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
@@ -14,9 +14,19 @@
 if(llvm_vc AND LLVM_APPEND_VC_REV)
   set(llvm_source_dir ${LLVM_MAIN_SRC_DIR})
 endif()
+if (LLVM_VC_REPOSITORY AND LLVM_VC_REVISION)
+  set(llvm_source_dir ${LLVM_SOURCE_DIR})
+  set(llvm_vc_repository ${LLVM_VC_REPOSITORY})
+  set(llvm_vc_revision ${LLVM_VC_REVISION})
+endif()
 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}"
@@ -24,7 +34,11 @@
   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}"
+                           "-DLLVM_VC_REPOSITORY=${llvm_vc_repository}"
+                           "-DLLVM_VC_REVISION=${llvm_vc_revision}"
                            -P "${generate_vcs_version_script}")
 
 # Mark the generated header as being generated.
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
@@ -18,10 +18,7 @@
 # Handle strange terminals
 set(ENV{TERM} "dumb")
 
-function(append_info name path)
-  if(path)
-    get_source_info("${path}" revision repository)
-  endif()
+function(append_info name revision repository)
   if(revision)
     file(APPEND "${HEADER_FILE}.tmp"
       "#define ${name}_REVISION \"${revision}\"\n")
@@ -39,10 +36,15 @@
 endfunction()
 
 foreach(name IN LISTS NAMES)
-  if(NOT DEFINED ${name}_SOURCE_DIR)
+  if(${name}_VC_REPOSITORY AND ${name}_VC_REVISION)
+    set(revision ${${name}_VC_REVISION})
+    set(repository ${${name}_VC_REPOSITORY})
+  elseif(DEFINED ${name}_SOURCE_DIR)
+    get_source_info(${${name}_SOURCE_DIR} revision repository)
+  else()
     message(FATAL_ERROR "${name}_SOURCE_DIR is not defined")
   endif()
-  append_info(${name} "${${name}_SOURCE_DIR}")
+  append_info(${name} ${revision} ${repository})
 endforeach()
 
 # Copy the file only if it has changed.