diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index 2b67c59..02124de 100644
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -53,8 +53,10 @@ option(LIBCXXABI_ENABLE_ASSERTIONS "Enable assertions independent of build mode.
 option(LIBCXXABI_ENABLE_PEDANTIC "Compile with pedantic enabled." OFF)
 option(LIBCXXABI_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
 option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." ON)
-if (LIBCXXABI_USE_LLVM_UNWINDER AND NOT "libunwind" IN_LIST LLVM_ENABLE_RUNTIMES)
-  message(FATAL_ERROR "LIBCXXABI_USE_LLVM_UNWINDER is set to ON, but libunwind is not specified in LLVM_ENABLE_RUNTIMES.")
+if (LIBCXXABI_USE_LLVM_UNWINDER AND
+    NOT "libunwind" IN_LIST LLVM_ENABLE_RUNTIMES AND
+    NOT "llvm-libgcc" IN_LIST LLVM_ENABLE_RUNTIMES)
+  message(FATAL_ERROR "LIBCXXABI_USE_LLVM_UNWINDER is set to ON, but neither libunwind nor llvm-libgcc is specified in LLVM_ENABLE_RUNTIMES.")
 endif()
 option(LIBCXXABI_ENABLE_STATIC_UNWINDER "Statically link the LLVM unwinder." OFF)
 option(LIBCXXABI_USE_COMPILER_RT "Use compiler-rt instead of libgcc" OFF)
diff --git a/llvm-libgcc/CMakeLists.txt b/llvm-libgcc/CMakeLists.txt
index 47208fc..9f31762 100644
--- a/llvm-libgcc/CMakeLists.txt
+++ b/llvm-libgcc/CMakeLists.txt
@@ -32,8 +32,13 @@ set(LLVM_LIBGCC_LIBUNWIND_PATH "${CMAKE_CURRENT_LIST_DIR}/../libunwind"
   CACHE PATH "Specify path to libunwind source.")
 set(LLVM_LIBGCC_COMPILER_RT_PATH "${CMAKE_CURRENT_LIST_DIR}/../compiler-rt"
   CACHE PATH "Specify path to compiler-rt source.")
+option(LLVM_LIBGCC_BUILD_COMPILER_RT
+  "Build compiler-rt builtins as part of llvm-libgcc." ON)
 
 include(GNUInstallDirs)
+list(APPEND CMAKE_MODULE_PATH "${LLVM_LIBGCC_COMPILER_RT_PATH}/cmake/Modules")
+include(CompilerRTUtils)
+include(HandleCompilerRT)
 
 if(NOT LLVM_LIBGCC_EXPLICIT_OPT_IN)
   message(FATAL_ERROR
@@ -88,9 +93,11 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LLVM_LIBGCC_LIBRARY_DIR})
 # Build libraries
 #===============================================================================
 
-set(COMPILER_RT_BUILD_BUILTINS ON)
-set(COMPILER_RT_BUILTINS_HIDE_SYMBOLS OFF)
-add_subdirectory(${LLVM_LIBGCC_COMPILER_RT_PATH} ${LLVM_LIBGCC_COMPILER_RT_BINARY_DIR})
+if(LLVM_LIBGCC_BUILD_COMPILER_RT)
+  set(COMPILER_RT_BUILD_BUILTINS ON)
+  set(COMPILER_RT_BUILTINS_HIDE_SYMBOLS OFF)
+  add_subdirectory(${LLVM_LIBGCC_COMPILER_RT_PATH} ${LLVM_LIBGCC_COMPILER_RT_BINARY_DIR})
+endif()
 
 set(LIBUNWIND_ENABLE_STATIC ON)
 set(LIBUNWIND_ENABLE_SHARED ON)
@@ -108,33 +115,65 @@ add_custom_target(gcc_s.ver
 
 add_dependencies(unwind_shared gcc_s.ver)
 
+if(NOT LLVM_TARGET_TRIPLE)
+  set(LLVM_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
+endif()
 construct_compiler_rt_default_triple()
 
-target_link_options(unwind_shared PUBLIC
+target_link_options(unwind_shared PRIVATE
   -Wl,--version-script,${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver
 )
 
-target_link_libraries(unwind_shared PUBLIC
-  $<TARGET_OBJECTS:clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}>
-  m
-)
+if(LLVM_LIBGCC_BUILD_COMPILER_RT)
+  set(LLVM_LIBGCC_COMPILER_RT_DEPS clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH})
+  set(LLVM_LIBGCC_COMPILER_RT_OBJECTS
+    $<TARGET_OBJECTS:clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}>)
+else()
+  set(LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY "" CACHE FILEPATH
+    "Path to an existing compiler-rt builtins archive when LLVM_LIBGCC_BUILD_COMPILER_RT is OFF.")
+  if(NOT LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY)
+    find_compiler_rt_library(builtins LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY
+      TARGET ${COMPILER_RT_DEFAULT_TARGET_TRIPLE})
+  endif()
+  if(NOT LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY OR
+     LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY STREQUAL "NOTFOUND")
+    message(FATAL_ERROR
+      "LLVM_LIBGCC_BUILD_COMPILER_RT is OFF, but compiler-rt builtins could not "
+      "be found. Set LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY to an existing "
+      "libclang_rt.builtins archive.")
+  endif()
+  set(LLVM_LIBGCC_COMPILER_RT_LINK_TARGET
+    "${LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY}" CACHE STRING
+    "Install-tree target used by the libgcc.a symlink when LLVM_LIBGCC_BUILD_COMPILER_RT is OFF.")
+  set(LLVM_LIBGCC_COMPILER_RT_OBJECTS
+    -Wl,--whole-archive
+    ${LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY}
+    -Wl,--no-whole-archive)
+endif()
+
+target_link_libraries(unwind_shared PRIVATE ${LLVM_LIBGCC_COMPILER_RT_OBJECTS})
+target_link_libraries(unwind_shared PUBLIC m)
 
 #===============================================================================
 # Install Symlinks
 #===============================================================================
 
-get_compiler_rt_install_dir(${COMPILER_RT_DEFAULT_TARGET_ARCH} install_dir_builtins)
-string(REGEX REPLACE "^lib/" "" install_dir_builtins "${install_dir_builtins}")
-string(FIND "${install_dir_builtins}" "clang" install_path_contains_triple)
-if(install_path_contains_triple EQUAL -1)
-  set(builtins_suffix "-${COMPILER_RT_DEFAULT_TARGET_ARCH}")
+if(LLVM_LIBGCC_BUILD_COMPILER_RT)
+  get_compiler_rt_install_dir(${COMPILER_RT_DEFAULT_TARGET_ARCH} install_dir_builtins)
+  string(REGEX REPLACE "^lib/" "" install_dir_builtins "${install_dir_builtins}")
+  string(FIND "${install_dir_builtins}" "clang" install_path_contains_triple)
+  if(install_path_contains_triple EQUAL -1)
+    set(builtins_suffix "-${COMPILER_RT_DEFAULT_TARGET_ARCH}")
+  else()
+    string(PREPEND install_dir_builtins "../")
+  endif()
+  set(LLVM_LIBGCC_COMPILER_RT ${install_dir_builtins}/libclang_rt.builtins${builtins_suffix}.a)
 else()
-  string(PREPEND install_dir_builtins "../")
+  set(LLVM_LIBGCC_COMPILER_RT "${LLVM_LIBGCC_COMPILER_RT_LINK_TARGET}")
 endif()
-set(LLVM_LIBGCC_COMPILER_RT ${install_dir_builtins}/libclang_rt.builtins${builtins_suffix}.a)
 
 add_custom_target(llvm-libgcc ALL
-  DEPENDS unwind_shared unwind_static clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}
+  DEPENDS unwind_shared unwind_static ${LLVM_LIBGCC_COMPILER_RT_DEPS}
   COMMAND ${CMAKE_COMMAND} -E create_symlink ${LLVM_LIBGCC_COMPILER_RT} libgcc.a
   COMMAND ${CMAKE_COMMAND} -E create_symlink libunwind.a libgcc_eh.a
   COMMAND ${CMAKE_COMMAND} -E create_symlink libunwind.so libgcc_s.so.1.0
@@ -147,10 +186,12 @@ install(TARGETS unwind_shared unwind_static
   ARCHIVE DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR} COMPONENT llvm-libgcc
   RUNTIME DESTINATION ${LLVM_LIBGCC_INSTALL_RUNTIME_DIR} COMPONENT llvm-libgcc)
 
-install(TARGETS clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}
-  LIBRARY DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
-  ARCHIVE DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
-  RUNTIME DESTINATION ${LLVM_LIBGCC_INSTALL_RUNTIME_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc)
+if(LLVM_LIBGCC_BUILD_COMPILER_RT)
+  install(TARGETS clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}
+    LIBRARY DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
+    ARCHIVE DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
+    RUNTIME DESTINATION ${LLVM_LIBGCC_INSTALL_RUNTIME_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc)
+endif()
 
 foreach(VAR libgcc.a libgcc_eh.a libgcc_s.so.1.0 libgcc_s.so.1 libgcc_s.so)
   install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${VAR}
diff --git a/llvm-libgcc/docs/LLVMLibgcc.rst b/llvm-libgcc/docs/LLVMLibgcc.rst
index 22dae7a..88e3fa2 100644
--- a/llvm-libgcc/docs/LLVMLibgcc.rst
+++ b/llvm-libgcc/docs/LLVMLibgcc.rst
@@ -72,6 +72,18 @@ CMake options
   Since llvm-libgcc is such a fundamental, low-level component, we have made it
   difficult to accidentally build, by requiring you to set an opt-in flag.
 
+.. option:: `LLVM_LIBGCC_BUILD_COMPILER_RT`
+
+  **Default**: ``ON``
+
+  Build the compiler-rt builtins archive as part of llvm-libgcc. When set to
+  ``OFF``, llvm-libgcc finds an existing compiler-rt builtins archive with the
+  compiler driver, links it into ``libunwind.so``, and only creates the
+  compatibility symlinks instead of installing compiler-rt. Set
+  ``LLVM_LIBGCC_COMPILER_RT_BUILTINS_LIBRARY`` if the compiler driver cannot
+  find the archive, and set ``LLVM_LIBGCC_COMPILER_RT_LINK_TARGET`` if the
+  installed symlink should point at a different path.
+
 .. _Building llvm-libgcc
 
 Building llvm-libgcc