Index: compiler-rt/CMakeLists.txt
===================================================================
--- compiler-rt/CMakeLists.txt
+++ compiler-rt/CMakeLists.txt
@@ -112,9 +112,6 @@
 # COMPILER_RT_DEBUG_PYBOOL is used by lit.common.configured.in.
 pythonize_bool(COMPILER_RT_DEBUG)
 
-include(HandleCompilerRT)
-include(config-ix)
-
 if(APPLE AND SANITIZER_MIN_OSX_VERSION AND SANITIZER_MIN_OSX_VERSION VERSION_LESS "10.9")
   # Mac OS X prior to 10.9 had problems with exporting symbols from
   # libc++/libc++abi.
@@ -123,7 +120,7 @@
   set(cxxabi_supported ON)
 endif()
 
-option(SANITIZER_ALLOW_CXXABI "Allow use of C++ ABI details in ubsan" ON)
+option(SANITIZER_ALLOW_CXXABI "Allow use of C++ ABI details in sanitizers" ON)
 
 set(SANITIZE_CAN_USE_CXXABI OFF)
 if (cxxabi_supported AND SANITIZER_ALLOW_CXXABI)
@@ -131,47 +128,53 @@
 endif()
 pythonize_bool(SANITIZER_CAN_USE_CXXABI)
 
+check_link_libraries(cxx_link_libraries)
+
 set(SANITIZER_CXX_ABI "default" CACHE STRING
     "Specify C++ ABI library to use.")
-set(CXXABIS none default libcxxabi libstdc++ libc++)
+set(CXXABIS none default libc++ libc++abi libstdc++)
 set_property(CACHE SANITIZER_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
 
 if (SANITIZER_CXX_ABI STREQUAL "default")
-  if (HAVE_LIBCXXABI AND COMPILER_RT_DEFAULT_TARGET_ONLY)
-    set(SANITIZER_CXX_ABI_LIBNAME "libcxxabi")
-    set(SANITIZER_CXX_ABI_INTREE 1)
-  elseif (APPLE)
-    set(SANITIZER_CXX_ABI_LIBNAME "libcxxabi")
+  if(APPLE)
+    set(SANITIZER_CXX_ABI_LIBNAME "libc++")
     set(SANITIZER_CXX_ABI_SYSTEM 1)
-  else()
+  elseif("stdc++" IN_LIST cxx_link_libraries)
     set(SANITIZER_CXX_ABI_LIBNAME "libstdc++")
+    set(SANITIZER_CXX_ABI_SYSTEM 1)
+  elseif("c++abi" IN_LIST cxx_link_libraries)
+    set(SANITIZER_CXX_ABI_LIBNAME "libc++abi")
+  elseif("c++" IN_LIST cxx_link_libraries)
+    set(SANITIZER_CXX_ABI_LIBNAME "libc++")
   endif()
 else()
   set(SANITIZER_CXX_ABI_LIBNAME "${SANITIZER_CXX_ABI}")
 endif()
 
-if (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libcxxabi")
-  if (SANITIZER_CXX_ABI_INTREE)
-    if (NOT LIBCXXABI_ENABLE_STATIC_UNWINDER AND (TARGET unwind_shared OR HAVE_LIBUNWIND))
-      list(APPEND SANITIZER_CXX_ABI_LIBRARY unwind_shared)
-    elseif (LIBCXXABI_ENABLE_STATIC_UNWINDER AND (TARGET unwind_static OR HAVE_LIBUNWIND))
-      list(APPEND SANITIZER_CXX_ABI_LIBRARY unwind_static)
-    endif()
-    if (NOT LIBCXX_ENABLE_STATIC_ABI_LIBRARY AND (TARGET cxxabi_shared OR HAVE_LIBCXXABI))
+if (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libc++")
+  if(SANITIZER_CXX_ABI_SYSTEM)
+    list(APPEND SANITIZER_CXX_ABI_LIBRARY "c++")
+  else()
+    if(TARGET cxxabi_shared OR (HAVE_LIBCXXABI AND NOT LIBCXX_ENABLE_STATIC_ABI_LIBRARY))
       list(APPEND SANITIZER_CXX_ABI_LIBRARY cxxabi_shared)
-    elseif (LIBCXX_ENABLE_STATIC_ABI_LIBRARY AND (TARGET cxxabi_static OR HAVE_LIBCXXABI))
+    elseif(TARGET cxxabi_shared OR (HAVE_LIBCXXABI AND LIBCXX_ENABLE_STATIC_ABI_LIBRARY))
       list(APPEND SANITIZER_CXX_ABI_LIBRARY cxxabi_static)
+    else()
+      list(APPEND SANITIZER_CXX_ABI_LIBRARY "c++")
     endif()
-  else()
-    list(APPEND SANITIZER_CXX_ABI_LIBRARY "c++abi")
   endif()
-elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libc++")
-  list(APPEND SANITIZER_CXX_ABI_LIBRARY "c++")
 elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libstdc++")
-  append_list_if(COMPILER_RT_HAS_LIBSTDCXX stdc++ SANITIZER_CXX_ABI_LIBRARY)
+  list(APPEND SANITIZER_CXX_ABI_LIBRARY "stdc++")
 endif()
 
-option(SANITIZER_USE_COMPILER_RT "Use compiler-rt builtins instead of libgcc" OFF)
+check_runtime_library(runtime_library)
+if(runtime_library MATCHES ".*libgcc.*")
+  set(COMPILER_RT_RUNTIME_LIBRARY "libgcc")
+elseif(runtime_library MATCHES ".*libclang_rt.builtins.*")
+  set(COMPILER_RT_RUNTIME_LIBRARY "compiler-rt")
+endif()
+
+include(config-ix)
 
 #================================
 # Setup Compiler Flags
@@ -319,9 +322,7 @@
 # Set common link flags.
 append_list_if(COMPILER_RT_HAS_NODEFAULTLIBS_FLAG -nodefaultlibs SANITIZER_COMMON_LINK_FLAGS)
 
-if (SANITIZER_USE_COMPILER_RT)
-  list(APPEND SANITIZER_COMMON_LINK_FLAGS -rtlib=compiler-rt)
-  find_compiler_rt_library(builtins COMPILER_RT_BUILTINS_LIBRARY)
+if (COMPILER_RT_RUNTIME_LIBRARY STREQUAL "compiler-rt")
   list(APPEND SANITIZER_COMMON_LINK_LIBS ${COMPILER_RT_BUILTINS_LIBRARY})
 else()
   if (ANDROID)
Index: compiler-rt/cmake/Modules/CompilerRTUtils.cmake
===================================================================
--- compiler-rt/cmake/Modules/CompilerRTUtils.cmake
+++ compiler-rt/cmake/Modules/CompilerRTUtils.cmake
@@ -144,8 +144,12 @@
       endif()
       set(SAVED_CMAKE_EXE_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS})
       set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${argstring}")
+      if(SANITIZER_CXX_ABI_SYSTEM)
+        set(FLAG_LINK_LIBRARIES ${SANITIZER_CXX_ABI_LIBRARY})
+      endif()
       try_compile(CAN_TARGET_${arch} ${CMAKE_BINARY_DIR} ${SIMPLE_SOURCE}
                   COMPILE_DEFINITIONS "${TARGET_${arch}_CFLAGS} ${FLAG_NO_EXCEPTIONS}"
+                  LINK_LIBRARIES ${FLAG_LINK_LIBRARIES}
                   OUTPUT_VARIABLE TARGET_${arch}_OUTPUT)
       set(CMAKE_EXE_LINKER_FLAGS ${SAVED_CMAKE_EXE_LINKER_FLAGS})
     endif()
@@ -314,3 +318,58 @@
   endforeach ()
   set(${output_var} ${intermediate} PARENT_SCOPE)
 endfunction()
+
+function(check_runtime_library variable)
+  set(COMPILER_COMMAND ${CMAKE_CXX_COMPILER} ${SANITIZER_COMMON_CFLAGS}
+      "--print-libgcc-file-name")
+  if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
+    list(APPEND COMPILER_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
+  endif()
+  execute_process(
+      COMMAND ${COMPILER_COMMAND}
+      RESULT_VARIABLE COMMAND_RESULT
+      OUTPUT_VARIABLE LIBRARY_FILE
+  )
+  string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
+  if(COMMAND_RESULT EQUAL 0)
+    set(${variable} "${LIBRARY_FILE}" PARENT_SCOPE)
+  endif()
+endfunction()
+
+function(check_link_libraries variable)
+  set(COMPILER_COMMAND "${CMAKE_CXX_COMPILER}" "${SANITIZER_COMMON_CFLAGS}"
+    "${CMAKE_ROOT}/Modules/DummyCXXFile.cxx" "-###")
+  if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
+    list(APPEND COMPILER_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
+  endif()
+  execute_process(
+      COMMAND ${COMPILER_COMMAND}
+      RESULT_VARIABLE COMMAND_RESULT
+      ERROR_VARIABLE COMMAND_OUTPUT
+  )
+  if(COMMAND_RESULT EQUAL 0)
+    get_filename_component(linker ${CMAKE_LINKER} NAME)
+    string(REGEX REPLACE "([][+.*?()^$])" "\\\\\\1" linker "${linker}")
+    set(LINKER_REGEX "^( *|.*[/\\])(${linker}|([^/\\]+-)?ld|collect2)[^/\\]*( |$)")
+    set(EXCLUDE_REGEX "collect2 version |^[A-Za-z0-9_]+=")
+    string(REGEX REPLACE "\r?\n" ";" output_lines "${COMMAND_OUTPUT}")
+    foreach(line IN LISTS output_lines)
+      if(line MATCHES "${LINKER_REGEX}" AND NOT line MATCHES "${EXCLUDE_REGEX}")
+        separate_arguments(args NATIVE_COMMAND "${line}")
+        list(GET args 0 cmd)
+      endif()
+      if("${cmd}" MATCHES "${LINKER_REGEX}")
+        foreach(arg IN LISTS args)
+          if("${arg}" MATCHES "^-l([^:].*)$")
+            set(lib "${CMAKE_MATCH_1}")
+            list(APPEND libs ${lib})
+          elseif("${arg}" MATCHES "^(.:)?[/\\].*\\.a$")
+            list(APPEND libs ${arg})
+          endif()
+        endforeach()
+        break()
+      endif()
+    endforeach()
+    set(${variable} "${libs}" PARENT_SCOPE)
+  endif()
+endfunction()
Index: compiler-rt/cmake/Modules/HandleCompilerRT.cmake
===================================================================
--- compiler-rt/cmake/Modules/HandleCompilerRT.cmake
+++ compiler-rt/cmake/Modules/HandleCompilerRT.cmake
@@ -1,5 +1,4 @@
-function(find_compiler_rt_library name dest)
-  set(dest "" PARENT_SCOPE)
+function(find_compiler_rt_library name variable)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${SANITIZER_COMMON_CFLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
@@ -14,7 +13,7 @@
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_FILE}")
     message(STATUS "Found compiler-rt ${name} library: ${LIBRARY_FILE}")
-    set(${dest} "${LIBRARY_FILE}" PARENT_SCOPE)
+    set(${variable} "${LIBRARY_FILE}" PARENT_SCOPE)
   else()
     message(STATUS "Failed to find compiler-rt ${name} library")
   endif()
Index: compiler-rt/cmake/config-ix.cmake
===================================================================
--- compiler-rt/cmake/config-ix.cmake
+++ compiler-rt/cmake/config-ix.cmake
@@ -13,7 +13,10 @@
 endfunction()
 
 check_library_exists(c fopen "" COMPILER_RT_HAS_LIBC)
-if (NOT SANITIZER_USE_COMPILER_RT)
+if (COMPILER_RT_RUNTIME_LIBRARY STREQUAL "compiler-rt")
+  include(HandleCompilerRT)
+  find_compiler_rt_library(builtins COMPILER_RT_BUILTINS_LIBRARY)
+else()
   if (ANDROID)
     check_library_exists(gcc __gcc_personality_v0 "" COMPILER_RT_HAS_GCC_LIB)
   else()
@@ -27,9 +30,7 @@
   if (COMPILER_RT_HAS_LIBC)
     list(APPEND CMAKE_REQUIRED_LIBRARIES c)
   endif ()
-  if (SANITIZER_USE_COMPILER_RT)
-    list(APPEND CMAKE_REQUIRED_FLAGS -rtlib=compiler-rt)
-    find_compiler_rt_library(builtins COMPILER_RT_BUILTINS_LIBRARY)
+  if (COMPILER_RT_RUNTIME_LIBRARY STREQUAL "compiler-rt")
     list(APPEND CMAKE_REQUIRED_LIBRARIES "${COMPILER_RT_BUILTINS_LIBRARY}")
   elseif (COMPILER_RT_HAS_GCC_S_LIB)
     list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
@@ -125,7 +126,7 @@
 # platform. We use the results of these tests to build only the various target
 # runtime libraries supported by our current compilers cross-compiling
 # abilities.
-set(SIMPLE_SOURCE ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/simple.cc)
+set(SIMPLE_SOURCE ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/simple.c)
 file(WRITE ${SIMPLE_SOURCE} "#include <stdlib.h>\n#include <stdio.h>\nint main() { printf(\"hello, world\"); }\n")
 
 # Detect whether the current target platform is 32-bit or 64-bit, and setup