D_LIBCPP_DISABLE_EXTERN_TEMPLATE");
+        c_file->args.append("-D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS");
+        c_file->args.append("-D_LIBCXXABI_BUILDING_LIBRARY");
+        c_file->args.append("-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS");
+        c_file->args.append("-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS");
+
+        if (target_abi_is_musl(parent->zig_target->abi)) {
+            c_file->args.append("-D_LIBCPP_HAS_MUSL_LIBC");
+        }
+
+        c_file->args.append("-I");
+        c_file->args.append(cxxabi_include_path);
+
+        c_file->args.append("-I");
+        c_file->args.append(cxx_include_path);
+
+        c_file->args.append("-O3");
+        c_file->args.append("-DNDEBUG");
+        if (target_supports_fpic(parent->zig_target)) {
+            c_file->args.append("-fPIC");
+        }
+        c_file->args.append("-nostdinc++");
+        c_file->args.append("-fstrict-aliasing");
+        c_file->args.append("-funwind-tables");
+        c_file->args.append("-D_DEBUG");
+        c_file->args.append("-UNDEBUG");
+        c_file->args.append("-std=c++11");
+
+        c_source_files.append(c_file);
+    }
+
+
+    child_gen->c_source_files = c_source_files;
+    codegen_build_and_link(child_gen);
+    return buf_ptr(&child_gen->bin_file_output_path);
+}
+
+static const char *build_libcxx(CodeGen *parent, Stage2ProgressNode *progress_node) {
+    CodeGen *child_gen = create_child_codegen(parent, nullptr, OutTypeLib, nullptr, "c++", progress_node);
+    codegen_add_link_lib(child_gen, buf_create_from_str("c"));
+
+    ZigList<CFile *> c_source_files = {0};
+
+    const char *cxxabi_include_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxxabi" OS_SEP "include",
+                buf_ptr(parent->zig_lib_dir)));
+    const char *cxx_include_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxx" OS_SEP "include",
+                buf_ptr(parent->zig_lib_dir)));
+
+    for (size_t i = 0; i < array_length(ZIG_LIBCXX_FILES); i += 1) {
+        const char *rel_src_path = ZIG_LIBCXX_FILES[i];
+
+        Buf *src_path_buf = buf_create_from_str(rel_src_path);
+        if (parent->zig_target->os == OsWindows) {
+            // filesystem stuff isn't supported on Windows
+            if (buf_starts_with_str(src_path_buf, "src/filesystem/")) {
+                continue;
+            }
+        } else {
+            if (buf_starts_with_str(src_path_buf, "src/support/win32/")) {
+                continue;
+            }
+        }
+
+        CFile *c_file = heap::c_allocator.create<CFile>();
+        c_file->source_path = buf_ptr(buf_sprintf("%s" OS_SEP "libcxx" OS_SEP "%s",
+                    buf_ptr(parent->zig_lib_dir), rel_src_path));
+
+        c_file->args.append("-DNDEBUG");
+        c_file->args.append("-D_LIBCPP_BUILDING_LIBRARY");
+        c_file->args.append("-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER");
+        c_file->args.append("-DLIBCXX_BUILDING_LIBCXXABI");
+        c_file->args.append("-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS");
+        c_file->args.append("-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS");
+
+        if (target_abi_is_musl(parent->zig_target->abi)) {
+            c_file->args.append("-D_LIBCPP_HAS_MUSL_LIBC");
+        }
+
+        c_file->args.append("-I");
+        c_file->args.append(cxx_include_path);
+
+        c_file->args.append("-I");
+        c_file->args.append(cxxabi_include_path);
+
+        c_file->args.append("-O3");
+        c_file->args.append("-DNDEBUG");
+        if (target_supports_fpic(parent->zig_target)) {
+            c_file->args.append("-fPIC");
+        }
+        c_file->args.append("-nostdinc++");
+        c_file->args.append("-fvisibility-inlines-hidden");
+        c_file->args.append("-std=c++14");
+        c_file->args.append("-Wno-user-defined-literals");
+
+        c_source_files.append(c_file);
+    }
+
+
+    child_gen->c_source_files = c_source_files;
+    codegen_build_and_link(child_gen);
+    return buf_ptr(&child_gen->bin_file_output_path);
+}
+
 static void add_msvcrt_os_dep(CodeGen *parent, CodeGen *child_gen, const char *src_path) {
     CFile *c_file = heap::c_allocator.create<CFile>();
     c_file->source_path = buf_ptr(buf_sprintf("%s" OS_SEP "libc" OS_SEP "mingw" OS_SEP "%s",
@@ -1770,6 +1899,10 @@ static void construct_linker_job_elf(LinkJob *lj) {
             // libc is linked specially
             continue;
         }
+        if (buf_eql_str(link_lib->name, "c++") || buf_eql_str(link_lib->name, "c++abi")) {
+            // libc++ is linked specially
+            continue;
+        }
         if (g->libc == nullptr && target_is_libc_lib_name(g->zig_target, buf_ptr(link_lib->name))) {
             // these libraries are always linked below when targeting glibc
             continue;
@@ -1785,6 +1918,11 @@ static void construct_linker_job_elf(LinkJob *lj) {
         lj->args.append(buf_ptr(arg));
     }
 
+    // libc++ dep
+    if (g->libcpp_link_lib != nullptr && g->out_type != OutTypeObj) {
+        lj->args.append(build_libcxxabi(g, lj->build_dep_prog_node));
+        lj->args.append(build_libcxx(g, lj->build_dep_prog_node));
+    }
 
     // libc dep
     if (g->libc_link_lib != nullptr && g->out_type != OutTypeObj) {
@@ -1815,6 +1953,8 @@ static void construct_linker_job_elf(LinkJob *lj) {
                 lj->args.append(build_libunwind(g, lj->build_dep_prog_node));
             }
             lj->args.append(build_musl(g, lj->build_dep_prog_node));
+        } else if (g->libcpp_link_lib != nullptr) {
+            lj->args.append(build_libunwind(g, lj->build_dep_prog_node));
         } else {
             zig_unreachable();
         }
@@ -2303,6 +2443,13 @@ static void construct_linker_job_coff(LinkJob *lj) {
             break;
     }
 
+    // libc++ dep
+    if (g->libcpp_link_lib != nullptr && g->out_type != OutTypeObj) {
+        lj->args.append(build_libcxxabi(g, lj->build_dep_prog_node));
+        lj->args.append(build_libcxx(g, lj->build_dep_prog_node));
+        lj->args.append(build_libunwind(g, lj->build_dep_prog_node));
+    }
+
     if (g->out_type == OutTypeExe || (g->out_type == OutTypeLib && g->is_dynamic)) {
         if (g->libc_link_lib == nullptr && !g->is_dummy_so) {
             Buf *libc_a_path = build_c(g, OutTypeLib, lj->build_dep_prog_node);
@@ -2319,6 +2466,9 @@ static void construct_linker_job_coff(LinkJob *lj) {
         if (buf_eql_str(link_lib->name, "c")) {
             continue;
         }
+        if (buf_eql_str(link_lib->name, "c++") || buf_eql_str(link_lib->name, "c++abi")) {
+            continue;
+        }
         bool is_sys_lib = is_mingw_link_lib(link_lib->name);
         if (have_windows_dll_import_libs && is_sys_lib) {
             continue;
@@ -2454,6 +2604,12 @@ static void construct_linker_job_macho(LinkJob *lj) {
         lj->args.append((const char *)buf_ptr(g->link_objects.at(i)));
     }
 
+    // libc++ dep
+    if (g->libcpp_link_lib != nullptr && g->out_type != OutTypeObj) {
+        lj->args.append(build_libcxxabi(g, lj->build_dep_prog_node));
+        lj->args.append(build_libcxx(g, lj->build_dep_prog_node));
+    }
+
     // compiler_rt on darwin is missing some stuff, so we still build it and rely on LinkOnce
     if (g->out_type == OutTypeExe || is_dyn_lib) {
         Buf *compiler_rt_o_path = build_compiler_rt(g, OutTypeLib, lj->build_dep_prog_node);
diff --git a/src/main.cpp b/src/main.cpp
index a543b43579..d2936c3b52 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -412,6 +412,7 @@ static int main0(int argc, char **argv) {
     ZigList<const char *> framework_dirs = {0};
     ZigList<const char *> frameworks = {0};
     bool have_libc = false;
+    bool have_libcpp = false;
     const char *target_string = nullptr;
     bool rdynamic = false;
     const char *linker_script = nullptr;
@@ -456,6 +457,9 @@ static int main0(int argc, char **argv) {
     const char *override_soname = nullptr;
     bool only_preprocess = false;
     bool ensure_libc_on_non_freestanding = false;
+    bool ensure_libcpp_on_non_freestanding = false;
+    bool cpp_rtti = true;
+    bool cpp_exceptions = true;
 
     ZigList<const char *> llvm_argv = {0};
     llvm_argv.append("zig (LLVM option parsing)");
@@ -580,10 +584,11 @@ static int main0(int argc, char **argv) {
         return (term.how == TerminationIdClean) ? term.code : -1;
     } else if (argc >= 2 && strcmp(argv[1], "fmt") == 0) {
         return stage2_fmt(argc, argv);
-    } else if (argc >= 2 && strcmp(argv[1], "cc") == 0) {
+    } else if (argc >= 2 && (strcmp(argv[1], "cc") == 0 || strcmp(argv[1], "c++") == 0)) {
         emit_h = false;
         strip = true;
         ensure_libc_on_non_freestanding = true;
+        ensure_libcpp_on_non_freestanding = (strcmp(argv[1], "c++") == 0);
 
         bool c_arg = false;
         Stage2ClangArgIterator it;
@@ -632,6 +637,8 @@ static int main0(int argc, char **argv) {
                 case Stage2ClangArgL: // -l
                     if (strcmp(it.only_arg, "c") == 0)
                         have_libc = true;
+                    if (strcmp(it.only_arg, "c++") == 0)
+                        have_libcpp = true;
                     link_libs.append(it.only_arg);
                     break;
                 case Stage2ClangArgIgnore:
@@ -648,6 +655,9 @@ static int main0(int argc, char **argv) {
                 case Stage2ClangArgNoStdLib:
                     ensure_libc_on_non_freestanding = false;
                     break;
+                case Stage2ClangArgNoStdLibCpp:
+                    ensure_libcpp_on_non_freestanding = false;
+                    break;
                 case Stage2ClangArgShared:
                     is_dynamic = true;
                     is_shared_lib = true;
@@ -712,6 +722,18 @@ static int main0(int argc, char **argv) {
                     verbose_cc = true;
                     verbose_link = true;
                     break;
+                case Stage2ClangArgExceptions:
+                    cpp_exceptions = true;
+                    break;
+                case Stage2ClangArgNoExceptions:
+                    cpp_exceptions = false;
+                    break;
+                case Stage2ClangArgRtti:
+                    cpp_rtti = true;
+                    break;
+                case Stage2ClangArgNoRtti:
+                    cpp_rtti = false;
+                    break;
             }
         }
         // Parse linker args
@@ -916,6 +938,8 @@ static int main0(int argc, char **argv) {
                 const char *l = &arg[2];
                 if (strcmp(l, "c") == 0)
                     have_libc = true;
+                if (strcmp(l, "c++") == 0)
+                    have_libcpp = true;
                 link_libs.append(l);
             } else if (arg[1] == 'I' && arg[2] != 0) {
                 clang_argv.append("-I");
@@ -1057,6 +1081,8 @@ static int main0(int argc, char **argv) {
                 } else if (strcmp(arg, "--library") == 0 || strcmp(arg, "-l") == 0) {
                     if (strcmp(argv[i], "c") == 0)
                         have_libc = true;
+                    if (strcmp(argv[i], "c++") == 0)
+                        have_libcpp = true;
                     link_libs.append(argv[i]);
                 } else if (strcmp(arg, "--forbid-library") == 0) {
                     forbidden_link_libs.append(argv[i]);
@@ -1221,6 +1247,10 @@ static int main0(int argc, char **argv) {
         have_libc = true;
         link_libs.append("c");
     }
+    if (!have_libcpp && ensure_libcpp_on_non_freestanding && target.os != OsFreestanding) {
+        have_libcpp = true;
+        link_libs.append("c++");
+    }
 
     Buf zig_triple_buf = BUF_INIT;
     target_triple_zig(&zig_triple_buf, &target);
@@ -1287,6 +1317,8 @@ static int main0(int argc, char **argv) {
             LinkLib *link_lib = codegen_add_link_lib(g, buf_create_from_str(link_libs.at(i)));
             link_lib->provided_explicitly = true;
         }
+        g->cpp_rtti = cpp_rtti;
+        g->cpp_exceptions = cpp_exceptions;
         g->subsystem = subsystem;
         g->valgrind_support = valgrind_support;
         g->want_pic = want_pic;
@@ -1433,6 +1465,8 @@ static int main0(int argc, char **argv) {
             }
             CodeGen *g = codegen_create(main_pkg_path, zig_root_source_file, &target, out_type, build_mode,
                     override_lib_dir, libc, cache_dir_buf, cmd == CmdTest, root_progress_node);
+            g->cpp_rtti = cpp_rtti;
+            g->cpp_exceptions = cpp_exceptions;
             if (llvm_argv.length >= 2) codegen_set_llvm_argv(g, llvm_argv.items + 1, llvm_argv.length - 2);
             g->valgrind_support = valgrind_support;
             g->link_eh_frame_hdr = link_eh_frame_hdr;
diff --git a/src/stage2.h b/src/stage2.h
index 4b86fdc059..ed7caebcb0 100644
--- a/src/stage2.h
+++ b/src/stage2.h
@@ -106,6 +106,7 @@ enum Error {
     ErrorInvalidAbiVersion,
     ErrorInvalidOperatingSystemVersion,
     ErrorUnknownClangOption,
+    ErrorNestedResponseFile,
 };
 
 // ABI warning
@@ -334,6 +335,7 @@ enum Stage2ClangArg {
     Stage2ClangArgPIC,
     Stage2ClangArgNoPIC,
     Stage2ClangArgNoStdLib,
+    Stage2ClangArgNoStdLibCpp,
     Stage2ClangArgShared,
     Stage2ClangArgRDynamic,
     Stage2ClangArgWL,
@@ -343,6 +345,10 @@ enum Stage2ClangArg {
     Stage2ClangArgSanitize,
     Stage2ClangArgLinkerScript,
     Stage2ClangArgVerboseCmds,
+    Stage2ClangArgExceptions,
+    Stage2ClangArgNoExceptions,
+    Stage2ClangArgRtti,
+    Stage2ClangArgNoRtti,
 };
 
 // ABI warning
@@ -356,6 +362,7 @@ struct Stage2ClangArgIterator {
     const char **argv_ptr;
     size_t argv_len;
     size_t next_index;
+    size_t root_args;
 };
 
 // ABI warning
diff --git a/src/target.cpp b/src/target.cpp
index 63360fc029..59b1addc33 100644
--- a/src/target.cpp
+++ b/src/target.cpp
@@ -1229,6 +1229,13 @@ bool target_is_libc_lib_name(const ZigTarget *target, const char *name) {
     return false;
 }
 
+bool target_is_libcpp_lib_name(const ZigTarget *target, const char *name) {
+    if (strcmp(name, "c++") == 0 || strcmp(name, "c++abi") == 0)
+        return true;
+
+    return false;
+}
+
 size_t target_libc_count(void) {
     return array_length(libcs_available);
 }
diff --git a/src/target.hpp b/src/target.hpp
index 01f2c6b168..c3f8530e02 100644
--- a/src/target.hpp
+++ b/src/target.hpp
@@ -102,6 +102,7 @@ bool target_os_requires_libc(Os os);
 bool target_can_build_libc(const ZigTarget *target);
 const char *target_libc_generic_name(const ZigTarget *target);
 bool target_is_libc_lib_name(const ZigTarget *target, const char *name);
+bool target_is_libcpp_lib_name(const ZigTarget *target, const char *name);
 bool target_supports_fpic(const ZigTarget *target);
 bool target_supports_clang_march_native(const ZigTarget *target);
 bool target_requires_pic(const ZigTarget *target, bool linking_libc);
diff --git a/tools/update_clang_options.zig b/tools/update_clang_options.zig
index 97be4978d2..94dee90142 100644
--- a/tools/update_clang_options.zig
+++ b/tools/update_clang_options.zig
@@ -63,6 +63,10 @@ const known_options = [_]KnownOpt{
         .ident = "nostdlib",
     },
     .{
+        .name = "nostdlib++",
+        .ident = "nostdlib_cpp",
+    },
+    .{
         .name = "shared",
         .ident = "shared",
     },
@@ -154,6 +158,22 @@ const known_options = [_]KnownOpt{
         .name = "###",
         .ident = "verbose_cmds",
     },
+    .{
+        .name = "fexceptions",
+        .ident = "exceptions",
+    },
+    .{
+        .name = "fno-exceptions",
+        .ident = "no_exceptions",
+    },
+    .{
+        .name = "frtti",
+        .ident = "rtti",
+    },
+    .{
+        .name = "fno-rtti",
+        .ident = "no_rtti",
+    },
 };
 
 const blacklisted_options = [_][]const u8{};