Merge commit '7e1a91386e25' from apple/main into swift/next

Author: git apple-llvm automerger

llvm/tools/opt/opt.cpp

@@ -485,7 +485,8 @@ static bool shouldPinPassToLegacyPM(StringRef Pass) {
                                           "expand-reductions",
                                           "indirectbr-expand",
                                           "generic-to-nvvm",
-                                          "expandmemcmp"};
+                                          "expandmemcmp",
+                                          "loop-reduce"};
   for (const auto &P : PassNamePrefix)
     if (Pass.startswith(P))
       return true;