diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1045,7 +1045,7 @@
   /// ExpressionEvaluationContextRecord object.
   bool isConstantEvaluatedOverride;
 
-  bool isConstantEvaluated() {
+  bool isConstantEvaluated() const {
     return ExprEvalContexts.back().isConstantEvaluated() ||
            isConstantEvaluatedOverride;
   }
@@ -1486,7 +1486,7 @@
   /// Determine if VD, which must be a variable or function, is an external
   /// symbol that nonetheless can't be referenced from outside this translation
   /// unit because its type has no linkage and it's not extern "C".
-  bool isExternalWithNoLinkageType(ValueDecl *VD);
+  bool isExternalWithNoLinkageType(ValueDecl *VD) const;
 
   /// Obtain a sorted list of functions that are undefined but ODR-used.
   void getUndefinedButUsed(
@@ -3548,13 +3548,13 @@
   void ActOnExitFunctionContext();
 
   /// If \p AllowLambda is true, treat lambda as function.
-  DeclContext *getFunctionLevelDeclContext(bool AllowLambda = false);
+  DeclContext *getFunctionLevelDeclContext(bool AllowLambda = false) const;
 
   /// Returns a pointer to the innermost enclosing function, or nullptr if the
   /// current context is not inside a function. If \p AllowLambda is true,
   /// this can return the call operator of an enclosing lambda, otherwise
   /// lambdas are skipped when looking for an enclosing function.
-  FunctionDecl *getCurFunctionDecl(bool AllowLambda = false);
+  FunctionDecl *getCurFunctionDecl(bool AllowLambda = false) const;
 
   /// getCurMethodDecl - If inside of a method body, this returns a pointer to
   /// the method decl for the method being parsed.  If we're currently
@@ -3564,7 +3564,7 @@
   /// getCurFunctionOrMethodDecl - Return the Decl for the current ObjC method
   /// or C function we're in, otherwise return null.  If we're currently
   /// in a 'block', this returns the containing context.
-  NamedDecl *getCurFunctionOrMethodDecl();
+  NamedDecl *getCurFunctionOrMethodDecl() const;
 
   /// Add this decl to the scope shadowed decl chains.
   void PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext = true);
@@ -3577,7 +3577,7 @@
   ///        enclosing namespace set of the context, rather than contained
   ///        directly within it.
   bool isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S = nullptr,
-                     bool AllowInlineNamespace = false);
+                     bool AllowInlineNamespace = false) const;
 
   /// Finds the scope corresponding to the given decl context, if it
   /// happens to be an enclosing scope.  Otherwise return NULL.
@@ -4349,7 +4349,7 @@
     ForExternalRedeclaration
   };
 
-  RedeclarationKind forRedeclarationInCurContext() {
+  RedeclarationKind forRedeclarationInCurContext() const {
     // A declaration with an owning module for linkage can never link against
     // anything that is not visible. We don't need to check linkage here; if
     // the context has internal linkage, redeclaration lookup won't find things
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -793,7 +793,7 @@
 
 /// Determine whether ND is an external-linkage function or variable whose
 /// type has no linkage.
-bool Sema::isExternalWithNoLinkageType(ValueDecl *VD) {
+bool Sema::isExternalWithNoLinkageType(ValueDecl *VD) const {
   // Note: it's not quite enough to check whether VD has UniqueExternalLinkage,
   // because we also want to catch the case where its type has VisibleNoLinkage,
   // which does not affect the linkage of VD.
@@ -1441,7 +1441,7 @@
 // Helper functions.
 //===----------------------------------------------------------------------===//
 
-DeclContext *Sema::getFunctionLevelDeclContext(bool AllowLambda) {
+DeclContext *Sema::getFunctionLevelDeclContext(bool AllowLambda) const {
   DeclContext *DC = CurContext;
 
   while (true) {
@@ -1461,7 +1461,7 @@
 /// getCurFunctionDecl - If inside of a function body, this returns a pointer
 /// to the function decl for the function being parsed.  If we're currently
 /// in a 'block', this returns the containing context.
-FunctionDecl *Sema::getCurFunctionDecl(bool AllowLambda) {
+FunctionDecl *Sema::getCurFunctionDecl(bool AllowLambda) const {
   DeclContext *DC = getFunctionLevelDeclContext(AllowLambda);
   return dyn_cast<FunctionDecl>(DC);
 }
@@ -1473,7 +1473,7 @@
   return dyn_cast<ObjCMethodDecl>(DC);
 }
 
-NamedDecl *Sema::getCurFunctionOrMethodDecl() {
+NamedDecl *Sema::getCurFunctionOrMethodDecl() const {
   DeclContext *DC = getFunctionLevelDeclContext();
   if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
     return cast<NamedDecl>(DC);
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1593,7 +1593,7 @@
 }
 
 bool Sema::isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S,
-                         bool AllowInlineNamespace) {
+                         bool AllowInlineNamespace) const {
   return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
 }