Revert r364275, for reapplying the final upstream fix:

Tentatively apply https://reviews.llvm.org/D85659, which fixes an
assertion failure when building world for powerpc. This has been
reported upstream as https://bugs.llvm.org/show_bug.cgi?id=47041.

(cherry picked from commit 30e9d23b5b7e7e64ee77bfe9caa1fc28fd2ae392)