diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 67aef34a54b9..4105dd89d85c 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2237,10 +2237,8 @@ void FunctionStackPoisoner::poisonStack() {
       IRBuilder<> IRBPoison(ThenTerm);
       if (StackMallocIdx <= 4) {
         int ClassSize = kMinStackMallocSize << StackMallocIdx;
-        if ((int)ShadowBytesAfterReturn.size() != ClassSize) {
-          ShadowBytesAfterReturn.resize(ClassSize,
-                                        kAsanStackUseAfterReturnMagic);
-        }
+        ShadowBytesAfterReturn.resize(ClassSize >> Mapping.Scale,
+                                      kAsanStackUseAfterReturnMagic);
         poisonRedZones(ShadowBytesAfterReturn, IRBPoison, ShadowBase, true);
         Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
             FakeStack,
diff --git a/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll b/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
index a3c852ad04ea..b84a9e74f54d 100644
--- a/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
@@ -44,6 +44,7 @@ entry:
   ; CHECK-UAR: store i64 -723401728380766731
   ; CHECK-UAR: store i64 -723401728380766731
   ; CHECK-UAR: store i64 -723401728380766731
+  ; CHECK-UAR-NOT: store i64
   ; CHECK-UAR: store i8 0
   ; CHECK-UAR-NOT: store
   ; CHECK-UAR: label