diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index 5f36ffa926b26..434e1d8dca227 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -439,8 +439,16 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
       dyn_cast<StringLiteral>(Node.getBase()->IgnoreParenImpCasts());
   uint64_t size;
 
-  if (!BaseDRE && !SLiteral)
-    return false;
+  if (!BaseDRE && !SLiteral) {
+    // Try harder to find something that looks like a DeclRefExpr
+    const auto *Member = dyn_cast<MemberExpr>(Node.getBase()->IgnoreParenImpCasts());
+    if (!Member) return false;
+
+    const auto *Value = Finder->getASTContext().getAsConstantArrayType(Member->getMemberDecl()->getType());
+    if (!Value) return false;
+
+    size = Value->getLimitedSize();
+  }
 
   if (BaseDRE) {
     if (!BaseDRE->getDecl())
@@ -455,12 +463,9 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
     size = SLiteral->getLength() + 1;
   }
 
-  if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
-    const APInt ArrIdx = IdxLit->getValue();
-    // FIXME: ArrIdx.isNegative() we could immediately emit an error as that's a
-    // bug
-    if (ArrIdx.isNonNegative() && ArrIdx.getLimitedValue() < size)
-      return true;
+  const auto IntConst = Node.getIdx()->getIntegerConstantExpr(Finder->getASTContext());
+  if (IntConst && 0 <= *IntConst && *IntConst < size) {
+    return true;
   }
 
   return false;
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
index c6c93a27e4b96..0ae5b1b06b5c2 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
@@ -39,6 +39,28 @@ void constant_idx_unsafe(unsigned idx) {
   buffer[10] = 0;       // expected-note{{used in buffer access here}}
 }
 
+enum FooEnum {
+  A = 0,
+  B = 1,
+  C = 2,
+  D
+};
+
+void constant_enum_safe() {
+  int buffer[FooEnum::D] = { 0, 1, 2 }; // expected-warning{{'buffer' is an unsafe buffer that does not perform bounds checks}}
+                                        // expected-note@-1{{change type of 'buffer' to 'std::array' to label it for hardening}}
+  buffer[A] = 0; // no-warning
+  buffer[C] = 0; // no-warning
+  buffer[D] = 0; // expected-note{{used in buffer access here}}
+}
+
+void constant_enum_unsafe(FooEnum e) {
+  int buffer[FooEnum::D] = { 0, 1, 2 }; // expected-warning{{'buffer' is an unsafe buffer that does not perform bounds checks}}
+                                        // expected-note@-1{{change type of 'buffer' to 'std::array' to label it for hardening}}
+
+  buffer[e] = 0; // expected-note{{used in buffer access here}}
+}
+
 void constant_id_string(unsigned idx) {
   char safe_char = "abc"[1]; // no-warning
   safe_char = ""[0];
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
index 0ba605475925b..1636c948da075 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
@@ -96,7 +96,6 @@ void test_attribute_multiple_fields (D d) {
 
    int v = d.buf[0]; //expected-warning{{field 'buf' prone to unsafe buffer manipulation}}
 
-   //expected-warning@+1{{unsafe buffer access}}
    v = d.buf[5]; //expected-warning{{field 'buf' prone to unsafe buffer manipulation}}
 }
 
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
index 642db0e9d3c63..41194a8e3f522 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
@@ -128,25 +128,25 @@ T_t funRetT();
 T_t * funRetTStar();
 
 void testStructMembers(struct T * sp, struct T s, T_t * sp2, T_t s2) {
-  foo(sp->a[1],     // expected-warning{{unsafe buffer access}}
+  foo(sp->a[1],
       sp->b[1],     // expected-warning{{unsafe buffer access}}
-      sp->c.a[1],   // expected-warning{{unsafe buffer access}}
+      sp->c.a[1],
       sp->c.b[1],   // expected-warning{{unsafe buffer access}}
-      s.a[1],       // expected-warning{{unsafe buffer access}}
+      s.a[1],
       s.b[1],       // expected-warning{{unsafe buffer access}}
-      s.c.a[1],     // expected-warning{{unsafe buffer access}}
+      s.c.a[1],
       s.c.b[1],     // expected-warning{{unsafe buffer access}}
-      sp2->a[1],    // expected-warning{{unsafe buffer access}}
+      sp2->a[1],
       sp2->b[1],    // expected-warning{{unsafe buffer access}}
-      sp2->c.a[1],  // expected-warning{{unsafe buffer access}}
+      sp2->c.a[1],
       sp2->c.b[1],  // expected-warning{{unsafe buffer access}}
-      s2.a[1],      // expected-warning{{unsafe buffer access}}
+      s2.a[1],
       s2.b[1],      // expected-warning{{unsafe buffer access}}
-      s2.c.a[1],           // expected-warning{{unsafe buffer access}}
+      s2.c.a[1],
       s2.c.b[1],           // expected-warning{{unsafe buffer access}}
-      funRetT().a[1],      // expected-warning{{unsafe buffer access}}
+      funRetT().a[1],
       funRetT().b[1],      // expected-warning{{unsafe buffer access}}
-      funRetTStar()->a[1], // expected-warning{{unsafe buffer access}}
+      funRetTStar()->a[1],
       funRetTStar()->b[1]  // expected-warning{{unsafe buffer access}}
       );
 }
@@ -213,7 +213,6 @@ void testTypedefs(T_ptr_t p) {
   // expected-warning@-1{{'p' is an unsafe pointer used for buffer access}}
   foo(p[1],       // expected-note{{used in buffer access here}}
       p[1].a[1],  // expected-note{{used in buffer access here}}
-                  // expected-warning@-1{{unsafe buffer access}}
       p[1].b[1]   // expected-note{{used in buffer access here}}
                   // expected-warning@-1{{unsafe buffer access}}
       );