Index: lib/Transforms/Coroutines/CoroFrame.cpp
===================================================================
--- lib/Transforms/Coroutines/CoroFrame.cpp
+++ lib/Transforms/Coroutines/CoroFrame.cpp
@@ -863,6 +863,15 @@
   splitBlockIfNotFirst(I->getNextNode(), "After" + Name);
 }
 
+// Any values with users not dominated by CoroBegin can't be spilled
+static bool allUsersDominatedByCoroBegin(Value &V, Instruction &CBInst, Function &F) {
+  DominatorTree DT(F);
+  for (User *U : V.users())
+    if (cast<Instruction>(U) && !DT.dominates(&CBInst, cast<Instruction>(U)))
+      return false;
+  return true;
+}
+
 void coro::buildCoroutineFrame(Function &F, Shape &Shape) {
   // Lower coro.dbg.declare to coro.dbg.value, since we are going to rewrite
   // access to local variables.
@@ -915,7 +924,7 @@
   // Collect the spills for arguments and other not-materializable values.
   for (Argument &A : F.args())
     for (User *U : A.users())
-      if (Checker.isDefinitionAcrossSuspend(A, U))
+      if (Checker.isDefinitionAcrossSuspend(A, U) && allUsersDominatedByCoroBegin(A, *Shape.CoroBegin, F))
         Spills.emplace_back(&A, U);
 
   for (Instruction &I : instructions(F)) {
@@ -929,7 +938,7 @@
       continue;
 
     for (User *U : I.users())
-      if (Checker.isDefinitionAcrossSuspend(I, U)) {
+      if (Checker.isDefinitionAcrossSuspend(I, U) && allUsersDominatedByCoroBegin(I, *Shape.CoroBegin, F)) {
         // We cannot spill a token.
         if (I.getType()->isTokenTy())
           report_fatal_error(
Index: test/Transforms/Coroutines/coro-split-mem2reg.ll
===================================================================
--- /dev/null
+++ test/Transforms/Coroutines/coro-split-mem2reg.ll
@@ -0,0 +1,62 @@
+; Tests that coro-split can handle the case when a memory reference
+; which crosses a suspend point is promoted to a register reference
+; by mem2reg.
+; RUN: opt < %s -mem2reg -coro-early -coro-split -coro-elide -S | FileCheck %s
+
+%Allocator = type { void (%Allocator*)* }
+
+declare i8* @customalloc(void (%Allocator*)* nonnull, %Allocator* nonnull, i64)
+
+define i8* @amain(%Allocator*, i16*) {
+Entry:
+  %allocStore = alloca %Allocator*, align 8
+  %id = call token @llvm.coro.id(i32 16, i8* null, i8* null, i8* null)
+  %size = call i64 @llvm.coro.size.i64()
+  store %Allocator* %0, %Allocator** %allocStore, align 8
+  %allocArg = getelementptr inbounds %Allocator, %Allocator* %0, i32 0, i32 0
+  %allocPtr = load void (%Allocator*)*, void (%Allocator*)** %allocArg, align 8
+  %allocSuccess = call fastcc i8* @customalloc(void (%Allocator*)* %allocPtr, %Allocator* %0, i64 %size)
+  %coroBegin = call i8* @llvm.coro.begin(token %id, i8* %allocSuccess)
+  br label %CoroSuspend
+
+CoroSuspend:                                      ; preds = %Entry
+  %suspend = call i8 @llvm.coro.suspend(token none, i1 true)
+  switch i8 %suspend, label %Suspend [
+    i8 0, label %InvalidResume
+    i8 1, label %CheckFree
+  ]
+
+Suspend:                                          ; preds = %CheckFree, %CoroSuspend
+  %end = call i1 @llvm.coro.end(i8* null, i1 false)
+  ret i8* %coroBegin
+
+InvalidResume:                                    ; preds = %CoroSuspend
+  unreachable
+
+CheckFree:                                        ; preds = %CoroSuspend
+  %allocLoad = load %Allocator*, %Allocator** %allocStore, align 8
+  %allocLoadPtr = getelementptr inbounds %Allocator, %Allocator* %allocLoad, i32 0, i32 0
+  %allocLoadVoid = load void (%Allocator*)*, void (%Allocator*)** %allocLoadPtr, align 8
+  %dummy = sub nsw i64 %size, 0
+  call i8* @llvm.coro.free(token %id, i8* %coroBegin)
+  br label %Suspend
+}
+
+; CHECK-LABEL: @amain(
+; CHECK-NOT:   %allocStore =
+; CHECK-NOT:   store %Allocator* %0, %Allocator** %allocStore
+
+; CHECK-LABEL: @amain.destroy(
+; CHECK-NOT:   %allocStore.reload.addr =
+; CHECK:       ret void
+
+; CHECK-LABEL: @amain.cleanup(
+; CHECK-NOT:   %allocStore.reload.addr =
+; CHECK:       ret void
+
+declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*)
+declare i64 @llvm.coro.size.i64()
+declare i8* @llvm.coro.begin(token, i8* writeonly)
+declare i8 @llvm.coro.suspend(token, i1)
+declare i1 @llvm.coro.end(i8*, i1)
+declare i8* @llvm.coro.free(token, i8* nocapture readonly)