diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -3473,7 +3473,7 @@
 
 def Uninitialized : InheritableAttr {
   let Spellings = [Clang<"uninitialized", 0>];
-  let Subjects = SubjectList<[LocalVar]>;
+  let Subjects = SubjectList<[Var]>;
   let Documentation = [UninitializedDocs];
 }
 
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -249,7 +249,8 @@
   // variables cannot have an initializer.
   llvm::Constant *Init = nullptr;
   if (Ty.getAddressSpace() == LangAS::opencl_local ||
-      D.hasAttr<CUDASharedAttr>())
+      D.hasAttr<CUDASharedAttr>() ||
+      D.hasAttr<UninitializedAttr>())
     Init = llvm::UndefValue::get(LTy);
   else
     Init = EmitNullConstant(Ty);
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3943,9 +3943,12 @@
   // left undefined.
   bool IsHIPPinnedShadowVar =
       getLangOpts().CUDAIsDevice && D->hasAttr<HIPPinnedShadowAttr>();
+  bool IsUninitializedVar = D->hasAttr<UninitializedAttr>();
   if (getLangOpts().CUDA &&
       (IsCUDASharedVar || IsCUDAShadowVar || IsHIPPinnedShadowVar))
     Init = llvm::UndefValue::get(getTypes().ConvertType(ASTTy));
+  else if (IsUninitializedVar)
+    Init = llvm::UndefValue::get(getTypes().ConvertType(ASTTy));
   else if (!InitExpr) {
     // This is a tentative definition; tentative definitions are
     // implicitly initialized with { 0 }.
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -6501,8 +6501,6 @@
 }
 
 static void handleUninitializedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
-  assert(cast<VarDecl>(D)->getStorageDuration() == SD_Automatic &&
-         "uninitialized is only valid on automatic duration variables");
   D->addAttr(::new (S.Context) UninitializedAttr(S.Context, AL));
 }
 
diff --git a/clang/test/CodeGenCXX/attribute_uninitialized.cpp b/clang/test/CodeGenCXX/attribute_uninitialized.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenCXX/attribute_uninitialized.cpp
@@ -0,0 +1,40 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -std=c++11 -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: @_ZZ4funcvE4data = internal global i32 undef
+int* func(void)
+{
+  static int data [[clang::uninitialized]];
+  return &data;
+}
+
+// No code emitted
+extern int extern_unhelpful_but_harmless [[clang::uninitialized]];
+
+// CHECK: @tentative = global i32 undef
+int tentative  [[clang::uninitialized]];
+
+// CHECK: @_ZL16tentative_static = internal global i32 undef
+static int tentative_static [[clang::uninitialized]] __attribute__((used));
+
+// CHECK: @nominally_zero_init = global i32 undef
+int nominally_zero_init  [[clang::uninitialized]] = 0;
+
+// CHECK: @nominally_value_init = global i32 undef
+int nominally_value_init  [[clang::uninitialized]] = 4;
+
+class trivial
+{
+  float x;
+};
+
+// CHECK: @ut = global %class.trivial undef
+trivial ut [[clang::uninitialized]]; // claims zero init
+
+struct nontrivial
+{
+  nontrivial() : x(3.14) {}
+  double x;
+};
+
+// CHECK: @unt = global %struct.nontrivial undef
+nontrivial unt [[clang::uninitialized]];
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -148,6 +148,7 @@
 // CHECK-NEXT: Target (SubjectMatchRule_function)
 // CHECK-NEXT: TestTypestate (SubjectMatchRule_function_is_member)
 // CHECK-NEXT: TrivialABI (SubjectMatchRule_record)
+// CHECK-NEXT: Uninitialized (SubjectMatchRule_variable)
 // CHECK-NEXT: UseHandle (SubjectMatchRule_variable_is_parameter)
 // CHECK-NEXT: VecReturn (SubjectMatchRule_record)
 // CHECK-NEXT: VecTypeHint (SubjectMatchRule_function)
diff --git a/clang/test/Sema/attr-uninitialized.c b/clang/test/Sema/attr-uninitialized.c
--- a/clang/test/Sema/attr-uninitialized.c
+++ b/clang/test/Sema/attr-uninitialized.c
@@ -6,16 +6,11 @@
 
 void bad() {
   int im_bad __attribute((uninitialized("zero")));  // expected-error {{'uninitialized' attribute takes no arguments}}
-  static int im_baaad __attribute((uninitialized)); // expected-warning {{'uninitialized' attribute only applies to local variables}}
 }
 
-extern int come_on __attribute((uninitialized));                    // expected-warning {{'uninitialized' attribute only applies to local variables}}
-int you_know __attribute((uninitialized));                          // expected-warning {{'uninitialized' attribute only applies to local variables}}
-static int and_the_whole_world_has_to __attribute((uninitialized)); // expected-warning {{'uninitialized' attribute only applies to local variables}}
-
-void answer_right_now() __attribute((uninitialized)) {}                        // expected-warning {{'uninitialized' attribute only applies to local variables}}
-void just_to_tell_you_once_again(__attribute((uninitialized)) int whos_bad) {} // expected-warning {{'uninitialized' attribute only applies to local variables}}
+void answer_right_now() __attribute((uninitialized)) {}                        // expected-warning {{'uninitialized' attribute only applies to variables}}
+void just_to_tell_you_once_again(__attribute((uninitialized)) int whos_bad) {}
 
 struct TheWordIsOut {
-  __attribute((uninitialized)) int youre_doin_wrong; // expected-warning {{'uninitialized' attribute only applies to local variables}}
-} __attribute((uninitialized));                      // expected-warning {{'uninitialized' attribute only applies to local variables}}
+  __attribute((uninitialized)) int youre_doin_wrong; // expected-warning {{'uninitialized' attribute only applies to variables}}
+} __attribute((uninitialized));                      // expected-warning {{'uninitialized' attribute only applies to variables}}