diff --git a/clang/lib/Basic/CMakeLists.txt b/clang/lib/Basic/CMakeLists.txt
--- a/clang/lib/Basic/CMakeLists.txt
+++ b/clang/lib/Basic/CMakeLists.txt
@@ -17,6 +17,11 @@
 if(clang_vc AND LLVM_APPEND_VC_REV)
   set(clang_source_dir ${CLANG_SOURCE_DIR})
 endif()
+if (CLANG_VC_REPOSITORY AND CLANG_VC_REVISION)
+  set(clang_source_dir ${CLANG_SOURCE_DIR})
+  set(clang_vc_repository ${CLANG_VC_REPOSITORY})
+  set(clang_vc_revision ${CLANG_VC_REVISION})
+endif()
 
 # Create custom target to generate the VC revision include.
 add_custom_command(OUTPUT "${version_inc}"
@@ -24,6 +29,8 @@
   COMMAND ${CMAKE_COMMAND} "-DNAMES=\"LLVM;CLANG\""
                            "-DLLVM_SOURCE_DIR=${llvm_source_dir}"
                            "-DCLANG_SOURCE_DIR=${clang_source_dir}"
+                           "-DCLANG_VC_REPOSITORY=${clang_vc_repository}"
+                           "-DCLANG_VC_REVISION=${clang_vc_revision}"
                            "-DHEADER_FILE=${version_inc}"
                            -P "${generate_vcs_version_script}")
 
diff --git a/llvm/cmake/modules/GenerateVersionFromVCS.cmake b/llvm/cmake/modules/GenerateVersionFromVCS.cmake
--- a/llvm/cmake/modules/GenerateVersionFromVCS.cmake
+++ b/llvm/cmake/modules/GenerateVersionFromVCS.cmake
@@ -18,9 +18,11 @@
 # Handle strange terminals
 set(ENV{TERM} "dumb")
 
-function(append_info name path)
-  if(path)
-    get_source_info("${path}" revision repository)
+function(append_info name path repository revision)
+  if (NOT repository AND NOT revision)
+    if(path)
+      get_source_info("${path}" revision repository)
+    endif()
   endif()
   if(revision)
     file(APPEND "${HEADER_FILE}.tmp"
@@ -39,10 +41,14 @@
 endfunction()
 
 foreach(name IN LISTS NAMES)
-  if(NOT DEFINED ${name}_SOURCE_DIR)
-    message(FATAL_ERROR "${name}_SOURCE_DIR is not defined")
+  if(${name}_VC_REPOSITORY AND ${name}_VC_REVISION)
+    append_info(${name} "" "${${name}_VC_REPOSITORY}" "${${name}_VC_REVISION}")
+  else()
+    if(NOT DEFINED ${name}_SOURCE_DIR)
+      message(FATAL_ERROR "${name}_SOURCE_DIR is not defined")
+    endif()
+    append_info(${name} "${${name}_SOURCE_DIR}" "" "")
   endif()
-  append_info(${name} "${${name}_SOURCE_DIR}")
 endforeach()
 
 # Copy the file only if it has changed.