Revert "Revert "Another try at making MSVC happy again.""

This didn't work out either.

Discussion at:
  http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140505/105302.html

This reverts commit r208513.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208514 91177308-0d34-0410-b5e6-96231b3b80d8