Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -1023,7 +1023,14 @@
                           CodeGenOpts.DebugInfoForProfiling);
   }
 
-  PassBuilder PB(TM.get(), PipelineTuningOptions(), PGOOpt);
+  PipelineTuningOptions PTO;
+  // For historical reasons, loop interleaving is set to mirror setting for loop
+  // unrolling.
+  PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
+  PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
+  PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
+
+  PassBuilder PB(TM.get(), PTO, PGOOpt);
 
   // Attempt to load pass plugins and register their callbacks with PB.
   for (auto &PluginFN : CodeGenOpts.PassPlugins) {