Revert 315440 on behalf of mkazantsev

This patch reverts rL315440 because of the bug described at
https://bugs.llvm.org/show_bug.cgi?id=34937

The fix for the bug is on review as D38944, but not yet ready.  Given this is a regression reverting until a fix is ready is called for.

Max would have done the revert himself, but is having trouble doing a build of fresh LLVM for some reason.  I did the build and test to ensure the revert worked as expected on his behalf.

llvm-svn: 315974