Index: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1924,11 +1924,13 @@
           return true;
         if (auto *MemSetI = dyn_cast<MemSetInst>(UpperInst)) {
           if (auto *SI = dyn_cast<StoreInst>(DefInst)) {
-            // MemSetInst must have a write location.
-            MemoryLocation UpperLoc = *getLocForWrite(UpperInst);
+            Optional<MemoryLocation> UpperLoc = getLocForWrite(UpperInst);
+            if (!UpperLoc)
+              return false;
+
             int64_t InstWriteOffset = 0;
             int64_t DepWriteOffset = 0;
-            auto OR = isOverwrite(UpperInst, DefInst, UpperLoc, *MaybeDefLoc,
+            auto OR = isOverwrite(UpperInst, DefInst, *UpperLoc, *MaybeDefLoc,
                                   InstWriteOffset, DepWriteOffset);
             Value *StoredByte = isBytewiseValue(SI->getValueOperand(), DL);
             return StoredByte && StoredByte == MemSetI->getOperand(1) &&
Index: llvm/test/Transforms/DeadStoreElimination/memset-presplitcoroutine.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/DeadStoreElimination/memset-presplitcoroutine.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -dse -S %s | FileCheck %s
+
+declare i8* @_Znwm() local_unnamed_addr #0
+
+; Function Attrs: argmemonly nounwind willreturn writeonly
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #1
+
+define i8* @test2(i1 %c, i64 %N) presplitcoroutine {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[COND_TRUE_I_I_I:%.*]], label [[COND_END_I_I_I:%.*]]
+; CHECK:       cond.true.i.i.i:
+; CHECK-NEXT:    ret i8* null
+; CHECK:       cond.end.i.i.i:
+; CHECK-NEXT:    [[ALLOC:%.*]] = tail call noalias nonnull i8* @_Znam() #[[ATTR3:[0-9]+]]
+; CHECK-NEXT:    [[ALLOC_BC:%.*]] = bitcast i8* [[ALLOC]] to i64*
+; CHECK-NEXT:    tail call void @llvm.memset.p0i8.i64(i8* nonnull align 8 [[ALLOC]], i8 0, i64 [[N:%.*]], i1 false) #[[ATTR4:[0-9]+]]
+; CHECK-NEXT:    store i64 0, i64* [[ALLOC_BC]], align 8
+; CHECK-NEXT:    ret i8* [[ALLOC]]
+;
+entry:
+  br i1 %c, label %cond.true.i.i.i, label %cond.end.i.i.i
+
+cond.true.i.i.i:                                  ; preds = %entry
+  ret i8* null
+
+cond.end.i.i.i:                                   ; preds = %entry
+  %alloc = tail call noalias nonnull i8* @_Znam() #2
+  %alloc.bc = bitcast i8* %alloc to i64*
+  tail call void @llvm.memset.p0i8.i64(i8* nonnull align 8 %alloc, i8 0, i64 %N, i1 false) #1
+  store i64 0, i64* %alloc.bc, align 8
+  ret i8* %alloc
+}
+
+declare i8* @_Znam()
+
+attributes #0 = { "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn writeonly }
+attributes #2 = { builtin nounwind }