diff --git a/include/clang/AST/ExprCXX.h b/include/clang/AST/ExprCXX.h
index 9631f54..a9699f1 100644
--- a/include/clang/AST/ExprCXX.h
+++ b/include/clang/AST/ExprCXX.h
@@ -324,6 +324,67 @@
   static bool classof(const CXXConstCastExpr *) { return true; }
 };
 
+/// UserDefinedLiteral - A call to a literal operator (C++11 [over.literal])
+/// written as a user-defined literal (C++11 [lit.ext]).
+///
+/// Represents a user-defined literal, e.g. "foo"_bar or 1.23_xyz. While this
+/// is semantically equivalent to a normal call, this AST node provides better
+/// information about the syntactic representation of the literal.
+///
+/// Since literal operators are never found by ADL and can only be declared at
+/// namespace scope, a user-defined literal is never dependent.
+class UserDefinedLiteral : public CallExpr {
+  /// \brief The location of a ud-suffix within the literal.
+  SourceLocation UDSuffixLoc;
+
+public:
+  UserDefinedLiteral(ASTContext &C, Expr *Fn, Expr **Args, unsigned NumArgs,
+                     QualType T, ExprValueKind VK, SourceLocation LitEndLoc,
+                     SourceLocation SuffixLoc)
+    : CallExpr(C, UserDefinedLiteralClass, Fn, 0, Args, NumArgs, T, VK,
+               LitEndLoc), UDSuffixLoc(SuffixLoc) {}
+  explicit UserDefinedLiteral(ASTContext &C, EmptyShell Empty)
+    : CallExpr(C, UserDefinedLiteralClass, Empty) {}
+
+  /// The kind of literal operator which is invoked.
+  enum LiteralOperatorKind {
+    LOK_Raw,      ///< Raw form: operator "" X (const char *)
+    LOK_Template, ///< Raw form: operator "" X<cs...> ()
+    LOK_Integer,  ///< operator "" X (unsigned long long)
+    LOK_Floating, ///< operator "" X (long double)
+    LOK_String,   ///< operator "" X (const CharT *, size_t)
+    LOK_Character ///< operator "" X (CharT)
+  };
+
+  /// getLiteralOperatorKind - Returns the kind of literal operator invocation
+  /// which this expression represents.
+  LiteralOperatorKind getLiteralOperatorKind() const;
+
+  /// getCookedLiteral - If this is not a raw user-defined literal, get the
+  /// underlying cooked literal (representing the literal with the suffix
+  /// removed).
+  Expr *getCookedLiteral();
+  const Expr *getCookedLiteral() const {
+    return const_cast<UserDefinedLiteral*>(this)->getCookedLiteral();
+  }
+
+  /// getUDSuffixLoc - Returns the location of a ud-suffix in the expression.
+  /// For a string literal, there may be multiple identical suffixes. This
+  /// returns the first.
+  SourceLocation getUDSuffixLoc() const { return getRParenLoc(); }
+
+  /// getUDSuffix - Returns the ud-suffix specified for this literal.
+  const IdentifierInfo *getUDSuffix() const;
+
+  static bool classof(const Stmt *S) {
+    return S->getStmtClass() == UserDefinedLiteralClass;
+  }
+  static bool classof(const UserDefinedLiteral *) { return true; }
+
+  friend class ASTStmtReader;
+  friend class ASTStmtWriter;
+};
+
 /// CXXBoolLiteralExpr - [C++ 2.13.5] C++ Boolean Literal.
 ///
 class CXXBoolLiteralExpr : public Expr {
diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index aeb9d05..38a6a85 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -2037,6 +2037,7 @@
 })
 DEF_TRAVERSE_STMT(CXXThisExpr, { })
 DEF_TRAVERSE_STMT(CXXThrowExpr, { })
+DEF_TRAVERSE_STMT(UserDefinedLiteral, { })
 DEF_TRAVERSE_STMT(DesignatedInitExpr, { })
 DEF_TRAVERSE_STMT(ExtVectorElementExpr, { })
 DEF_TRAVERSE_STMT(GNUNullExpr, { })
diff --git a/include/clang/Basic/StmtNodes.td b/include/clang/Basic/StmtNodes.td
index 5018ac1..8d2e8f5 100644
--- a/include/clang/Basic/StmtNodes.td
+++ b/include/clang/Basic/StmtNodes.td
@@ -98,6 +98,7 @@
 def CXXConstCastExpr : DStmt<CXXNamedCastExpr>;
 def CXXFunctionalCastExpr : DStmt<ExplicitCastExpr>;
 def CXXTypeidExpr : DStmt<Expr>;
+def UserDefinedLiteral : DStmt<CallExpr>;
 def CXXBoolLiteralExpr : DStmt<Expr>;
 def CXXNullPtrLiteralExpr : DStmt<Expr>;
 def CXXThisExpr : DStmt<Expr>;
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index bc7ecf5..ae4485c 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -2545,6 +2545,11 @@
                                       const DeclarationNameInfo &NameInfo,
                                       NamedDecl *D);
 
+  ExprResult BuildLiteralOperatorCall(IdentifierInfo *UDSuffix,
+                                      SourceLocation UDSuffixLoc,
+                                      ArrayRef<Expr*> Args,
+                                      SourceLocation LitEndLoc);
+
   ExprResult ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind);
   ExprResult ActOnIntegerConstant(SourceLocation Loc, uint64_t Val);
   ExprResult ActOnNumericConstant(const Token &Tok);
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 0af1d3b..a25851e 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -1136,6 +1136,8 @@
       EXPR_CXX_CONST_CAST,
       /// \brief A CXXFunctionalCastExpr record.
       EXPR_CXX_FUNCTIONAL_CAST,
+      /// \brief A UserDefinedLiteral record.
+      EXPR_USER_DEFINED_LITERAL,
       /// \brief A CXXBoolLiteralExpr record.
       EXPR_CXX_BOOL_LITERAL,
       EXPR_CXX_NULL_PTR_LITERAL,  // CXXNullPtrLiteralExpr
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index e35091a..0fdca5a 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1681,7 +1681,8 @@
     // Fallthrough for generic call handling.
   }
   case CallExprClass:
-  case CXXMemberCallExprClass: {
+  case CXXMemberCallExprClass:
+  case UserDefinedLiteralClass: {
     // If this is a direct call, get the callee.
     const CallExpr *CE = cast<CallExpr>(this);
     if (const Decl *FD = CE->getCalleeDecl()) {
@@ -2014,7 +2015,8 @@
     //     exception-specification
   case CallExprClass:
   case CXXMemberCallExprClass:
-  case CXXOperatorCallExprClass: {
+  case CXXOperatorCallExprClass:
+  case UserDefinedLiteralClass: {
     const CallExpr *CE = cast<CallExpr>(this);
     CanThrowResult CT;
     if (isTypeDependent())
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index dc559f0..039d70c 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -624,6 +624,39 @@
   return new (Buffer) CXXFunctionalCastExpr(EmptyShell(), PathSize);
 }
 
+UserDefinedLiteral::LiteralOperatorKind
+UserDefinedLiteral::getLiteralOperatorKind() const {
+  if (getNumArgs() == 0)
+    return LOK_Template;
+  if (getNumArgs() == 2)
+    return LOK_String;
+
+  assert(getNumArgs() == 1 && "unexpected #args in literal operator call");
+  QualType ParamTy =
+    cast<FunctionDecl>(getCalleeDecl())->getParamDecl(0)->getType();
+  if (ParamTy->isPointerType())
+    return LOK_Raw;
+  if (ParamTy->isAnyCharacterType())
+    return LOK_Character;
+  if (ParamTy->isIntegerType())
+    return LOK_Integer;
+  if (ParamTy->isFloatingType())
+    return LOK_Floating;
+
+  llvm_unreachable("unknown kind of literal operator");
+}
+
+Expr *UserDefinedLiteral::getCookedLiteral() {
+#ifndef NDEBUG
+  LiteralOperatorKind LOK = getLiteralOperatorKind();
+  assert(LOK != LOK_Template && LOK != LOK_Raw && "not a cooked literal");
+#endif
+  return getArg(0);
+}
+
+const IdentifierInfo *UserDefinedLiteral::getUDSuffix() const {
+  return cast<FunctionDecl>(getCalleeDecl())->getLiteralIdentifier();
+}
 
 CXXDefaultArgExpr *
 CXXDefaultArgExpr::Create(ASTContext &C, SourceLocation Loc, 
diff --git a/lib/AST/ExprClassification.cpp b/lib/AST/ExprClassification.cpp
index 693e28c..00160a0 100644
--- a/lib/AST/ExprClassification.cpp
+++ b/lib/AST/ExprClassification.cpp
@@ -269,6 +269,7 @@
   case Expr::CallExprClass:
   case Expr::CXXOperatorCallExprClass:
   case Expr::CXXMemberCallExprClass:
+  case Expr::UserDefinedLiteralClass:
   case Expr::CUDAKernelCallExprClass:
     return ClassifyUnnamed(Ctx, cast<CallExpr>(E)->getCallReturnType());
 
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 08794f3..947f661 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -6243,6 +6243,7 @@
   case Expr::CXXTypeidExprClass:
   case Expr::CXXUuidofExprClass:
   case Expr::CXXNullPtrLiteralExprClass:
+  case Expr::UserDefinedLiteralClass:
   case Expr::CXXThisExprClass:
   case Expr::CXXThrowExprClass:
   case Expr::CXXNewExprClass:
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index ea6e8b2..c4eed7c 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -2439,6 +2439,9 @@
                      Arity);
     break;
 
+  case Expr::UserDefinedLiteralClass:
+    // We follow g++'s approach of mangling a UDL as a call to the literal
+    // operator.
   case Expr::CXXMemberCallExprClass: // fallthrough
   case Expr::CallExprClass: {
     const CallExpr *CE = cast<CallExpr>(E);
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index cd8b6bb..b8e68d8 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -1222,6 +1222,31 @@
   OS << ")";
 }
 
+void StmtPrinter::VisitUserDefinedLiteral(UserDefinedLiteral *Node) {
+  switch (Node->getLiteralOperatorKind()) {
+  case UserDefinedLiteral::LOK_Raw:
+    OS << cast<StringLiteral>(Node->getArg(0))->getString();
+    break;
+  case UserDefinedLiteral::LOK_Template: {
+    DeclRefExpr *DRE = cast<DeclRefExpr>(Node->getCallee());
+    assert(DRE->hasExplicitTemplateArgs());
+    const TemplateArgumentLoc *Args = DRE->getTemplateArgs();
+    for (unsigned i = 0, e = DRE->getNumTemplateArgs(); i != e; ++i) {
+      char C = (char)Args[i].getArgument().getAsIntegral()->getZExtValue();
+      OS << C;
+    }
+    break;
+  }
+  case UserDefinedLiteral::LOK_Integer:
+  case UserDefinedLiteral::LOK_Floating:
+  case UserDefinedLiteral::LOK_String:
+  case UserDefinedLiteral::LOK_Character:
+    PrintExpr(Node->getCookedLiteral());
+    break;
+  }
+  OS << Node->getUDSuffix()->getName();
+}
+
 void StmtPrinter::VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *Node) {
   OS << (Node->getValue() ? "true" : "false");
 }
diff --git a/lib/AST/StmtProfile.cpp b/lib/AST/StmtProfile.cpp
index 7935d6d..db27f82 100644
--- a/lib/AST/StmtProfile.cpp
+++ b/lib/AST/StmtProfile.cpp
@@ -738,6 +738,10 @@
   VisitCXXNamedCastExpr(S);
 }
 
+void StmtProfiler::VisitUserDefinedLiteral(const UserDefinedLiteral *S) {
+  VisitCallExpr(S);
+}
+
 void StmtProfiler::VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *S) {
   VisitExpr(S);
   ID.AddBoolean(S->getValue());
diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index b06cf44..f50cc31 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -935,6 +935,7 @@
     case Stmt::CallExprClass:
     case Stmt::CXXOperatorCallExprClass:
     case Stmt::CXXMemberCallExprClass:
+    case Stmt::UserDefinedLiteralClass:
       return VisitCallExpr(cast<CallExpr>(S), asc);
 
     case Stmt::CaseStmtClass:
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 18aa0fc..9def554 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -656,6 +656,7 @@
   case Expr::CallExprClass:
   case Expr::CXXMemberCallExprClass:
   case Expr::CXXOperatorCallExprClass:
+  case Expr::UserDefinedLiteralClass:
     return EmitCallExprLValue(cast<CallExpr>(E));
   case Expr::VAArgExprClass:
     return EmitVAArgExprLValue(cast<VAArgExpr>(E));
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6b753a1..7d99732 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1172,10 +1172,27 @@
                                        ArrayType::Normal, 0);
 
   // Pass &StringTokLocs[0], StringTokLocs.size() to factory!
-  return Owned(StringLiteral::Create(Context, Literal.GetString(),
-                                     Kind, Literal.Pascal, StrTy,
-                                     &StringTokLocs[0],
-                                     StringTokLocs.size()));
+  StringLiteral *Lit = StringLiteral::Create(Context, Literal.GetString(),
+                                             Kind, Literal.Pascal, StrTy,
+                                             &StringTokLocs[0],
+                                             StringTokLocs.size());
+  if (Literal.getUDSuffix().empty())
+    return Owned(Lit);
+
+  // We're building a user-defined literal.
+  IdentifierInfo *UDSuffix = &Context.Idents.get(Literal.getUDSuffix());
+  SourceLocation UDSuffixLoc = StringTokLocs[0];
+  // FIXME: = Literal.getUDSuffixLoc(getSourceManager());
+
+  // C++11 [lex.ext]p5: The literal L is treated as a call of the form
+  //   operator "" X (str, len)
+  QualType SizeType = Context.getSizeType();
+  llvm::APInt Len(Context.getIntWidth(SizeType), Literal.GetNumStringChars());
+  IntegerLiteral *LenArg = IntegerLiteral::Create(Context, Len, SizeType,
+                                                  StringTokLocs[0]);
+  Expr *Args[] = { Lit, LenArg };
+  return BuildLiteralOperatorCall(UDSuffix, UDSuffixLoc, Args,
+                                  StringTokLocs.back());
 }
 
 ExprResult
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 91e8def..14c773f 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -10895,6 +10895,109 @@
   return MaybeBindToTemporary(TheCall);
 }
 
+static void FilterLookupForLiteralOperator(Sema &S, LookupResult &R,
+                                           ArrayRef<Expr*> Args) {
+  LookupResult::Filter F = R.makeFilter();
+
+  while (F.hasNext()) {
+    FunctionDecl *D = dyn_cast<FunctionDecl>(F.next());
+    // FIXME: using-decls?
+
+    if (!D || D->getNumParams() != Args.size()) {
+      F.erase();
+    } else {
+      // The literal operator's parameter types must exactly match the decayed
+      // argument types.
+      for (unsigned ArgIdx = 0; ArgIdx != Args.size(); ++ArgIdx) {
+        QualType ArgTy = Args[ArgIdx]->getType();
+        QualType ParamTy = D->getParamDecl(ArgIdx)->getType();
+        if (ArgTy->isArrayType())
+          ArgTy = S.Context.getArrayDecayedType(ArgTy);
+        if (!S.Context.hasSameUnqualifiedType(ArgTy, ParamTy)) {
+          F.erase();
+          break;
+        }
+      }
+    }
+  }
+
+  F.done();
+}
+
+/// BuildLiteralOperatorCall - A user-defined literal was found. Look up the
+/// corresponding literal operator, and build a call to it.
+/// FIXME: Support for raw literal operators and literal operator templates.
+ExprResult
+Sema::BuildLiteralOperatorCall(IdentifierInfo *UDSuffix,
+                               SourceLocation UDSuffixLoc,
+                               ArrayRef<Expr*> Args, SourceLocation LitEndLoc) {
+  DeclarationName OpName =
+    Context.DeclarationNames.getCXXLiteralOperatorName(UDSuffix);
+  DeclarationNameInfo OpNameInfo(OpName, UDSuffixLoc);
+  OpNameInfo.setCXXLiteralOperatorNameLoc(UDSuffixLoc);
+
+  LookupResult R(*this, OpName, UDSuffixLoc, LookupOrdinaryName);
+  LookupName(R, /*FIXME*/CurScope);
+  assert(R.getResultKind() != LookupResult::Ambiguous &&
+         "literal operator lookup can't be ambiguous");
+
+  // Filter the lookup results appropriately.
+  FilterLookupForLiteralOperator(*this, R, Args);
+
+  // FIXME: For literal operator templates, we need to perform overload
+  // resolution to deal with SFINAE.
+  FunctionDecl *FD = R.getAsSingle<FunctionDecl>();
+  if (!FD || FD->getNumParams() != Args.size())
+    return ExprError(
+        Diag(UDSuffixLoc, diag::err_ovl_no_viable_oper) << UDSuffix->getName());
+  bool HadMultipleCandidates = false;
+
+  // Check the argument types. This should almost always be a no-op, except
+  // that array-to-pointer decay is applied to string literals.
+  assert(Args.size() <= 2 && "too many arguments for literal operator");
+  Expr *ConvArgs[2];
+  for (unsigned ArgIdx = 0; ArgIdx != Args.size(); ++ArgIdx) {
+    ExprResult InputInit = PerformCopyInitialization(
+      InitializedEntity::InitializeParameter(Context, FD->getParamDecl(ArgIdx)),
+      SourceLocation(), Args[ArgIdx]);
+    if (InputInit.isInvalid())
+      return true;
+    ConvArgs[ArgIdx] = InputInit.take();
+  }
+
+  MarkFunctionReferenced(UDSuffixLoc, FD);
+  DiagnoseUseOfDecl(FD, UDSuffixLoc);
+
+  ExprResult Fn = CreateFunctionRefExpr(*this, FD, HadMultipleCandidates,
+                                        OpNameInfo.getLoc(),
+                                        OpNameInfo.getInfo());
+  if (Fn.isInvalid())
+    return true;
+
+  QualType ResultTy = FD->getResultType();
+  ExprValueKind VK = Expr::getValueKindForType(ResultTy);
+  ResultTy = ResultTy.getNonLValueExprType(Context);
+
+  // FIXME: A literal operator call never uses default arguments.
+  // But is this ambiguous?
+  //   void operator"" _x(const char *p);
+  //   void operator"" _x(const char *p, size_t n = 0);
+  //   123_x
+  // g++ says no, but bizarrely rejects it if the default argument is omitted.
+
+  UserDefinedLiteral *UDL =
+    new (Context) UserDefinedLiteral(Context, Fn.take(), ConvArgs, Args.size(),
+                                     ResultTy, VK, LitEndLoc, UDSuffixLoc);
+
+  if (CheckCallReturnType(FD->getResultType(), UDSuffixLoc, UDL, FD))
+    return ExprError();
+
+  if (CheckFunctionCall(FD, UDL))
+    return ExprError();
+
+  return MaybeBindToTemporary(UDL);
+}
+
 /// FixOverloadedFunctionReference - E is an expression that refers to
 /// a C++ overloaded function (possibly with some parentheses and
 /// perhaps a '&' around it). We have resolved the overloaded function
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 0a0f5c7..8d4d934 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -6088,6 +6088,12 @@
 
 template<typename Derived>
 ExprResult
+TreeTransform<Derived>::TransformUserDefinedLiteral(UserDefinedLiteral *E) {
+  return SemaRef.MaybeBindToTemporary(E);
+}
+
+template<typename Derived>
+ExprResult
 TreeTransform<Derived>::TransformGenericSelectionExpr(GenericSelectionExpr *E) {
   ExprResult ControllingExpr =
     getDerived().TransformExpr(E->getControllingExpr());
diff --git a/lib/Serialization/ASTReaderStmt.cpp b/lib/Serialization/ASTReaderStmt.cpp
index 479805e..a0d7e45 100644
--- a/lib/Serialization/ASTReaderStmt.cpp
+++ b/lib/Serialization/ASTReaderStmt.cpp
@@ -1161,6 +1161,11 @@
   E->setRParenLoc(ReadSourceLocation(Record, Idx));
 }
 
+void ASTStmtReader::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
+  VisitCallExpr(E);
+  E->UDSuffixLoc = ReadSourceLocation(Record, Idx);
+}
+
 void ASTStmtReader::VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) {
   VisitExpr(E);
   E->setValue(Record[Idx++]);
@@ -2029,6 +2034,10 @@
                        /*PathSize*/ Record[ASTStmtReader::NumExprFields]);
       break;
 
+    case EXPR_USER_DEFINED_LITERAL:
+      S = new (Context) UserDefinedLiteral(Context, Empty);
+      break;
+
     case EXPR_CXX_BOOL_LITERAL:
       S = new (Context) CXXBoolLiteralExpr(Empty);
       break;
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 4edfbff..8b6859c 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -720,6 +720,7 @@
   RECORD(EXPR_CXX_REINTERPRET_CAST);
   RECORD(EXPR_CXX_CONST_CAST);
   RECORD(EXPR_CXX_FUNCTIONAL_CAST);
+  RECORD(EXPR_USER_DEFINED_LITERAL);
   RECORD(EXPR_CXX_BOOL_LITERAL);
   RECORD(EXPR_CXX_NULL_PTR_LITERAL);
   RECORD(EXPR_CXX_TYPEID_EXPR);
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index 76bbc85..a59f2b6 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -1144,6 +1144,12 @@
   Code = serialization::EXPR_CXX_FUNCTIONAL_CAST;
 }
 
+void ASTStmtWriter::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
+  VisitCallExpr(E);
+  Writer.AddSourceLocation(E->UDSuffixLoc, Record);
+  Code = serialization::EXPR_USER_DEFINED_LITERAL;
+}
+
 void ASTStmtWriter::VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) {
   VisitExpr(E);
   Record.push_back(E->getValue());
diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 408bcd3..d19cc9c 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -712,7 +712,8 @@
 
     case Stmt::CallExprClass:
     case Stmt::CXXOperatorCallExprClass:
-    case Stmt::CXXMemberCallExprClass: {
+    case Stmt::CXXMemberCallExprClass:
+    case Stmt::UserDefinedLiteralClass: {
       Bldr.takeNodes(Pred);
       VisitCallExpr(cast<CallExpr>(S), Pred, Dst);
       Bldr.addNodes(Dst);
diff --git a/test/CXX/lex/lex.literal/lex.ext/p10.cpp b/test/CXX/lex/lex.literal/lex.ext/p10.cpp
index 7fbd9f8..6652c9a 100644
--- a/test/CXX/lex/lex.literal/lex.ext/p10.cpp
+++ b/test/CXX/lex/lex.literal/lex.ext/p10.cpp
@@ -10,6 +10,6 @@
   // FIXME: Reject these for the right reason.
   123wibble; // expected-error {{suffix 'wibble'}}
   123.0wibble; // expected-error {{suffix 'wibble'}}
-  ""wibble; // expected-warning {{unused}}
-  R"x("hello")x"wibble; // expected-warning {{unused}}
+  ""wibble;
+  R"x("hello")x"wibble;
 }
diff --git a/test/CXX/lex/lex.literal/lex.ext/p8.cpp b/test/CXX/lex/lex.literal/lex.ext/p8.cpp
index 2833769..d907822 100644
--- a/test/CXX/lex/lex.literal/lex.ext/p8.cpp
+++ b/test/CXX/lex/lex.literal/lex.ext/p8.cpp
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -std=c++11 -verify %s
 
-constexpr const char *operator "" _id(const char *p) { return p; }
+using size_t = decltype(sizeof(int));
+constexpr const char *operator "" _id(const char *p, size_t) { return p; }
 constexpr const char *s = "foo"_id "bar" "baz"_id "quux";
 
 constexpr bool streq(const char *p, const char *q) {
@@ -8,12 +9,10 @@
 }
 static_assert(streq(s, "foobarbazquux"), "");
 
-constexpr const char *operator "" _trim(const char *p) {
-  return *p == ' ' ? operator "" _trim(p + 1) : p;
+constexpr const char *operator "" _trim(const char *p, size_t n) {
+  return *p == ' ' ? operator "" _trim(p + 1, n - 1) : p;
 }
 constexpr const char *t = "   " " "_trim "  foo";
-// FIXME: once we implement the semantics of user-defined literals, this should
-// pass.
-static_assert(streq(s, "foo"), ""); // expected-error {{static_assert}}
+static_assert(streq(t, "foo"), "");
 
 const char *u = "foo" "bar"_id "baz" "quux"_di "corge"; // expected-error {{differing user-defined suffixes ('_id' and '_di') in string literal concatenation}}
diff --git a/test/CXX/lex/lex.literal/lex.ext/p9.cpp b/test/CXX/lex/lex.literal/lex.ext/p9.cpp
index e3de34d..65e27b4 100644
--- a/test/CXX/lex/lex.literal/lex.ext/p9.cpp
+++ b/test/CXX/lex/lex.literal/lex.ext/p9.cpp
@@ -6,9 +6,7 @@
 namespace std_example {
 
 int main() {
-  // FIXME: once we implement the semantics of literal operators, this warning
-  // should vanish.
-  L"A" "B" "C"_x; // expected-warning {{expression result unused}}
+  L"A" "B" "C"_x;
   "P"_x "Q" "R"_y; // expected-error {{differing user-defined suffixes ('_x' and '_y') in string literal concatenation}}
 }
 
diff --git a/test/CodeGenCXX/cxx11-user-defined-literal.cpp b/test/CodeGenCXX/cxx11-user-defined-literal.cpp
new file mode 100644
index 0000000..fbd3621
--- /dev/null
+++ b/test/CodeGenCXX/cxx11-user-defined-literal.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+struct S { S(); ~S(); S(const S &); void operator()(int); };
+using size_t = decltype(sizeof(int));
+S operator"" _x(const char *, size_t);
+
+void f() {
+  // CHECK: call void @_Zli2_xPKcm({{.*}}, i8* getelementptr inbounds ([4 x i8]* @{{.*}}, i32 0, i32 0), i64 3)
+  // CHECK: call void @_Zli2_xPKcm({{.*}}, i8* getelementptr inbounds ([4 x i8]* @{{.*}}, i32 0, i32 0), i64 3)
+  // CHECK: call void @_ZN1SD1Ev({{.*}}) nounwind
+  // CHECK: call void @_ZN1SD1Ev({{.*}}) nounwind
+  "foo"_x, "bar"_x;
+}
+
+template<typename T> auto g(T t) -> decltype("foo"_x(t)) { return "foo"_x(t); }
+template<typename T> auto i(T t) -> decltype(operator"" _x("foo", 3)(t)) { return operator"" _x("foo", 3)(t); }
+
+void h() {
+  g(42);
+  i(42);
+}
+
+// CHECK: define {{.*}} @_Z1hv()
+// CHECK:   call void @_Z1gIiEDTclclL_Zli2_xPKcmELA4_S0_ELm3EEfp_EET_(i32 42)
+// CHECK:   call void @_Z1iIiEDTclclL_Zli2_xPKcmELA4_S0_ELi3EEfp_EET_(i32 42)
+
+// CHECK: define {{.*}} @_Z1gIiEDTclclL_Zli2_xPKcmELA4_S0_ELm3EEfp_EET_(i32
+// CHECK:   call void @_Zli2_xPKcm({{.*}}, i8* getelementptr inbounds ([4 x i8]* @{{.*}}, i32 0, i32 0), i64 3)
+// CHECK:   call void @_ZN1SclEi
+// CHECK:   call void @_ZN1SD1Ev
+
+// CHECK: define {{.*}} @_Z1iIiEDTclclL_Zli2_xPKcmELA4_S0_ELi3EEfp_EET_(i32
+// CHECK:   call void @_Zli2_xPKcm({{.*}}, i8* getelementptr inbounds ([4 x i8]* @{{.*}}, i32 0, i32 0), i64 3)
+// CHECK:   call void @_ZN1SclEi
+// CHECK:   call void @_ZN1SD1Ev
diff --git a/test/PCH/cxx11-user-defined-literals.cpp b/test/PCH/cxx11-user-defined-literals.cpp
new file mode 100644
index 0000000..4a7c24b
--- /dev/null
+++ b/test/PCH/cxx11-user-defined-literals.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -pedantic-errors -std=c++11 -emit-pch %s -o %t
+// RUN: %clang_cc1 -pedantic-errors -std=c++11 -include-pch %t -verify %s
+
+#ifndef HEADER_INCLUDED
+
+#define HEADER_INCLUDED
+
+using size_t = decltype(sizeof(int));
+int operator"" _foo(const char *p, size_t);
+
+template<typename T> auto f(T t) -> decltype(t + ""_foo) { return 0; } // expected-note {{substitution failure}}
+
+#else
+
+int j = ""_foo;
+int k = f(0);
+int *l = f(&k);
+struct S {};
+int m = f(S()); // expected-error {{no matching}}
+
+#endif
diff --git a/test/Parser/cxx11-user-defined-literals.cpp b/test/Parser/cxx11-user-defined-literals.cpp
index c2d5af5..e3f79ec 100644
--- a/test/Parser/cxx11-user-defined-literals.cpp
+++ b/test/Parser/cxx11-user-defined-literals.cpp
@@ -44,11 +44,11 @@
 constexpr const char32_t operator"" _id(const char32_t *p, size_t n) { return *p; }
 
 template<int n> struct S {};
-S<"a"_id[0]> sa;
-S<L"b"_id[0]> sb;
-S<u8"c"_id[0]> sc;
-S<u"d"_id[0]> sd;
-S<U"e"_id[0]> se;
+S<"a"_id> sa;
+S<L"b"_id> sb;
+S<u8"c"_id> sc;
+S<u"d"_id> sd;
+S<U"e"_id> se;
 
 S<'w'_id> sw;
 S<L'x'_id> sx;
@@ -58,3 +58,15 @@
 void h() {
   (void)"test"_id "test" L"test";
 }
+
+enum class LitKind { CharStr, WideStr, Char16Str, Char32Str };
+constexpr LitKind operator"" _kind(const char *p, size_t n) { return LitKind::CharStr; }
+constexpr LitKind operator"" _kind(const wchar_t *p, size_t n) { return LitKind::WideStr; }
+constexpr LitKind operator"" _kind(const char16_t *p, size_t n) { return LitKind::Char16Str; }
+constexpr LitKind operator"" _kind(const char32_t *p, size_t n) { return LitKind::Char32Str; }
+
+static_assert("foo"_kind == LitKind::CharStr, "");
+static_assert(u8"foo"_kind == LitKind::CharStr, "");
+static_assert(L"foo"_kind == LitKind::WideStr, "");
+static_assert(u"foo"_kind == LitKind::Char16Str, "");
+static_assert(U"foo"_kind == LitKind::Char32Str, "");
diff --git a/test/SemaCXX/cxx11-ast-print.cpp b/test/SemaCXX/cxx11-ast-print.cpp
new file mode 100644
index 0000000..1f6f947
--- /dev/null
+++ b/test/SemaCXX/cxx11-ast-print.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -std=c++11 -ast-print %s | FileCheck %s
+
+// FIXME: Print the trailing-return-type properly.
+// CHECK: decltype(nullptr) operator "" _foo(const char *p, decltype(sizeof(int)));
+auto operator"" _foo(const char *p, decltype(sizeof(int))) -> decltype(nullptr);
+
+// CHECK: const char *p1 = "bar1"_foo;
+const char *p1 = "bar1"_foo;
+// CHECK: const char *p2 = "bar2"_foo;
+const char *p2 = R"x(bar2)x"_foo;
+// CHECK: const char *p3 = u8"bar3"_foo;
+const char *p3 = u8"bar3"_foo;
diff --git a/tools/libclang/CXCursor.cpp b/tools/libclang/CXCursor.cpp
index 77b6ba2..ac8cf28 100644
--- a/tools/libclang/CXCursor.cpp
+++ b/tools/libclang/CXCursor.cpp
@@ -446,6 +446,7 @@
   case Stmt::CXXConstructExprClass:  
   case Stmt::CXXTemporaryObjectExprClass:
   case Stmt::CXXUnresolvedConstructExprClass:
+  case Stmt::UserDefinedLiteralClass:
     K = CXCursor_CallExpr;
     break;