Index: clang/cmake/caches/Fuchsia-stage2.cmake
===================================================================
--- clang/cmake/caches/Fuchsia-stage2.cmake
+++ clang/cmake/caches/Fuchsia-stage2.cmake
@@ -74,6 +74,9 @@
     set(RUNTIMES_${target}_SANITIZER_CXX_ABI "libc++" CACHE STRING "")
     set(RUNTIMES_${target}_SANITIZER_CXX_ABI_INTREE ON CACHE BOOL "")
     set(RUNTIMES_${target}_COMPILER_RT_USE_BUILTINS_LIBRARY ON CACHE BOOL "")
+
+    # Use .build-id link.
+    list(APPEND RUNTIME_BUILD_ID_LINK "${target}")
   endif()
 endforeach()
 
@@ -126,6 +129,9 @@
     set(RUNTIMES_${target}-fuchsia_LIBCXX_HERMETIC_STATIC_LIBRARY ON CACHE BOOL "")
     set(RUNTIMES_${target}-fuchsia_LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY OFF CACHE BOOL "")
     set(RUNTIMES_${target}-fuchsia_LIBCXX_ABI_VERSION 2 CACHE STRING "")
+
+    # Use .build-id link.
+    list(APPEND RUNTIME_BUILD_ID_LINK "${target}-fuchsia")
   endforeach()
 
   set(LLVM_RUNTIME_SANITIZERS "Address" CACHE STRING "")
@@ -134,6 +140,7 @@
 
 set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")
 set(LLVM_RUNTIME_TARGETS "${RUNTIME_TARGETS}" CACHE STRING "")
+set(LLVM_RUNTIME_BUILD_ID_LINK_TARGETS "${RUNTIME_BUILD_ID_LINK}" CACHE STRING "")
 
 # Setup toolchain.
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")
Index: llvm/cmake/modules/LLVMExternalProjectUtils.cmake
===================================================================
--- llvm/cmake/modules/LLVMExternalProjectUtils.cmake
+++ llvm/cmake/modules/LLVMExternalProjectUtils.cmake
@@ -35,12 +35,14 @@
 #     Extra targets in the subproject to generate targets for
 #   PASSTHROUGH_PREFIXES prefix...
 #     Extra variable prefixes (name is always included) to pass down
+#   STRIP_TOOL path
+#     Use provided strip tool instead of the default one.
 #   )
 function(llvm_ExternalProject_Add name source_dir)
   cmake_parse_arguments(ARG
     "USE_TOOLCHAIN;EXCLUDE_FROM_ALL;NO_INSTALL;ALWAYS_CLEAN"
     "SOURCE_DIR"
-    "CMAKE_ARGS;TOOLCHAIN_TOOLS;RUNTIME_LIBRARIES;DEPENDS;EXTRA_TARGETS;PASSTHROUGH_PREFIXES"
+    "CMAKE_ARGS;TOOLCHAIN_TOOLS;RUNTIME_LIBRARIES;DEPENDS;EXTRA_TARGETS;PASSTHROUGH_PREFIXES;STRIP_TOOL"
     ${ARGN})
   canonicalize_tool_name(${name} nameCanon)
   if(NOT ARG_TOOLCHAIN_TOOLS)
@@ -125,12 +127,16 @@
     if(llvm-objcopy IN_LIST TOOLCHAIN_TOOLS)
       list(APPEND compiler_args -DCMAKE_OBJCOPY=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-objcopy)
     endif()
-    if(llvm-strip IN_LIST TOOLCHAIN_TOOLS)
+    if(llvm-strip IN_LIST TOOLCHAIN_TOOLS AND NOT ARG_STRIP_TOOL)
       list(APPEND compiler_args -DCMAKE_STRIP=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-strip)
     endif()
     list(APPEND ARG_DEPENDS ${TOOLCHAIN_TOOLS})
   endif()
 
+  if(ARG_STRIP_TOOL)
+    list(APPEND compiler_args -DCMAKE_STRIP=${ARG_STRIP_TOOL})
+  endif()
+
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp
     DEPENDS ${ARG_DEPENDS}
Index: llvm/runtimes/CMakeLists.txt
===================================================================
--- llvm/runtimes/CMakeLists.txt
+++ llvm/runtimes/CMakeLists.txt
@@ -318,6 +318,14 @@
     list(APPEND runtime_names ${projName})
   endforeach()
 
+  if(LLVM_RUNTIME_BUILD_ID_LINK_TARGETS)
+    configure_file(
+      ${CMAKE_CURRENT_SOURCE_DIR}/llvm-strip-link.in
+      ${CMAKE_CURRENT_BINARY_DIR}/llvm-strip-link
+      @ONLY
+    )
+  endif()
+
   function(runtime_default_target)
     cmake_parse_arguments(ARG "" "" "DEPENDS;PREFIXES" ${ARGN})
 
@@ -426,6 +434,10 @@
       endif()
     endforeach()
 
+    if(target IN_LIST LLVM_RUNTIME_BUILD_ID_LINK_TARGETS)
+        set(EXTRA_ARGS ${EXTRA_ARGS} STRIP_TOOL ${CMAKE_CURRENT_BINARY_DIR}/llvm-strip-link)
+    endif()
+
     llvm_ExternalProject_Add(runtimes-${name}
                              ${CMAKE_CURRENT_SOURCE_DIR}
                              DEPENDS ${${name}_deps}
Index: llvm/runtimes/llvm-strip-link.in
===================================================================
--- /dev/null
+++ llvm/runtimes/llvm-strip-link.in
@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import os
+import sys
+import subprocess
+
+
+ELF_MAGIC = '\x7fELF'
+
+with open(sys.argv[1], "rb") as f:
+    buf = f.read(len(ELF_MAGIC))
+    if buf != ELF_MAGIC:
+        sys.exit(0)
+
+llvm_objcopy = os.path.join('@LLVM_RUNTIME_OUTPUT_INTDIR@', 'llvm-objcopy')
+install_dir = os.path.join(os.getenv('DESTDIR', ''), '@CMAKE_INSTALL_PREFIX@')
+link_dir = os.path.join(install_dir, 'lib', 'debug', '.build-id')
+
+sys.exit(subprocess.call([
+    llvm_objcopy,
+    '--strip-sections',
+    '--build-id-link-dir=' + link_dir,
+    '--build-id-link-input=.debug',
+    '--build-id-link-output=',
+    sys.argv[1],
+]))