This is a reland of D126773 / b2a9ea4420127d10b18ae648b16757665f8bbd7c. The removal of `-mllvm -combiner-global-alias-analysis` has landed separately in D128051 / 7b73f53790f3db9ee589dc26a05a481a5e9e6915. And the removal of `-mllvm --tail-merge-threshold=0` is scheduled for removal in a subsequent patch.