Index: compiler-rt/trunk/cmake/Modules/CompilerRTDarwinUtils.cmake
===================================================================
--- compiler-rt/trunk/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ compiler-rt/trunk/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -113,7 +113,7 @@
     endif()
   endforeach()
   set(${valid_archs} ${working_archs}
-    CACHE STRING "List of valid architectures for platform ${os}.")
+    CACHE STRING "List of valid architectures for platform ${os}." FORCE)
 endfunction()
 
 # This function checks the host cpusubtype to see if it is post-haswell. Haswell