diff --git a/llvm/tools/llvm-libgcc/CMakeLists.txt b/llvm/tools/llvm-libgcc/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/CMakeLists.txt
@@ -0,0 +1,51 @@
+cmake_minimum_required(VERSION 3.13.4)
+
+# If we are not building as a part of LLVM, build llvm-libgcc as a standalone
+# project, using compiler-rt and libunwind external libraries.
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  project(LLVM_LIBGCC)
+  if(NOT LLVM_LIBGCC_LIBUNWIND_DIR)
+    message(FATAL_ERROR
+      "We're building llvm-libgcc as a standalone project, but we didn't "
+      " supply a path to LLVM_LIBGCC_LIBUNWIND_DIR. It's not possible to build "
+      "llvm-libgcc without this path!")
+  endif()
+elseif(NOT LLVM_ENABLE_LIBGCC)
+  return()
+endif()
+
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}")
+
+set(LLVM_LIBGCC_SYSROOT "${CMAKE_INSTALL_PREFIX}" CACHE PATH
+    "Assumes this path as the root directory when setting symlinks.")
+
+set(LLVM_LIBGCC_COMPILER_RT_DIR "" CACHE PATH
+    "Absolute path to a pre-existing compiler-rt builtins.")
+find_package(CompilerRT REQUIRED)
+string(REGEX REPLACE "^${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/*" ""
+       LLVM_LIBGCC_COMPILER_RT "${LLVM_LIBGCC_COMPILER_RT}")
+
+set(LLVM_LIBGCC_LIBUNWIND_DIR "" CACHE PATH
+    "Absolute path to a pre-existing libunwind.a.")
+find_package(LLVMLibunwind REQUIRED)
+string(REGEX REPLACE "^${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/*" ""
+       LLVM_LIBGCC_UNWIND_STATIC "${LLVM_LIBGCC_UNWIND_STATIC}")
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
+
+add_custom_target(
+  always_run_target ALL
+  DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver"
+)
+
+set(LLVM_LIBGCC_PYTHON_SCRIPT "version-scripts/generate_version_script.py")
+
+add_custom_command(
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver"
+  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/${LLVM_LIBGCC_PYTHON_SCRIPT}"
+  COMMAND python "${CMAKE_CURRENT_SOURCE_DIR}/${LLVM_LIBGCC_PYTHON_SCRIPT}" "--target=${LLVM_DEFAULT_TARGET_TRIPLE}"
+)
+
+add_subdirectory(lib)
diff --git a/llvm/tools/llvm-libgcc/FindCompilerRT.cmake b/llvm/tools/llvm-libgcc/FindCompilerRT.cmake
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/FindCompilerRT.cmake
@@ -0,0 +1,101 @@
+include(FindPackageHandleStandardArgs)
+include(CheckLibraryExists)
+
+function(building_compiler_rt)
+  if(LLVM_LIBGCC_COMPILER_RT_DIR)
+    return()
+  endif()
+
+  list(FIND LLVM_ENABLE_PROJECTS compiler-rt LLVM_LIBGCC_HAS_COMPILER_RT)
+  if(NOT LLVM_LIBGCC_HAS_COMPILER_RT)
+    return()
+  endif()
+
+  if(NOT COMPILER_RT_BUILD_BUILTINS)
+    message(SEND_ERROR
+      "When building llvm-libgcc alongside compiler-rt, we need to set "
+      "-DCOMPILER_RT_BUILD_BUILTINS=On so we can export all the necessary "
+      "symbols.")
+    return()
+  endif()
+
+  if(NOT COMPILER_RT_BUILTINS_HIDE_SYMBOLS)
+    message(SEND_ERROR
+      "When building llvm-libgcc alongside compiler-rt, we need to set "
+      "-DCOMPILER_RT_BUILTINS_HIDE_SYMBOLS=Off so we can export all the "
+      "necessary symbols.")
+    return()
+  endif()
+
+  set(LLVM_LIBGCC_COMPILER_RT builtins)
+  set(CompilerRT_FOUND ON)
+  message(STATUS "llvm-libgcc is using in-tree compiler-rt")
+endfunction()
+
+function(find_external_compiler_rt)
+  if(NOT ${CMAKE_CHECK_CXX_COMPILER_ID} MATCHES Clang AND
+     NOT LLVM_LIBGCC_COMPILER_RT_DIR)
+    message(STATUS
+      "When building llvm-libgcc without compiler-rt (e.g. as a standalone "
+      "project), we either need to be using Clang, or "
+      "'LLVM_LIBGCC_COMPILER_RT_INSTALL_DIRECTORY' must be set to a directory.")
+    return()
+  endif()
+
+  if(LLVM_LIBGCC_COMPILER_RT_DIR)
+    set(LLVM_LIBGCC_PATH_TO_RTLIB
+      "${LLVM_LIBGCC_COMPILER_RT_DIR}/libclang_rt.builtins.a")
+
+    check_library_exists("${LLVM_LIBGCC_PATH_TO_RTLIB}" emutls_key_destructor
+      LLVM_LIBGCC_HAS_EXTERNAL_RTLIB)
+    if (NOT LLVM_LIBGCC_HAS_EXTERNAL_RTLIB)
+      message(SEND_ERROR
+        "When using LLVM_LIBGCC_COMPILER_RT_DIR='${LLVM_LIBGCC_COMPILER_RT_DIR}', "
+        "we couldn't path '${LLVM_LIBGCC_PATH_TO_RTLIB}'. There could be a few "
+        "reasons for this (e.g. typo in path or wrong permissions for file), "
+        "and a manual inspection is necessary.")
+      return()
+    endif()
+
+    set(LLVM_LIBGCC_COMPILER_RT "${LLVM_LIBGCC_PATH_TO_RTLIB}" PARENT_SCOPE)
+    return()
+  endif()
+
+  execute_process(COMMAND "${CMAKE_CXX_COMPILER}"
+    ${CMAKE_CXX_FLAGS}
+    --rtlib=compiler-rt
+    --print-libgcc-file-name
+    RESULT_VARIABLE HAD_ERROR
+    OUTPUT_VARIABLE LLVM_LIBGCC_COMPILER_RT)
+  string(STRIP "${LLVM_LIBGCC_COMPILER_RT}" LLVM_LIBGCC_COMPILER_RT)
+
+  if(HAD_ERROR)
+    message(STATUS "llvm-libgcc unable to find compiler-rt builtins: got return code ${HAD_ERROR}")
+    unset(LLVM_LIBGCC_COMPILER_RT)
+    return()
+  endif()
+
+  if(NOT EXISTS "${LLVM_LIBGCC_COMPILER_RT}")
+    message(STATUS "llvm-libgcc unable to find path '${LLVM_LIBGCC_COMPILER_RT}'")
+    unset(LLVM_LIBGCC_COMPILER_RT)
+  endif()
+
+  set(LLVM_LIBGCC_COMPILER_RT "${LLVM_LIBGCC_COMPILER_RT}" PARENT_SCOPE)
+endfunction()
+
+set(CompilerRT_FOUND OFF)
+if(NOT CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  building_compiler_rt()
+endif()
+
+if(NOT CompilerRT_FOUND)
+  find_external_compiler_rt()
+  if(LLVM_LIBGCC_COMPILER_RT)
+    string(REGEX REPLACE "^${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/*" ""
+         LLVM_LIBGCC_COMPILER_RT "${LLVM_LIBGCC_COMPILER_RT}")
+    message(STATUS "llvm-libgcc is using a pre-installed compiler-rt: ${LLVM_LIBGCC_COMPILER_RT}")
+    set(CompilerRT_FOUND ON)
+  endif()
+endif()
+
+find_package_handle_standard_args(CompilerRT REQUIRED_VARS CompilerRT_FOUND)
diff --git a/llvm/tools/llvm-libgcc/FindLLVMLibunwind.cmake b/llvm/tools/llvm-libgcc/FindLLVMLibunwind.cmake
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/FindLLVMLibunwind.cmake
@@ -0,0 +1,56 @@
+include(FindPackageHandleStandardArgs)
+
+function(building_libunwind)
+  list(FIND LLVM_ENABLE_PROJECTS libunwind LLVM_LIBGCC_HAS_LIBUNWIND)
+  if(NOT LLVM_LIBGCC_HAS_LIBUNWIND)
+    return()
+  endif()
+
+  if(NOT LIBUNWIND_USE_COMPILER_RT)
+    message(SEND_ERROR
+      "When we're building llvm-libgcc alongside libunwind, we need to set "
+      "'-DLIBUNWIND_USE_COMPILER_RT=On'.")
+  endif()
+
+  if(LIBUNWIND_INSTALL_SHARED_LIBRARY)
+    message(SEND_ERROR
+      "When we're building llvm-libgcc alongside libunwind, llvm-libgcc will "
+      "be the owner of libunwind.so. To prevent the projects from clashing, we "
+      "need to set '-DLIBUNWIND_INSTALL_SHARED_LIBRARY=Off'.")
+  endif()
+
+  if(NOT (LIBUNWIND_SUPPORTS_FNO_EXCEPTIONS_FLAG AND
+          LIBUNWIND_SUPPORTS_FUNWIND_TABLES_FLAG))
+    message(SEND_ERROR
+      "Compiler doesn't support generation of unwind tables if exception "
+      "support is disabled.  Building libunwind DSO with runtime dependency "
+      "on C++ ABI library is not supported.")
+  endif()
+
+  set(LLVM_LIBGCC_UNWIND_STATIC unwind_static PARENT_SCOPE)
+  set(LLVMLibunwind_FOUND ON PARENT_SCOPE)
+  message(STATUS "llvm-libgcc is using in-tree libunwind")
+endfunction()
+
+function(find_external_libunwind)
+  if (NOT EXISTS "${LLVM_LIBGCC_LIBUNWIND_DIR}/libunwind.a")
+    message(SEND_ERROR
+      "When using LLVM_LIBGCC_LIBUNWIND_DIR='${LLVM_LIBGCC_LIBUNWIND_DIR}', we "
+      "couldn't find '${LLVM_LIBGCC_LIBUNWIND_DIR}/libunwind.a'. There could "
+      "be a few reasons for this (e.g. typo in path or wrong permissions for "
+      "file), and a manual inspection is necessary.")
+  endif()
+
+  set(LLVM_LIBGCC_UNWIND_STATIC "${LLVM_LIBGCC_LIBUNWIND_DIR}/libunwind.a" PARENT_SCOPE)
+  set(LLVMLibunwind_FOUND ON PARENT_SCOPE)
+endfunction()
+
+set(LLVMLibunwind_FOUND OFF)
+if(NOT CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  building_libunwind()
+else()
+  find_external_libunwind()
+  message(STATUS "llvm-libgcc is using a pre-built libunwind: ${LLVM_LIBGCC_UNWIND_STATIC}")
+endif()
+
+find_package_handle_standard_args(LLVMLibunwind REQUIRED_VARS LLVMLibunwind_FOUND)
diff --git a/llvm/tools/llvm-libgcc/docs/LLVMLibgcc.rst b/llvm/tools/llvm-libgcc/docs/LLVMLibgcc.rst
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/docs/LLVMLibgcc.rst
@@ -0,0 +1,213 @@
+.. llvm-libgcc:
+
+===========
+llvm-libgcc
+===========
+
+.. contents::
+  :local:
+
+**Note that these instructions assume a Linux and bash-friendly environment.
+YMMV if you’re on a non Linux-based platform.**
+
+.. _introduction:
+
+Motivation
+============
+
+Enabling libunwind as a replacement for libgcc on Linux has proven to be
+challenging since libgcc_s.so is a required dependency in the [Linux standard
+base][5]. Some software is transitively dependent on libgcc because glibc makes
+hardcoded calls to functions in libgcc_s. For example, the function
+``__GI___backtrace`` eventually makes its way to a [hardcoded dlopen to libgcc_s'
+_Unwind_Backtrace][1]. Since libgcc_{eh.a,s.so} and libunwind have the same ABI,
+but different implementations, the two libraries end up [cross-talking, which
+ultimately results in a segfault][2].
+
+To solve this problem, libunwind needs libgcc "front" that is, link the
+necessary functions from compiler-rt and libunwind into an archive and shared
+object that advertise themselves as ``libgcc.a``, ``libgcc_eh.a``, and
+``libgcc_s.so``, so that glibc’s baked calls are diverted to the correct objects
+in memory. Fortunately for us, compiler-rt and libunwind use the same ABI as the
+libgcc family, so the problem is solvable at the llvm-project configuration
+level: no program source needs to be edited. Thus, the end result is for a
+distro manager to configure their LLVM build with a flag that indicates they
+want to archive compiler-rt/unwind as libgcc. We achieve this by compiling
+libunwind with all the symbols necessary for compiler-rt to emulate the libgcc
+family, and then generate symlinks named for our "libgcc" that point to their
+corresponding libunwind counterparts.
+
+.. _alternatives
+
+Alternatives
+============
+
+We alternatively considered patching glibc so that the source doesn't directly
+refer to libgcc, but rather _defaults_ to libgcc, so that a system preferring
+compiler-rt/libunwind can point to these libraries at the config stage instead.
+Even if we modified the Linux standard base, this alternative won't work because
+binaries that are built using libgcc will still end up having cross-talk between
+the differing implementations.
+
+.. _target audience:
+
+Target audience
+===============
+
+llvm-libgcc is not for the casual LLVM user. It is intended to be used by distro
+managers who want to replace libgcc with compiler-rt and libunwind, but cannot
+fully abandon the libgcc family (e.g. because they are dependent on glibc). Such
+managers must have worked out their compatibility requirements ahead of using
+llvm-libgcc.
+
+.. _cmake options:
+
+CMake options
+=============
+
+.. option:: `LLVM_LIBGCC_TARGET`
+
+  **Required**
+
+  The target for which llvm-libgcc is being built. This can't be inferred from
+  ``LLVM_TARGETS_TO_BUILD``, and presently only supports one target at a time.
+
+.. option:: `LLVM_LIBGCC_SYSROOT`
+
+  **Default value**: ``${CMAKE_INSTALL_PREFIX}``
+
+  Transforms an absolute path into a relative path starting from the specified
+  directory. This variable is only used when performing an out-of-tree build.
+
+.. option:: `LLVM_LIBGCC_COMPILER_RT_INSTALL_DIRECTORY`
+
+  Path to compiler-rt. Overrides building compiler-rt in-tree, and is required
+  when building out-of-tree when ``CMAKE_CXX_COMPILER`` isn't Clang.
+
+The following CMake options are not used by llvm-libgcc but are required when
+building in-tree.
+
+.. option:: `COMPILER_RT_BUILD_BUILTINS=On`
+
+.. option:: `COMPILER_RT_BUILTINS_HIDE_SYMBOLS=Off`
+
+  Necessary for exposing symbols that libgcc_s exposes, but compiler-rt doesn't
+  by default. This variable should be set when building libunwind out-of-tree
+  too.
+
+.. option:: `LIBUNWIND_USE_COMPILER_RT=On`
+
+.. option:: `LIBUNWIND_INSTALL_SHARED_LIBRARY`
+
+  llvm-libgcc generates both `libunwind.so` and `libgcc_s.so`, so we want to
+  avoid having libunwind generate this too (otherwise there would be a clash).
+  This variable should be set when building libunwind out-of-tree too.
+
+.. _building llvm-libgcc out of tree
+
+Building llvm-libgcc out of tree
+================================
+
+Building llvm-libgcc out of tree requires a compiler that supports compiler-rt
+when its builtin symbols are exported. This usually means having two build trees
+instead of the usual one.
+
+.. code-block:: bash
+
+  # Assumes $(PWD) is /path/to/llvm-project
+  $ mkdir -p build
+  $ cd build
+
+.. _Building Clang
+
+Building Clang
+--------------
+
+The first build tree is a mostly conventional build tree and gets you a Clang
+build with these compiler-rt symbols exposed.
+
+.. code-block:: bash
+  # Assumes $(PWD) is /path/to/llvm-project
+  $ cmake -GNinja -S llvm -B build-primary                \
+      -DCMAKE_BUILD_TYPE=Release                          \
+      -DCMAKE_INSTALL_PREFIX=/tmp/llvm-libgcc-experiment  \
+      -DLLVM_ENABLE_PROJECTS='clang;compiler-rt'          \
+      -DLLVM_ENABLE_RUNTIMES='libcxx;libcxxabi;libunwind' \
+      -DCOMPILER_RT_BUILTINS_HIDE_SYMBOLS=Off             \
+      -DLIBUNWIND_INSTALL_SHARED_LIBRARY=Off              \
+      -DLIBUNWIND_ENABLE_SHARED=Off                       \
+      -DLIBUNWIND_USE_COMPILER_RT=On                      \
+      -DLIBUNWIND_HAS_COMMENT_LIB_PRAGMA=Off              \
+      -DLIBUNWIND_HAS_DL_LIB=Off                          \
+      -DLIBUNWIND_HAS_PTHREAD_LIB=Off
+  $ ninja -C build-primary install
+
+``LIBUNWIND_HAS_COMMENT_LIB_PRAGMA``, ``LIBUNWIND_HAS_DL_LIB``, and
+``LIBUNWIND_HAS_PTHREAD_LIB`` are not strictly necessary, but are useful to
+prevent requiring your libunwind dependents to also link with libdl and
+libpthread.
+
+.. _Building llvm-libgcc
+
+Building llvm-libgcc
+------------------
+
+Now that we've built the prerequisites, we can build llvm-libgcc in a second
+tree. We build llvm-libgcc for x86_64 in this example, but it's possible to
+replicate for any architecture that has a `version script`_ in the
+``version-scripts`` directory (presently i686, x86_64, armhf, and aarch64).
+
+.. _version script: https://sourceware.org/binutils/docs/ld/VERSION.html
+
+.. code-block:: bash
+
+  # Assumes $(PWD) is /path/to/llvm-project
+  $ export LLVM_LIBGCC_SYSROOT=/tmp/llvm-libgcc-experiment
+  $ export CC="${LLVM_LIBGCC_SYSROOT}/bin/clang" CXX="${LLVM_LIBGCC_SYSROOT}/bin/clang++"
+  $ cmake -GNinja -S llvm/tools/llvm-libgcc -B build-libgcc                             \
+      -DCMAKE_BUILD_TYPE=Release                                                        \
+      -DCMAKE_INSTALL_PREFIX="${LLVM_LIBGCC_SYSROOT}"                                   \
+      -DLLVM_LIBGCC_TARGET=x86_64                                                       \
+      -DLLVM_LIBGCC_LIBUNWIND_DIR="${LLVM_LIBGCC_SYSROOT}/lib/x86_64-unknown-linux-gnu"
+  $ ninja -C build-libgcc install
+
+``${LLVM_LIBGCC_SYSROOT}/lib/x86_64-unknown-linux-gnu`` is the path to
+``libunwind.a``. The target triple is determined by setting the flag
+``LLVM_RUNTIME_TARGETS`` in the Clang build: make sure they match.
+``LLVM_LIBGCC_TARGET`` is usually only the first part of the triple: ``x86_64``,
+``armv7a``, ``aarch64``, etc.
+
+## Verifying your results
+
+This gets you a copy of libunwind with the libgcc symbols. You can verify this
+using ``readelf``.
+
+.. code-block:: bash
+
+  $ readelf -W --dyn-syms "${LLVM_LIBGCC_SYSROOT}/lib/libunwind.so" | grep FUNC | grep GCC_3.0
+
+
+Roughly sixty symbols should appear, all suffixed with ``@@GCC_3.0``. You can
+replace ``GCC_3.0`` with any of the supported version names in the version
+script you’re exporting to verify that the symbols are exported.
+
+Generating a new version script
+===============================
+
+To generate a new version script, we need to generate the list of symbols that exist in the set
+(compiler-rt builtins ∪ ``libunwind.a``) ∩ ``libgcc_s.so.1``. The prerequisites for generating
+a version script are a binaries for the three aforementioned libraries targeting your architecture
+(without having built llvm-libgcc).
+
+Once these libraries are in place, to generate a new version script, run the following command.
+
+.. code-block:: bash
+
+  /path/to/llvm-project $ llvm/tools/llvm-libgcc/generate_version_script.py         \
+                              --compiler_rt=/path/to/libclang_rt.builtins-${ARCH}.a \
+                              --libunwind=/path/to/libunwind.a                      \
+                              --libgcc_s=/path/to/libgcc_s.so.1                     \
+                              --output=${ARCH}
+
+This will generate a new version script called ``gcc_s-${ARCH}.ver`` in the ``version-scripts``
+directory.
diff --git a/llvm/tools/llvm-libgcc/lib/CMakeLists.txt b/llvm/tools/llvm-libgcc/lib/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/lib/CMakeLists.txt
@@ -0,0 +1,60 @@
+include(CheckLibraryExists)
+
+add_library(unwind_shared SHARED blank.c)
+add_dependencies(unwind_shared always_run_target)
+set_target_properties(unwind_shared
+  PROPERTIES
+    LINKER_LANGUAGE C
+    OUTPUT_NAME "unwind"
+    VERSION "1.0"
+    SOVERSION "1"
+    POSITION_INDEPENDENT_CODE ON)
+target_link_options(
+  unwind_shared PRIVATE
+  -Wl,-nostdlib
+  -Wl,--whole-archive
+  -Wl,${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/${LLVM_LIBGCC_UNWIND_STATIC}
+  -Wl,${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/${LLVM_LIBGCC_COMPILER_RT}
+  -Wl,--version-script,${CMAKE_CURRENT_BINARY_DIR}/../gcc_s.ver
+  -Wl,--no-whole-archive
+)
+check_library_exists(m sin "" LLVM_LIBGCC_HAS_LIBM)
+check_library_exists(c printf "" LLVM_LIBGCC_HAS_LIBC)
+target_link_libraries(
+  unwind_shared PRIVATE
+  $<$<BOOL:LLVM_LIBGCC_HAS_LIBM>:m>
+  $<$<BOOL:LLVM_LIBGCC_HAS_LIBC>:c>
+)
+
+add_custom_target(synth_libgcc ALL
+  DEPENDS "${LLVM_LIBGCC_SYSROOT}/lib${LLVMLIB_DIR_SUFFIX}/${LLVM_LIBGCC_COMPILER_RT}" unwind_shared
+  COMMAND ${CMAKE_COMMAND} -E create_symlink
+  "${LLVM_LIBGCC_COMPILER_RT}" "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc.a")
+add_custom_target(synth_libgcc_eh ALL
+  COMMAND ${CMAKE_COMMAND} -E create_symlink
+    "${LLVM_LIBGCC_UNWIND_STATIC}" "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_eh.a")
+add_custom_target(synth_libgcc_s ALL
+  DEPENDS unwind_shared
+  COMMAND ${CMAKE_COMMAND} -E create_symlink
+    "libunwind.so" "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_s.so")
+add_custom_target(synth_libgcc_s1 ALL
+  DEPENDS unwind_shared
+  COMMAND ${CMAKE_COMMAND} -E create_symlink
+    "libunwind.so.1" "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_s.so.1")
+
+add_custom_target(unwind
+  DEPENDS
+    unwind_shared
+    synth_libgcc
+    synth_libgcc_eh
+    synth_libgcc_s
+    synth_libgcc_s1)
+set(LLVM_LIBGCC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX} CACHE PATH "")
+install(TARGETS unwind_shared
+        LIBRARY DESTINATION "${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}" COMPONENT unwind
+        ARCHIVE DESTINATION "${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}" COMPONENT unwind
+        RUNTIME DESTINATION bin COMPONENT unwind)
+install(FILES "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc.a"      TYPE LIB)
+install(FILES "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_eh.a"   TYPE LIB)
+install(FILES "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_s.so"   TYPE LIB)
+install(FILES "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libgcc_s.so.1" TYPE LIB)
diff --git a/llvm/tools/llvm-libgcc/lib/blank.c b/llvm/tools/llvm-libgcc/lib/blank.c
new file mode 100644
diff --git a/llvm/tools/llvm-libgcc/version-scripts/32-bit.ver.in b/llvm/tools/llvm-libgcc/version-scripts/32-bit.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/32-bit.ver.in
@@ -0,0 +1,26 @@
+__ashldi3@GCC_3.0
+__ashrdi3@GCC_3.0
+__cmpdi2@GCC_3.0
+__fixdfdi@GCC_3.0
+__fixsfdi@GCC_3.0
+__fixunsdfsi@GCC_3.0
+__fixunssfsi@GCC_3.0
+__floatdidf@GCC_3.0
+__floatdisf@GCC_3.0
+__lshrdi3@GCC_3.0
+__muldi3@GCC_3.0
+__negdi2@GCC_3.0
+__ucmpdi2@GCC_3.0
+__udivmoddi4@GCC_3.0
+__clzsi2@GCC_3.4
+__ctzsi2@GCC_3.4
+__paritysi2@GCC_3.4
+__popcountsi2@GCC_3.4
+__floatundidf@GCC_4.2.0
+__floatundisf@GCC_4.2.0
+__ffssi2@GCC_4.3.0
+__divmoddi4@GCC_7.0.0
+__divdi3@GLIBC_2.0
+__moddi3@GLIBC_2.0
+__udivdi3@GLIBC_2.0
+__umoddi3@GLIBC_2.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/64-bit.ver.in b/llvm/tools/llvm-libgcc/version-scripts/64-bit.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/64-bit.ver.in
@@ -0,0 +1,31 @@
+__ashlti3@GCC_3.0
+__ashrti3@GCC_3.0
+__cmpti2@GCC_3.0
+__divti3@GCC_3.0
+__ffsti2@GCC_3.0
+__fixdfti@GCC_3.0
+__fixsfti@GCC_3.0
+__fixunssfti@GCC_3.0
+__floattidf@GCC_3.0
+__lshrti3@GCC_3.0
+__modti3@GCC_3.0
+__multi3@GCC_3.0
+__negti2@GCC_3.0
+__ucmpti2@GCC_3.0
+__udivmodti4@GCC_3.0
+__udivti3@GCC_3.0
+__umodti3@GCC_3.0
+__fixunsdfti@GCC_3.0
+__floattisf@GCC_3.0
+__clzti2@GCC_3.4
+__ctzti2@GCC_3.4
+__parityti2@GCC_3.4
+__popcountti2@GCC_3.4
+__absvti2@GCC_3.4.4
+__addvti3@GCC_3.4.4
+__mulvti3@GCC_3.4.4
+__negvti2@GCC_3.4.4
+__subvti3@GCC_3.4.4
+__floatuntidf@GCC_4.2.0
+__floatuntisf@GCC_4.2.0
+__divmodti4@GCC_7.0.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/aarch64.ver.in b/llvm/tools/llvm-libgcc/version-scripts/aarch64.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/aarch64.ver.in
@@ -0,0 +1,32 @@
+__addtf3@GCC_3.0
+__divtf3@GCC_3.0
+__eqtf2@GCC_3.0
+__extenddftf2@GCC_3.0
+__extendsftf2@GCC_3.0
+__fixtfdi@GCC_3.0
+__fixtfsi@GCC_3.0
+__fixtfti@GCC_3.0
+__fixunstfdi@GCC_3.0
+__fixunstfsi@GCC_3.0
+__fixunstfti@GCC_3.0
+__floatditf@GCC_3.0
+__floatsitf@GCC_3.0
+__floattitf@GCC_3.0
+__getf2@GCC_3.0
+__gttf2@GCC_3.0
+__letf2@GCC_3.0
+__lttf2@GCC_3.0
+__multf3@GCC_3.0
+__netf2@GCC_3.0
+__subtf3@GCC_3.0
+__trunctfdf2@GCC_3.0
+__trunctfsf2@GCC_3.0
+__powitf2@GCC_4.0.0
+__divtc3@GCC_4.0.0
+__multc3@GCC_4.0.0
+__floatunditf@GCC_4.2.0
+__floatunsitf@GCC_4.2.0
+__floatuntitf@GCC_4.2.0
+__unordtf2@GCC_4.5.0
+__deregister_frame@GLIBC_2.0
+__register_frame@GLIBC_2.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/armhf.ver.in b/llvm/tools/llvm-libgcc/version-scripts/armhf.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/armhf.ver.in
@@ -0,0 +1,107 @@
+__adddf3@GCC_3.0
+__addsf3@GCC_3.0
+__aeabi_cdcmpeq@GCC_3.5
+__aeabi_cdcmple@GCC_3.5
+__aeabi_cdrcmple@GCC_3.5
+__aeabi_cfcmpeq@GCC_3.5
+__aeabi_cfcmple@GCC_3.5
+__aeabi_cfrcmple@GCC_3.5
+__aeabi_d2f@GCC_3.5
+__aeabi_d2iz@GCC_3.5
+__aeabi_d2lz@GCC_3.5
+__aeabi_d2uiz@GCC_3.5
+__aeabi_d2ulz@GCC_3.5
+__aeabi_dadd@GCC_3.5
+__aeabi_dcmpeq@GCC_3.5
+__aeabi_dcmpge@GCC_3.5
+__aeabi_dcmpgt@GCC_3.5
+__aeabi_dcmple@GCC_3.5
+__aeabi_dcmplt@GCC_3.5
+__aeabi_dcmpun@GCC_3.5
+__aeabi_ddiv@GCC_3.5
+__aeabi_dmul@GCC_3.5
+__aeabi_dneg@GCC_3.5
+__aeabi_drsub@GCC_3.5
+__aeabi_dsub@GCC_3.5
+__aeabi_f2d@GCC_3.5
+__aeabi_f2iz@GCC_3.5
+__aeabi_f2lz@GCC_3.5
+__aeabi_f2uiz@GCC_3.5
+__aeabi_f2ulz@GCC_3.5
+__aeabi_fadd@GCC_3.5
+__aeabi_fcmpeq@GCC_3.5
+__aeabi_fcmpge@GCC_3.5
+__aeabi_fcmpgt@GCC_3.5
+__aeabi_fcmple@GCC_3.5
+__aeabi_fcmplt@GCC_3.5
+__aeabi_fcmpun@GCC_3.5
+__aeabi_fdiv@GCC_3.5
+__aeabi_fmul@GCC_3.5
+__aeabi_fneg@GCC_3.5
+__aeabi_frsub@GCC_3.5
+__aeabi_fsub@GCC_3.5
+__aeabi_i2d@GCC_3.5
+__aeabi_i2f@GCC_3.5
+__aeabi_idiv@GCC_3.5
+__aeabi_idiv0@GCC_3.5
+__aeabi_idivmod@GCC_3.5
+__aeabi_l2d@GCC_3.5
+__aeabi_l2f@GCC_3.5
+__aeabi_lasr@GCC_3.5
+__aeabi_lcmp@GCC_3.5
+__aeabi_ldiv0@GCC_3.5
+__aeabi_ldivmod@GCC_3.5
+__aeabi_llsl@GCC_3.5
+__aeabi_llsr@GCC_3.5
+__aeabi_lmul@GCC_3.5
+__aeabi_ui2d@GCC_3.5
+__aeabi_ui2f@GCC_3.5
+__aeabi_uidiv@GCC_3.5
+__aeabi_uidivmod@GCC_3.5
+__aeabi_ul2d@GCC_3.5
+__aeabi_ul2f@GCC_3.5
+__aeabi_ulcmp@GCC_3.5
+__aeabi_uldivmod@GCC_3.5
+__aeabi_unwind_cpp_pr0@GCC_3.5
+__aeabi_unwind_cpp_pr1@GCC_3.5
+__aeabi_unwind_cpp_pr2@GCC_3.5
+__divdf3@GCC_3.0
+__divsf3@GCC_3.0
+__divsi3@GCC_3.0
+__eqdf2@GCC_3.0
+__eqsf2@GCC_3.0
+__extendsfdf2@GCC_3.0
+__fixdfsi@GCC_3.0
+__fixsfsi@GCC_3.0
+__floatsidf@GCC_3.0
+__floatsisf@GCC_3.0
+__floatunsidf@GCC_4.2.0
+__floatunsisf@GCC_4.2.0
+__gedf2@GCC_3.0
+__gesf2@GCC_3.0
+__gnu_unwind_frame@GCC_3.5
+__gtdf2@GCC_3.0
+__gtsf2@GCC_3.0
+__ledf2@GCC_3.0
+__lesf2@GCC_3.0
+__ltdf2@GCC_3.0
+__ltsf2@GCC_3.0
+__modsi3@GCC_3.0
+__muldf3@GCC_3.0
+__mulsf3@GCC_3.0
+__nedf2@GCC_3.0
+__negdf2@GCC_3.0
+__negsf2@GCC_3.0
+__nesf2@GCC_3.0
+__subdf3@GCC_3.0
+__subsf3@GCC_3.0
+__truncdfsf2@GCC_3.0
+__udivsi3@GCC_3.0
+__umodsi3@GCC_3.0
+__unorddf2@GCC_3.3.4
+__unordsf2@GCC_3.3.4
+_Unwind_Complete@GCC_3.5
+_Unwind_VRS_Get@GCC_3.5
+_Unwind_VRS_Pop@GCC_3.5
+_Unwind_VRS_Set@GCC_3.5
+_Unwind_Backtrace@GCC_4.3.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/common.ver.in b/llvm/tools/llvm-libgcc/version-scripts/common.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/common.ver.in
@@ -0,0 +1,39 @@
+__absvdi2@GCC_3.0
+__absvsi2@GCC_3.0
+__addvdi3@GCC_3.0
+__addvsi3@GCC_3.0
+__clear_cache@GCC_3.0
+__ffsdi2@GCC_3.0
+__fixunsdfdi@GCC_3.0
+__fixunssfdi@GCC_3.0
+__mulvdi3@GCC_3.0
+__mulvsi3@GCC_3.0
+__negvdi2@GCC_3.0
+__negvsi2@GCC_3.0
+__subvdi3@GCC_3.0
+__subvsi3@GCC_3.0
+_Unwind_DeleteException@GCC_3.0
+_Unwind_ForcedUnwind@GCC_3.0
+_Unwind_GetDataRelBase@GCC_3.0
+_Unwind_GetLanguageSpecificData@GCC_3.0
+_Unwind_GetRegionStart@GCC_3.0
+_Unwind_GetTextRelBase@GCC_3.0
+_Unwind_RaiseException@GCC_3.0
+_Unwind_Resume@GCC_3.0
+_Unwind_GetCFA@GCC_3.3
+_Unwind_Resume_or_Rethrow@GCC_3.3
+__gcc_personality_v0@GCC_3.3.1
+__clzdi2@GCC_3.4
+__ctzdi2@GCC_3.4
+__paritydi2@GCC_3.4
+__popcountdi2@GCC_3.4
+__enable_execute_stack@GCC_3.4.2
+__divdc3@GCC_4.0.0
+__divsc3@GCC_4.0.0
+__muldc3@GCC_4.0.0
+__mulsc3@GCC_4.0.0
+__powidf2@GCC_4.0.0
+__powisf2@GCC_4.0.0
+__bswapdi2@GCC_4.3.0
+__bswapsi2@GCC_4.3.0
+__emutls_get_address@GCC_4.3.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/generate_version_script.py b/llvm/tools/llvm-libgcc/version-scripts/generate_version_script.py
new file mode 100755
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/generate_version_script.py
@@ -0,0 +1,71 @@
+#!/usr/bin/python
+
+import argparse
+from collections import OrderedDict
+import os
+import sys
+
+
+def read_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--target', type=str, required=True)
+    target = parser.parse_args().target
+    target_prefix = target.split('-')[0] if not target.startswith(
+        'arm-') and not target.endswith('-gnueabihf') else 'armhf'
+    choices = ['aarch64', 'armhf', 'i386', 'x86_64']
+    if target_prefix not in choices:
+        print(f'--target must be one of {choices}, but we got {target}',
+              file=sys.stderr)
+        sys.exit(1)
+    return target_prefix
+
+
+def read(template, mappings):
+    path = f'{os.path.dirname(os.path.realpath(__file__))}/{template}.ver.in'
+    with open(path, 'r') as f:
+        for line in f:
+            line = line.strip()
+            symbol, version = line.split('@')
+            if version not in mappings:
+                mappings[version] = set([])
+            mappings[version].add(symbol)
+    return mappings
+
+
+def generate_mapping(target):
+    mapping = read('common', {'GCC_3.0': set([])})
+    mapping = read(target, mapping)
+
+    if target == 'aarch64' or target == 'x86_64':
+        mapping = read('64-bit', mapping)
+    elif target == 'armhf' or target == 'i386':
+        mapping = read('32-bit', mapping)
+
+    if target == 'i386' or target == 'x86_64':
+        mapping = read('x86', mapping)
+
+    if target != 'armhf':
+        mapping = read('non-armhf', mapping)
+    return mapping
+
+
+def generate_version_script(mapping):
+    version_script = str()
+    for (version, symbols) in mapping.items():
+        version_script += f'{version} {{\n'
+        sorted_symbols = sorted(symbols)
+        for symbol in sorted_symbols:
+            version_script += f'  {symbol};\n'
+        version_script += '};\n\n'
+    return version_script
+
+
+def main():
+    mapping = OrderedDict(sorted(generate_mapping(read_args()).items()))
+    version_script = generate_version_script(mapping)
+    with open('gcc_s.ver', 'w') as f:
+        f.write(version_script)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/llvm/tools/llvm-libgcc/version-scripts/i386.ver.in b/llvm/tools/llvm-libgcc/version-scripts/i386.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/i386.ver.in
@@ -0,0 +1,10 @@
+__register_frame_info@GLIBC_2.0
+__register_frame_info_table@GLIBC_2.0
+__register_frame_table@GLIBC_2.0
+__deregister_frame_info@GLIBC_2.0
+__fixunsxfsi@GCC_3.0
+__fixxfdi@GCC_3.0
+__floatdixf@GCC_3.0
+__floatundixf@GCC_4.2.0
+__deregister_frame@GLIBC_2.0
+__register_frame@GLIBC_2.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/non-armhf.ver.in b/llvm/tools/llvm-libgcc/version-scripts/non-armhf.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/non-armhf.ver.in
@@ -0,0 +1,8 @@
+_Unwind_Find_FDE@GCC_3.0
+_Unwind_GetGR@GCC_3.0
+_Unwind_GetIP@GCC_3.0
+_Unwind_SetGR@GCC_3.0
+_Unwind_SetIP@GCC_3.0
+_Unwind_Backtrace@GCC_3.3
+_Unwind_FindEnclosingFunction@GCC_3.3
+_Unwind_GetIPInfo@GCC_4.2.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/x86.ver.in b/llvm/tools/llvm-libgcc/version-scripts/x86.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/x86.ver.in
@@ -0,0 +1,8 @@
+__deregister_frame_info_bases@GCC_3.0
+__fixunsxfdi@GCC_3.0
+__register_frame_info_bases@GCC_3.0
+__register_frame_info_table_bases@GCC_3.0
+__divxc3@GCC_4.0.0
+__mulxc3@GCC_4.0.0
+__powixf2@GCC_4.0.0
+__cpu_indicator_init@GCC_4.8.0
diff --git a/llvm/tools/llvm-libgcc/version-scripts/x86_64.ver.in b/llvm/tools/llvm-libgcc/version-scripts/x86_64.ver.in
new file mode 100644
--- /dev/null
+++ b/llvm/tools/llvm-libgcc/version-scripts/x86_64.ver.in
@@ -0,0 +1,12 @@
+__register_frame_info@GCC_3.0
+__register_frame_info_table@GCC_3.0
+__register_frame_table@GCC_3.0
+__deregister_frame@GCC_3.0
+__deregister_frame_info@GCC_3.0
+__register_frame@GCC_3.0
+__fixunsxfti@GCC_3.0
+__fixxfti@GCC_3.0
+__floattixf@GCC_3.0
+__floatuntixf@GCC_4.2.0
+__divtc3@GCC_4.3.0
+__multc3@GCC_4.3.0