Merge 80596 from mainline.
Mark test as passing on all x86, which it should,
although I don't think anyone cares about this
feature except Darwin.  PR 4825.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_26@84985 91177308-0d34-0410-b5e6-96231b3b80d8