Index: include/clang/AST/Type.h
===================================================================
--- include/clang/AST/Type.h
+++ include/clang/AST/Type.h
@@ -722,27 +722,27 @@
   /// applied to this type.
   unsigned getCVRQualifiers() const;
 
-  bool isConstant(ASTContext& Ctx) const {
+  bool isConstant(const ASTContext& Ctx) const {
     return QualType::isConstant(*this, Ctx);
   }
 
   /// \brief Determine whether this is a Plain Old Data (POD) type (C++ 3.9p10).
-  bool isPODType(ASTContext &Context) const;
+  bool isPODType(const ASTContext &Context) const;
 
   /// Return true if this is a POD type according to the rules of the C++98
   /// standard, regardless of the current compilation's language.
-  bool isCXX98PODType(ASTContext &Context) const;
+  bool isCXX98PODType(const ASTContext &Context) const;
 
   /// Return true if this is a POD type according to the more relaxed rules
   /// of the C++11 standard, regardless of the current compilation's language.
   /// (C++0x [basic.types]p9)
-  bool isCXX11PODType(ASTContext &Context) const;
+  bool isCXX11PODType(const ASTContext &Context) const;
 
   /// Return true if this is a trivial type per (C++0x [basic.types]p9)
-  bool isTrivialType(ASTContext &Context) const;
+  bool isTrivialType(const ASTContext &Context) const;
 
   /// Return true if this is a trivially copyable type (C++0x [basic.types]p9)
-  bool isTriviallyCopyableType(ASTContext &Context) const;
+  bool isTriviallyCopyableType(const ASTContext &Context) const;
 
   // Don't promise in the API that anything besides 'const' can be
   // easily added.
@@ -1084,7 +1084,7 @@
   // These methods are implemented in a separate translation unit;
   // "static"-ize them to avoid creating temporary QualTypes in the
   // caller.
-  static bool isConstant(QualType T, ASTContext& Ctx);
+  static bool isConstant(QualType T, const ASTContext& Ctx);
   static QualType getDesugaredType(QualType T, const ASTContext &Context);
   static SplitQualType getSplitDesugaredType(QualType T);
   static SplitQualType getSplitUnqualifiedTypeImpl(QualType type);
@@ -1619,7 +1619,7 @@
   bool isChar16Type() const;
   bool isChar32Type() const;
   bool isAnyCharacterType() const;
-  bool isIntegralType(ASTContext &Ctx) const;
+  bool isIntegralType(const ASTContext &Ctx) const;
 
   /// Determine whether this type is an integral or enumeration type.
   bool isIntegralOrEnumerationType() const;
@@ -2513,13 +2513,13 @@
 
   /// \brief Determine the number of bits required to address a member of
   // an array with the given element type and number of elements.
-  static unsigned getNumAddressingBits(ASTContext &Context,
+  static unsigned getNumAddressingBits(const ASTContext &Context,
                                        QualType ElementType,
                                        const llvm::APInt &NumElements);
 
   /// \brief Determine the maximum number of active bits that an array's size
   /// can require, which limits the maximum size of the array.
-  static unsigned getMaxSizeBits(ASTContext &Context);
+  static unsigned getMaxSizeBits(const ASTContext &Context);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), getSize(),
@@ -3004,7 +3004,7 @@
 
   /// \brief Determine the type of an expression that calls a function of
   /// this type.
-  QualType getCallResultType(ASTContext &Context) const {
+  QualType getCallResultType(const ASTContext &Context) const {
     return getReturnType().getNonLValueExprType(Context);
   }
 
Index: lib/AST/Type.cpp
===================================================================
--- lib/AST/Type.cpp
+++ lib/AST/Type.cpp
@@ -64,7 +64,7 @@
   return nullptr;
 }
 
-bool QualType::isConstant(QualType T, ASTContext &Ctx) {
+bool QualType::isConstant(QualType T, const ASTContext &Ctx) {
   if (T.isConstQualified())
     return true;
 
@@ -74,7 +74,7 @@
   return T.getAddressSpace() == LangAS::opencl_constant;
 }
 
-unsigned ConstantArrayType::getNumAddressingBits(ASTContext &Context,
+unsigned ConstantArrayType::getNumAddressingBits(const ASTContext &Context,
                                                  QualType ElementType,
                                                const llvm::APInt &NumElements) {
   uint64_t ElementSize = Context.getTypeSizeInChars(ElementType).getQuantity();
@@ -109,7 +109,7 @@
   return TotalSize.getActiveBits();
 }
 
-unsigned ConstantArrayType::getMaxSizeBits(ASTContext &Context) {
+unsigned ConstantArrayType::getMaxSizeBits(const ASTContext &Context) {
   unsigned Bits = Context.getTypeSize(Context.getSizeType());
   
   // Limit the number of bits in size_t so that maximal bit size fits 64 bit
@@ -1616,7 +1616,7 @@
 /// \param Ctx The context in which this type occurs.
 ///
 /// \returns true if the type is considered an integral type, false otherwise.
-bool Type::isIntegralType(ASTContext &Ctx) const {
+bool Type::isIntegralType(const ASTContext &Ctx) const {
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::Int128;
@@ -1958,7 +1958,7 @@
   }
 }
 
-bool QualType::isPODType(ASTContext &Context) const {
+bool QualType::isPODType(const ASTContext &Context) const {
   // C++11 has a more relaxed definition of POD.
   if (Context.getLangOpts().CPlusPlus11)
     return isCXX11PODType(Context);
@@ -1966,7 +1966,7 @@
   return isCXX98PODType(Context);
 }
 
-bool QualType::isCXX98PODType(ASTContext &Context) const {
+bool QualType::isCXX98PODType(const ASTContext &Context) const {
   // The compiler shouldn't query this for incomplete types, but the user might.
   // We return false for that case. Except for incomplete arrays of PODs, which
   // are PODs according to the standard.
@@ -2026,7 +2026,7 @@
   }
 }
 
-bool QualType::isTrivialType(ASTContext &Context) const {
+bool QualType::isTrivialType(const ASTContext &Context) const {
   // The compiler shouldn't query this for incomplete types, but the user might.
   // We return false for that case. Except for incomplete arrays of PODs, which
   // are PODs according to the standard.
@@ -2089,7 +2089,7 @@
   return false;
 }
 
-bool QualType::isTriviallyCopyableType(ASTContext &Context) const {
+bool QualType::isTriviallyCopyableType(const ASTContext &Context) const {
   if ((*this)->isArrayType())
     return Context.getBaseElementType(*this).isTriviallyCopyableType(Context);
 
@@ -2249,7 +2249,7 @@
 // This is effectively the intersection of isTrivialType and
 // isStandardLayoutType. We implement it directly to avoid redundant
 // conversions from a type to a CXXRecordDecl.
-bool QualType::isCXX11PODType(ASTContext &Context) const {
+bool QualType::isCXX11PODType(const ASTContext &Context) const {
   const Type *ty = getTypePtr();
   if (ty->isDependentType())
     return false;