Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -915,6 +915,11 @@
   let Documentation = [LayoutVersionDocs];
 }
 
+def Leaf : IgnoredAttr {
+  let Spellings = [GNU<"leaf">];
+  let Subjects = SubjectList<[Function]>;
+}
+
 def MaxFieldAlignment : InheritableAttr {
   // This attribute has no spellings as it is only ever created implicitly.
   let Spellings = [];
Index: test/Sema/attr-leaf.c
===================================================================
--- /dev/null
+++ test/Sema/attr-leaf.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+// expected-no-diagnostics
+
+void f(void) __attribute__((leaf));