Index: llvm/trunk/lib/Transforms/Coroutines/CoroCleanup.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Coroutines/CoroCleanup.cpp
+++ llvm/trunk/lib/Transforms/Coroutines/CoroCleanup.cpp
@@ -10,6 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "CoroInternal.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Pass.h"
@@ -22,7 +23,8 @@
 namespace {
 // Created on demand if CoroCleanup pass has work to do.
 struct Lowerer : coro::LowererBase {
-  Lowerer(Module &M) : LowererBase(M) {}
+  IRBuilder<> Builder;
+  Lowerer(Module &M) : LowererBase(M), Builder(Context) {}
   bool lowerRemainingCoroIntrinsics(Function &F);
 };
 }
@@ -36,6 +38,23 @@
   FPM.doFinalization();
 }
 
+static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
+  Builder.SetInsertPoint(SubFn);
+  Value *FrameRaw = SubFn->getFrame();
+  int Index = SubFn->getIndex();
+
+  auto *FrameTy = StructType::get(
+      SubFn->getContext(), {Builder.getInt8PtrTy(), Builder.getInt8PtrTy()});
+  PointerType *FramePtrTy = FrameTy->getPointerTo();
+
+  Builder.SetInsertPoint(SubFn);
+  auto *FramePtr = Builder.CreateBitCast(FrameRaw, FramePtrTy);
+  auto *Gep = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index);
+  auto *Load = Builder.CreateLoad(Gep);
+
+  SubFn->replaceAllUsesWith(Load);
+}
+
 bool Lowerer::lowerRemainingCoroIntrinsics(Function &F) {
   bool Changed = false;
 
@@ -57,6 +76,9 @@
       case Intrinsic::coro_id:
         II->replaceAllUsesWith(ConstantTokenNone::get(Context));
         break;
+      case Intrinsic::coro_subfn_addr:
+        lowerSubFn(Builder, cast<CoroSubFnInst>(II));
+        break;
       }
       II->eraseFromParent();
       Changed = true;
@@ -87,7 +109,8 @@
   // in the module.
   bool doInitialization(Module &M) override {
     if (coro::declaresIntrinsics(M, {"llvm.coro.alloc", "llvm.coro.begin",
-                                     "llvm.coro.free", "llvm.coro.id"}))
+                                     "llvm.coro.subfn.addr", "llvm.coro.free",
+                                     "llvm.coro.id"}))
       L = llvm::make_unique<Lowerer>(M);
     return false;
   }
Index: llvm/trunk/lib/Transforms/Coroutines/Coroutines.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Coroutines/Coroutines.cpp
+++ llvm/trunk/lib/Transforms/Coroutines/Coroutines.cpp
@@ -107,7 +107,7 @@
       "llvm.coro.done",    "llvm.coro.end",     "llvm.coro.frame",
       "llvm.coro.free",    "llvm.coro.id",      "llvm.coro.param",
       "llvm.coro.promise", "llvm.coro.resume",  "llvm.coro.save",
-      "llvm.coro.size",    "llvm.coro.suspend",
+      "llvm.coro.size",    "llvm.coro.subfn.addr", "llvm.coro.suspend",
   };
   return Intrinsic::lookupLLVMIntrinsicByName(CoroIntrinsics, Name) != -1;
 }
Index: llvm/trunk/test/Transforms/Coroutines/coro-cleanup.ll
===================================================================
--- llvm/trunk/test/Transforms/Coroutines/coro-cleanup.ll
+++ llvm/trunk/test/Transforms/Coroutines/coro-cleanup.ll
@@ -0,0 +1,18 @@
+; Make sure that all library helper coro intrinsics are lowered.
+; RUN: opt < %s -O0 -enable-coroutines -S | FileCheck %s
+
+; CHECK-LABEL: @uses_library_support_coro_intrinsics(
+; CHECK-NOT:     @llvm.coro
+; CHECK:         ret void
+define void @uses_library_support_coro_intrinsics(i8* %hdl) {
+entry:
+  call void @llvm.coro.resume(i8* %hdl)
+  call void @llvm.coro.destroy(i8* %hdl)
+  call i1 @llvm.coro.done(i8* %hdl)
+  ret void
+}
+
+declare void @llvm.coro.resume(i8*)
+declare void @llvm.coro.destroy(i8*)
+declare i1 @llvm.coro.done(i8*)
+