Index: examples/Attribute/Attribute.cpp
===================================================================
--- /dev/null
+++ examples/Attribute/Attribute.cpp
@@ -0,0 +1,61 @@
+//===- Attribute.cpp ------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/AttributeList.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+    Syntax = AttributeList::AS_GNU;
+    AttrKind = AttributeList::AT_Annotate;
+    OptArgs = 1;
+  }
+  virtual bool handleDeclAttribute(Sema &S, Decl *D, const AttributeList &Attr) {
+    /* Check if the decl is at file scope */
+    if (!D->getDeclContext()->isFileContext()) {
+      unsigned ID = S.getDiagnostics().getCustomDiagID(
+        DiagnosticsEngine::Error,
+        "'example' attribute only allowed at file scope");
+      S.Diag(Attr.getLoc(), ID);
+    }
+    /* The attribute can take an optional string argument: check for this */
+    StringRef Str = "";
+    if (Attr.getNumArgs() > 0) {
+      Expr *ArgExpr = Attr.getArgAsExpr(0);
+      StringLiteral *Literal =
+          dyn_cast<StringLiteral>(ArgExpr->IgnoreParenCasts());
+      if (Literal) {
+        Str = Literal->getString();
+      } else {
+        S.Diag(ArgExpr->getLocStart(), diag::err_attribute_argument_type)
+          << Attr.getName() << AANT_ArgumentString;
+      }
+    }
+    /* Attach an annotate attribute to the Decl */
+    D->addAttr(new (S.Context)AnnotateAttr(Attr.getRange(), S.Context,
+                                           "example("+Str.str()+")", 0));
+    return true;
+  }
+};
+
+}
+
+static AttrInfoRegistry::Add<ExampleAttrInfo> X("example", "");
Index: examples/Attribute/CMakeLists.txt
===================================================================
--- /dev/null
+++ examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_loadable_module(Attribute Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+    clangAST
+    clangBasic
+    clangFrontend
+    clangLex
+    LLVMSupport
+    )
+endif()
Index: examples/CMakeLists.txt
===================================================================
--- examples/CMakeLists.txt
+++ examples/CMakeLists.txt
@@ -9,3 +9,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: test/CMakeLists.txt
===================================================================
--- test/CMakeLists.txt
+++ test/CMakeLists.txt
@@ -64,6 +64,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+    Attribute
     AnnotateFunctions
     clang-interpreter
     PrintFunctionNames
Index: test/Frontend/plugin-attribute.c
===================================================================
--- /dev/null
+++ test/Frontend/plugin-attribute.c
@@ -0,0 +1,22 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: [[STR3_VAR:@.+]] = private unnamed_addr constant [21 x i8] c"example(otherstring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@fn1{{.*}}[[STR1_VAR]]{{.*}}@fn2{{.*}}[[STR2_VAR]]{{.*}}@var1{{.*}}[[STR3_VAR]]
+void fn1() __attribute__((example)) { }
+void fn2() __attribute__((example("somestring"))) { }
+int var1 __attribute__((example("otherstring"))) = 1;
+
+#ifdef BAD_ATTRIBUTE
+void fn3() {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scop
+  int var2 __attribute__((example));
+}
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif