Index: cmake/modules/GenerateVersionFromCVS.cmake
===================================================================
--- cmake/modules/GenerateVersionFromCVS.cmake
+++ cmake/modules/GenerateVersionFromCVS.cmake
@@ -8,7 +8,7 @@
 # and SECOND_REPOSITORY and SECOND_REVISION if requested, where "FIRST" and
 # "SECOND" are substituted with the names specified in the input variables.
 
-
+if (LLVM_APPEND_VC_REV)
 
 # Chop off cmake/modules/GetSVN.cmake
 get_filename_component(LLVM_DIR "${CMAKE_SCRIPT_MODE_FILE}" PATH)
@@ -32,6 +32,11 @@
 
 append_info(${NAME} "${SOURCE_DIR}")
 
+else()
+  file(WRITE "${HEADER_FILE}.txt" "")
+endif()
+
+
 # Copy the file only if it has changed.
 execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
   "${HEADER_FILE}.txt" "${HEADER_FILE}")
Index: include/llvm/Support/CMakeLists.txt
===================================================================
--- include/llvm/Support/CMakeLists.txt
+++ include/llvm/Support/CMakeLists.txt
@@ -9,7 +9,6 @@
 endfunction()
 
 macro(find_first_existing_vc_file out_var path)
-  if ( LLVM_APPEND_VC_REV )
     find_program(git_executable NAMES git git.exe git.cmd)
     # Run from a subdirectory to force git to print an absolute path.
     execute_process(COMMAND ${git_executable} rev-parse --git-dir
@@ -30,7 +29,6 @@
         "${path}/.svn/entries" # SVN 1.6
       )
     endif()
-  endif()
 endmacro()
 
 find_first_existing_vc_file(llvm_vc "${LLVM_MAIN_SRC_DIR}")
@@ -40,22 +38,21 @@
 
 set(get_svn_script "${LLVM_CMAKE_PATH}/GenerateVersionFromCVS.cmake")
 
-if(DEFINED llvm_vc)
-  # Create custom target to generate the VC revision include.
-  add_custom_command(OUTPUT "${version_inc}"
-    DEPENDS "${llvm_vc}" "${get_svn_script}"
-    COMMAND
-    ${CMAKE_COMMAND} "-DSOURCE_DIR=${LLVM_MAIN_SRC_DIR}"
-                     "-DNAME=LLVM_REVISION"
-                     "-DHEADER_FILE=${version_inc}"
-                     -P "${get_svn_script}")
-
-  # Mark the generated header as being generated.
-  set_source_files_properties("${version_inc}"
-    PROPERTIES GENERATED TRUE
-               HEADER_FILE_ONLY TRUE)
-else()
-  file(WRITE "${version_inc}" "")
-endif()
+add_custom_command(OUTPUT force_version_inc_check COMMAND ${CMAKE_COMMAND} -E echo_append)
+
+# Create custom target to generate the VC revision include.
+add_custom_command(OUTPUT "${version_inc}"
+  DEPENDS force_version_inc_check "${llvm_vc}" "${get_svn_script}"
+  COMMAND
+  ${CMAKE_COMMAND} "-DSOURCE_DIR=${LLVM_MAIN_SRC_DIR}"
+                   "-DLLVM_APPEND_VC_REV=${LLVM_APPEND_VC_REV}"
+                   "-DNAME=LLVM_REVISION"
+                   "-DHEADER_FILE=${version_inc}"
+                   -P "${get_svn_script}")
+
+# Mark the generated header as being generated.
+set_source_files_properties("${version_inc}"
+  PROPERTIES GENERATED TRUE
+             HEADER_FILE_ONLY TRUE)
 
 add_custom_target(llvm_vcsrevision_h DEPENDS "${version_inc}")