diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -11408,9 +11408,9 @@
       return false;
   }
 
-  // If we point to before the start of the object, there are no accessible
-  // bytes.
-  if (LVal.getLValueOffset().isNegative()) {
+  // If we point outside of the object, there are no accessible bytes.
+  if (LVal.getLValueOffset().isNegative() ||
+      ((Type & 1) && !LVal.Designator.isValidSubobject())) {
     Size = 0;
     return true;
   }
diff --git a/clang/test/CodeGen/object-size.c b/clang/test/CodeGen/object-size.c
--- a/clang/test/CodeGen/object-size.c
+++ b/clang/test/CodeGen/object-size.c
@@ -310,7 +310,7 @@
 void test25() {
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 false, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN((void*)0x1000, 0);
-  // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 false, i1 true, i1
+  // CHECK: store i32 0
   gi = OBJECT_SIZE_BUILTIN((void*)0x1000, 1);
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 true, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN((void*)0x1000, 2);
@@ -321,7 +321,7 @@
 
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 false, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN((void*)0 + 0x1000, 0);
-  // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 false, i1 true, i1
+  // CHECK: store i32 0
   gi = OBJECT_SIZE_BUILTIN((void*)0 + 0x1000, 1);
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* {{.*}}, i1 true, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN((void*)0 + 0x1000, 2);
@@ -337,7 +337,7 @@
 
   // CHECK: store i32 316
   gi = OBJECT_SIZE_BUILTIN(&t[1].v[11], 0);
-  // CHECK: store i32 312
+  // CHECK: store i32 0
   gi = OBJECT_SIZE_BUILTIN(&t[1].v[12], 1);
   // CHECK: store i32 308
   gi = OBJECT_SIZE_BUILTIN(&t[1].v[13], 2);
@@ -433,7 +433,7 @@
 
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN(d0->snd, 0);
-  // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false, i1 true, i1
+  // CHECK: store i32 0
   gi = OBJECT_SIZE_BUILTIN(d0->snd, 1);
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 true, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN(d0->snd, 2);
@@ -518,7 +518,7 @@
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false, i1 true, i1
   gi = OBJECT_SIZE_BUILTIN(&ds1[9].snd[0], 1);
 
-  // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false, i1 true, i1
+  // CHECK: store i32 0
   gi = OBJECT_SIZE_BUILTIN(&ds0[9].snd[0], 1);
 
   // CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %{{.*}}, i1 false, i1 true, i1