Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -2108,3 +2108,9 @@
   let SemaHandler = 0;
   let Documentation = [Undocumented];
 }
+
+def InternalLinkage : InheritableAttr {
+  let Spellings = [GCC<"internal_linkage">];
+  let Subjects = SubjectList<[Function,Var]>;
+  let Documentation = [InternalLinkageDocs];
+}
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -1612,3 +1612,10 @@
 arguments, with arbitrary offsets.
   }];
 }
+
+def InternalLinkageDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``internal_linkage`` attribute changes the linkage type of the declaration to internal.
+  }];
+}
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -8304,6 +8304,8 @@
   } else if (D->hasAttr<DLLExportAttr>() || D->hasAttr<CUDAGlobalAttr>()) {
     if (L == GVA_DiscardableODR)
       return GVA_StrongODR;
+  } else if (D->hasAttr<InternalLinkageAttr>()) {
+    return GVA_Internal;
   }
   return L;
 }
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -536,7 +536,7 @@
       continue;
     }
 
-    if (!ND->isExternallyVisible()) {
+    if (!ND->isExternallyVisible() || ND->hasAttr<InternalLinkageAttr>()) {
       S.Diag(ND->getLocation(), diag::warn_undefined_internal)
         << isa<VarDecl>(ND) << ND;
     } else {
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -1573,7 +1573,14 @@
 static void handleCommonAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   if (S.LangOpts.CPlusPlus) {
     S.Diag(Attr.getLoc(), diag::err_attribute_not_supported_in_lang)
-      << Attr.getName() << AttributeLangSupport::Cpp;
+        << Attr.getName() << AttributeLangSupport::Cpp;
+    return;
+  }
+
+  if (InternalLinkageAttr *Internal = D->getAttr<InternalLinkageAttr>()) {
+    S.Diag(Attr.getRange().getBegin(), diag::warn_attribute_ignored)
+        << Attr.getName();
+    S.Diag(Internal->getLocation(), diag::note_conflicting_attribute);
     return;
   }
 
@@ -4550,6 +4557,20 @@
                                 Attr.getAttributeSpellingListIndex()));
 }
 
+static void handleInternalLinkageAttr(Sema &S, Decl *D,
+                                      const AttributeList &Attr) {
+  if (CommonAttr *Common = D->getAttr<CommonAttr>()) {
+    S.Diag(Attr.getRange().getBegin(), diag::warn_attribute_ignored)
+        << Attr.getName();
+    S.Diag(Common->getLocation(), diag::note_conflicting_attribute);
+    return;
+  }
+
+  if (!D->hasAttr<InternalLinkageAttr>())
+    D->addAttr(::new (S.Context) InternalLinkageAttr(
+        Attr.getRange(), S.Context, Attr.getAttributeSpellingListIndex()));
+}
+
 /// Handles semantic checking for features that are common to all attributes,
 /// such as checking whether a parameter was properly specified, or the correct
 /// number of arguments were passed, etc.
@@ -4991,6 +5012,9 @@
   case AttributeList::AT_OpenCLImageAccess:
     handleSimpleAttribute<OpenCLImageAccessAttr>(S, D, Attr);
     break;
+  case AttributeList::AT_InternalLinkage:
+    handleInternalLinkageAttr(S, D, Attr);
+    break;
 
   // Microsoft attributes:
   case AttributeList::AT_MSNoVTable:
Index: test/CodeGenCXX/internal_linkage.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/internal_linkage.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+
+__attribute__((internal_linkage)) static void f() {}
+
+class A {
+public:
+  static int y __attribute__((internal_linkage));
+  void f1() __attribute__((internal_linkage));
+  void f2() __attribute__((internal_linkage)) {}
+  void f3();
+  static void f4() __attribute__((internal_linkage)) {}
+  A() __attribute__((internal_linkage)) {}
+  ~A() __attribute__((internal_linkage)) {}
+};
+
+int A::y;
+
+void A::f1() {
+}
+
+void A::f3() __attribute__((internal_linkage)) {
+}
+
+void use() {
+  A a;
+  a.f1();
+  a.f2();
+  a.f3();
+  A::f4();
+  f();
+  int &Y = A::y;
+}
+
+// CHECK-DAG: @_ZN1A1yE = internal global
+// CHECK-DAG: define internal void @_ZL1fv
+// CHECK-DAG: define internal void @_ZN1AC1Ev
+// CHECK-DAG: define internal void @_ZN1AC2Ev
+// CHECK-DAG: define internal void @_ZN1AD1Ev
+// CHECK-DAG: define internal void @_ZN1AD2Ev
+// CHECK-DAG: define internal void @_ZN1A2f1Ev
+// CHECK-DAG: define internal void @_ZN1A2f2Ev
+// CHECK-DAG: define internal void @_ZN1A2f3Ev
+// CHECK-DAG: define internal void @_ZN1A2f4Ev
Index: test/Sema/internal_linkage.c
===================================================================
--- /dev/null
+++ test/Sema/internal_linkage.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int var __attribute__((internal_linkage));
+int var2 __attribute__((internal_linkage,common)); // expected-warning{{'internal_linkage' attribute ignored}} \
+                                                   // expected-note{{conflicting attribute is here}}
+int f() __attribute__((internal_linkage));
+struct __attribute__((internal_linkage)) S { // expected-warning{{'internal_linkage' attribute only applies to variables and functions}}
+};
Index: test/SemaCXX/internal_linkage.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/internal_linkage.cpp
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int f() __attribute__((internal_linkage));
+class __attribute__((internal_linkage)) A { // expected-warning{{'internal_linkage' attribute only applies to variables and functions}}
+public:
+  int x __attribute__((internal_linkage));  // expected-warning{{'internal_linkage' attribute only applies to variables and functions}}
+  static int y __attribute__((internal_linkage));
+  void f1() __attribute__((internal_linkage));
+  void f2() __attribute__((internal_linkage)) {}
+  static void f3() __attribute__((internal_linkage)) {}
+  A() __attribute__((internal_linkage)) {}
+  ~A() __attribute__((internal_linkage)) {}
+};
+
+int A::y;
+
+void A::f1() {
+}