diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -958,7 +958,10 @@
       --NonzeroLength;
   }
 
-  if (NonzeroLength == 0)
+  // Return an all-zero aggregate unless the array is a flexible array member
+  // and Elements isn't empty.
+  if (NonzeroLength == 0 &&
+      (DesiredType->getNumElements() != 0 || Elements.empty()))
     return llvm::ConstantAggregateZero::get(DesiredType);
 
   // Add a zeroinitializer array filler if we have lots of trailing zeroes.
diff --git a/clang/test/CodeGenCXX/flexible-array-init.cpp b/clang/test/CodeGenCXX/flexible-array-init.cpp
--- a/clang/test/CodeGenCXX/flexible-array-init.cpp
+++ b/clang/test/CodeGenCXX/flexible-array-init.cpp
@@ -23,3 +23,14 @@
 struct B { int x; char y; char z[]; };
 B e = {f(), f(), f(), f()}; // expected-error {{cannot compile this flexible array initializer yet}}
 #endif
+
+namespace zero_initializer {
+A a0{0, 0}, a1{0, {0, 0}};
+// CHECK: @_ZN16zero_initializer2a0E = global { i32, [1 x i32] } zeroinitializer,
+// CHECK: @_ZN16zero_initializer2a1E = global { i32, [2 x i32] } zeroinitializer,
+
+struct S { int x[]; };
+
+S s{0};
+// CHECK: @_ZN16zero_initializer1sE = global { [1 x i32] } zeroinitializer,
+}