Revert "This reapplies r207130 with an additional testcase+and a missing check for"

This reverts commit 207235 to investigate msan buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207250 91177308-0d34-0410-b5e6-96231b3b80d8
SCC: Doxygen-ize comments, NFC

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207251 91177308-0d34-0410-b5e6-96231b3b80d8