diff --git a/lib/AST/DeclPrinter.cpp b/lib/AST/DeclPrinter.cpp
index 73f5cdb..4f3e8ad 100644
--- a/lib/AST/DeclPrinter.cpp
+++ b/lib/AST/DeclPrinter.cpp
@@ -468,6 +468,10 @@
 
     if (D->hasAttr<NoReturnAttr>())
       Proto += " __attribute((noreturn))";
+
+    if (D->hasAttr<ReturnsTwiceAttr>())
+      Proto += " __attribute((returns_twice))";
+
     if (CXXConstructorDecl *CDecl = dyn_cast<CXXConstructorDecl>(D)) {
       bool HasInitializerList = false;
       for (CXXConstructorDecl::init_const_iterator B = CDecl->init_begin(),
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index f52abef..6ae2d0c 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -729,6 +729,8 @@
 
   // FIXME: handle sseregparm someday...
   if (TargetDecl) {
+    if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
+      FuncAttrs |= llvm::Attribute::ReturnsTwice;
     if (TargetDecl->hasAttr<NoThrowAttr>())
       FuncAttrs |= llvm::Attribute::NoUnwind;
     else if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index d19023d..8e2ff5c 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7263,6 +7263,9 @@
         FD->addAttr(::new (Context) ConstAttr(FD->getLocation(), Context));
     }
 
+    if (Context.BuiltinInfo.isReturnsTwice(BuiltinID) &&
+        !FD->getAttr<ReturnsTwiceAttr>())
+      FD->addAttr(::new (Context) ReturnsTwiceAttr(FD->getLocation(), Context));
     if (Context.BuiltinInfo.isNoThrow(BuiltinID) && !FD->getAttr<NoThrowAttr>())
       FD->addAttr(::new (Context) NoThrowAttr(FD->getLocation(), Context));
     if (Context.BuiltinInfo.isConst(BuiltinID) && !FD->getAttr<ConstAttr>())