diff --git a/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp b/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
--- a/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp
@@ -56,6 +56,9 @@
 bool Lowerer::lowerRemainingCoroIntrinsics(Function &F) {
   bool Changed = false;
 
+  bool IsPrivateAndUnprocessed =
+      F.hasFnAttribute(CORO_PRESPLIT_ATTR) && F.hasLocalLinkage();
+
   for (Instruction &I : llvm::make_early_inc_range(instructions(F))) {
     if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
       switch (II->getIntrinsicID()) {
@@ -83,6 +86,13 @@
       case Intrinsic::coro_subfn_addr:
         lowerSubFn(Builder, cast<CoroSubFnInst>(II));
         break;
+      case Intrinsic::coro_end:
+      case Intrinsic::coro_suspend_retcon:
+        if (IsPrivateAndUnprocessed) {
+          II->replaceAllUsesWith(UndefValue::get(II->getType()));
+        } else
+          continue;
+        break;
       case Intrinsic::coro_async_size_replace:
         auto *Target = cast<ConstantStruct>(
             cast<GlobalVariable>(II->getArgOperand(0)->stripPointerCasts())
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-once-private.ll b/llvm/test/Transforms/Coroutines/coro-retcon-once-private.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-once-private.ll
@@ -0,0 +1,48 @@
+; RUN: opt < %s -enable-coroutines -passes='default<O0>' -S | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.12.0"
+
+; CHECK: define internal { i8*, i32 } @f(i8* %buffer, i32* %array)
+; CHECK-NEXT: entry:
+; CHECK-NEXT:  unreachable
+
+define internal {i8*, i32} @f(i8* %buffer, i32* %array) {
+entry:
+  %id = call token @llvm.coro.id.retcon.once(i32 8, i32 8, i8* %buffer, i8* bitcast (void (i8*, i1)* @prototype to i8*), i8* bitcast (i8* (i32)* @allocate to i8*), i8* bitcast (void (i8*)* @deallocate to i8*))
+  %hdl = call i8* @llvm.coro.begin(token %id, i8* null)
+  %load = load i32, i32* %array
+  %load.pos = icmp sgt i32 %load, 0
+  br i1 %load.pos, label %pos, label %neg
+
+pos:
+  %unwind0 = call i1 (...) @llvm.coro.suspend.retcon.i1(i32 %load)
+  br i1 %unwind0, label %cleanup, label %pos.cont
+
+pos.cont:
+  store i32 0, i32* %array, align 4
+  br label %cleanup
+
+neg:
+  %unwind1 = call i1 (...) @llvm.coro.suspend.retcon.i1(i32 0)
+  br i1 %unwind1, label %cleanup, label %neg.cont
+
+neg.cont:
+  store i32 10, i32* %array, align 4
+  br label %cleanup
+
+cleanup:
+  call i1 @llvm.coro.end(i8* %hdl, i1 0)
+  unreachable
+}
+
+declare token @llvm.coro.id.retcon.once(i32, i32, i8*, i8*, i8*, i8*)
+declare i8* @llvm.coro.begin(token, i8*)
+declare i1 @llvm.coro.suspend.retcon.i1(...)
+declare i1 @llvm.coro.end(i8*, i1)
+declare i8* @llvm.coro.prepare.retcon(i8*)
+
+declare void @prototype(i8*, i1 zeroext)
+
+declare noalias i8* @allocate(i32 %size)
+declare void @deallocate(i8* %ptr)