diff --git a/include/clang/Basic/DiagnosticKinds.def b/include/clang/Basic/DiagnosticKinds.def
index beea258..ce41cfd 100644
--- a/include/clang/Basic/DiagnosticKinds.def
+++ b/include/clang/Basic/DiagnosticKinds.def
@@ -751,6 +751,8 @@
      "scalar initializer cannot be empty")
 DIAG(err_illegal_initializer, ERROR,
      "illegal initializer (only variables can be initialized)")
+DIAG(err_implicit_empty_initializer, ERROR,
+     "initializer for aggregate with no elements requires explicit braces")
 
 DIAG(err_redefinition_of_label, ERROR,
      "redefinition of label '%0'")
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 35dda28..6eb072e 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -57,6 +57,13 @@
   else
     assert(0 && "CheckImplicitInitList(): Illegal type");
 
+  if (maxElements == 0) {
+    SemaRef->Diag(ParentIList->getInit(Index)->getLocStart(),
+                  diag::err_implicit_empty_initializer);
+    hadError = true;
+    return;
+  }
+
   // Check the element types *before* we create the implicit init list;
   // otherwise, we might end up taking the wrong number of elements
   unsigned NewIndex = Index;
diff --git a/test/Sema/array-init.c b/test/Sema/array-init.c
index a7f27b6..6925556 100644
--- a/test/Sema/array-init.c
+++ b/test/Sema/array-init.c
@@ -212,3 +212,7 @@
 void varArray() {
   int c[][x] = { 0 }; //expected-error{{variable-sized object may not be initialized}}
 }
+
+// PR2151
+int emptyInit() {struct {} x[] = {6};} //expected-warning{{empty struct extension}} expected-error{{initializer for aggregate with no elements}}
+