Backed out changeset f5232023af37 (bug 1021494) because the upstream LLVM bug is now fixed.

Upstream bug: http://llvm.org/bugs/show_bug.cgi?id=20008
Backed out changeset a4a56914be72 (bug 1024836) because the upstream LLVM bug is now fixed.

Upstream bug: http://llvm.org/bugs/show_bug.cgi?id=20008
Backed out changeset 39977f335685 (bug 1024195) because the upstream LLVM bug is now fixed.

Upstream bug: http://llvm.org/bugs/show_bug.cgi?id=20008