Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -1,14 +1,16 @@
 # CMake build for CompilerRT.
 #
 # This build assumes that CompilerRT is checked out into the
-# 'projects/compiler-rt' inside of an LLVM tree.
+# 'projects/compiler-rt' or 'runtimes/compiler-rt' inside of an LLVM tree.
 # Standalone build system for CompilerRT is not yet ready.
 #
 # An important constraint of the build is that it only produces libraries
 # based on the ability of the host toolchain to target various platforms.
 
-# Check if compiler-rt is built as a standalone project.
-if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+# Check if compiler-rt is built as a standalone project or from inside the
+# runtimes directory.
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR
+    "${CMAKE_SOURCE_DIR}/compiler-rt" STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(CompilerRT C CXX ASM)
   set(COMPILER_RT_STANDALONE_BUILD TRUE)
 endif()
Index: lib/tsan/CMakeLists.txt
===================================================================
--- lib/tsan/CMakeLists.txt
+++ lib/tsan/CMakeLists.txt
@@ -101,13 +101,6 @@
 
 if(APPLE)
   set(TSAN_ASM_SOURCES rtl/tsan_rtl_amd64.S)
-  # Xcode will try to compile this file as C ('clang -x c'), and that will fail.
-  if (${CMAKE_GENERATOR} STREQUAL "Xcode")
-    enable_language(ASM)
-  else()
-    # Pass ASM file directly to the C++ compiler.
-    set_source_files_properties(${TSAN_ASM_SOURCES} PROPERTIES LANGUAGE C)
-  endif()
   add_compiler_rt_runtime(clang_rt.tsan
     SHARED
     OS ${TSAN_SUPPORTED_OS}
@@ -138,9 +131,6 @@
   foreach(arch ${TSAN_SUPPORTED_ARCH})
     if(arch STREQUAL "x86_64")
       set(TSAN_ASM_SOURCES rtl/tsan_rtl_amd64.S)
-      # Pass ASM file directly to the C++ compiler.
-      set_source_files_properties(${TSAN_ASM_SOURCES} PROPERTIES
-        LANGUAGE C)
       # Sanity check for Go runtime.
       set(BUILDGO_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/go/buildgo.sh)
       add_custom_target(GotsanRuntimeCheck
@@ -152,19 +142,10 @@
         VERBATIM)
     elseif(arch STREQUAL "aarch64")
       set(TSAN_ASM_SOURCES rtl/tsan_rtl_aarch64.S)
-      # Pass ASM file directly to the C++ compiler.
-      set_source_files_properties(${TSAN_ASM_SOURCES} PROPERTIES
-        LANGUAGE C)
    elseif(arch MATCHES "powerpc64|powerpc64le")
      set(TSAN_ASM_SOURCES rtl/tsan_rtl_ppc64.S)
-     # Pass ASM file directly to the C++ compiler.
-     set_source_files_properties(${TSAN_ASM_SOURCES} PROPERTIES
-       LANGUAGE C)
     elseif(arch MATCHES "mips64|mips64le")
      set(TSAN_ASM_SOURCES rtl/tsan_rtl_mips64.S)
-     # Pass ASM file directly to the C++ compiler.
-     set_source_files_properties(${TSAN_ASM_SOURCES} PROPERTIES
-       LANGUAGE C)
     else()
       set(TSAN_ASM_SOURCES)
     endif()