diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index 9cf8a47446957..59b735847f18d 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -365,7 +365,7 @@ pub(crate) unsafe fn optimize(
                 .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap());
 
             // FIXME: NewPM doesn't seem to have a facility to provide custom InlineParams.
-            // FIXME: Extra passes.
+            // FIXME: Support extra passes.
             llvm::LLVMRustOptimizeWithNewPassManager(
                 llmod,
                 tm,
diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index 5dbbce635c24e..8cdc8cc860da8 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -628,12 +628,10 @@ LLVMRustOptimizeWithNewPassManager(
   PTO.LoopVectorization = LoopVectorize;
   PTO.SLPVectorization = SLPVectorize;
 
-  // FIXME: What's this?
   PassInstrumentationCallbacks PIC;
   StandardInstrumentations SI;
   SI.registerCallbacks(PIC);
 
-  // FIXME: PGOOpt
   Optional<PGOOptions> PGOOpt;
   if (PGOGenPath) {
     assert(!PGOUsePath);
@@ -736,14 +734,12 @@ LLVMRustOptimizeWithNewPassManager(
       MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
 
       MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
-      // FIXME: PGO?
     } else {
       for (const auto &C : PipelineStartEPCallbacks)
         PB.registerPipelineStartEPCallback(C);
       for (const auto &C : OptimizerLastEPCallbacks)
         PB.registerOptimizerLastEPCallback(C);
 
-      // FIXME: Sanitizers? PGO?
       if (PrepareForThinLTO) {
         MPM = PB.buildThinLTOPreLinkDefaultPipeline(OptLevel, DebugPassManager);
       } else if (PrepareForLTO) {
@@ -759,6 +755,10 @@ LLVMRustOptimizeWithNewPassManager(
     MPM.addPass(NameAnonGlobalPass());
   }
 
+  // Upgrade all calls to old intrinsics first.
+  for (Module::iterator I = TheModule->begin(), E = TheModule->end(); I != E;)
+    UpgradeCallsToIntrinsic(&*I++); // must be post-increment, as we remove
+
   MPM.run(*TheModule, MAM);
 }