Index: cfe/trunk/CMakeLists.txt
===================================================================
--- cfe/trunk/CMakeLists.txt
+++ cfe/trunk/CMakeLists.txt
@@ -595,18 +595,24 @@
   add_subdirectory(docs)
 endif()
 
-if(EXISTS "${CMAKE_CURRENT_BINARY_DIR}/clang.order")
-  file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/clang.order")
-endif()
-
-if(CLANG_ORDER_FILE STREQUAL "${CMAKE_CURRENT_BINARY_DIR}/clang.order")
+# this line is needed as a cleanup to ensure that any CMakeCaches with the old
+# default value get updated to the new default.
+if(CLANG_ORDER_FILE STREQUAL "")
   unset(CLANG_ORDER_FILE CACHE)
-  unset(CLANG_ORDER_FILE)
 endif()
 
-set(CLANG_ORDER_FILE "" CACHE FILEPATH
+set(CLANG_ORDER_FILE ${CMAKE_CURRENT_BINARY_DIR}/clang.order CACHE FILEPATH
   "Order file to use when compiling clang in order to improve startup time.")
 
+if(CLANG_ORDER_FILE AND NOT EXISTS ${CLANG_ORDER_FILE})
+  string(FIND CLANG_ORDER_FILE "${CMAKE_CURRENT_BINARY_DIR}" PATH_START)
+  if(PATH_START EQUAL 0)
+    file(WRITE ${CLANG_ORDER_FILE} "\n")
+  else()
+    message(FATAL_ERROR "Specified order file '${CLANG_ORDER_FILE}' does not exist.")
+  endif()
+endif()
+
 if (CLANG_BUILT_STANDALONE OR CMAKE_VERSION VERSION_EQUAL 3 OR
     CMAKE_VERSION VERSION_GREATER 3)
   # Generate a list of CMake library targets so that other CMake projects can
Index: cfe/trunk/tools/driver/CMakeLists.txt
===================================================================
--- cfe/trunk/tools/driver/CMakeLists.txt
+++ cfe/trunk/tools/driver/CMakeLists.txt
@@ -87,8 +87,24 @@
   set(TOOL_INFO_BUILD_VERSION)
 endif()
 
-if(CLANG_ORDER_FILE AND EXISTS CLANG_ORDER_FILE)
-  target_link_libraries(clang "-Wl,-order_file,${CLANG_ORDER_FILE}")
+if(CLANG_ORDER_FILE)
+  include(CMakePushCheckState)
+
+  function(check_linker_flag flag out_var)
+    cmake_push_check_state()
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${flag}")
+    check_cxx_compiler_flag("" ${out_var})
+    cmake_pop_check_state()
+  endfunction()
+
+  # This is a test to ensure the actual order file works with the linker.
+  check_linker_flag("-Wl,-order_file,${CLANG_ORDER_FILE}"
+    LINKER_ORDER_FILE_WORKS)
+  
+  if(LINKER_ORDER_FILE_WORKS)
+    target_link_libraries(clang "-Wl,-order_file,${CLANG_ORDER_FILE}")
+    set_target_properties(clang PROPERTIES LINK_DEPENDS ${CLANG_ORDER_FILE})
+  endif()
 endif()
 
 if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
Index: cfe/trunk/utils/perf-training/CMakeLists.txt
===================================================================
--- cfe/trunk/utils/perf-training/CMakeLists.txt
+++ cfe/trunk/utils/perf-training/CMakeLists.txt
@@ -55,9 +55,8 @@
     COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py clean ${CMAKE_CURRENT_BINARY_DIR} dtrace
     COMMENT "Clearing old dtrace data")
 
-
   add_custom_target(generate-order-file
-    COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py gen-order-file --binary $<TARGET_FILE:clang> --output ${CMAKE_CURRENT_BINARY_DIR}/clang.order ${CMAKE_CURRENT_BINARY_DIR}
+    COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py gen-order-file --binary $<TARGET_FILE:clang> --output ${CLANG_ORDER_FILE} ${CMAKE_CURRENT_BINARY_DIR}
     COMMENT "Generating order file"
     DEPENDS generate-dtrace-logs)
 endif()