diff --git a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
--- a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
@@ -53,6 +53,10 @@
 
 namespace {
 
+AST_MATCHER(QualType, isLocalConstQualified) {
+  return Node.isLocalConstQualified();
+}
+
 struct CheckResult {
   // Source range of the relevant `const` token in the definition being checked.
   CharSourceRange ConstRange;
@@ -95,9 +99,14 @@
 
 void ConstReturnTypeCheck::registerMatchers(MatchFinder *Finder) {
   // Find all function definitions for which the return types are `const`
-  // qualified.
+  // qualified, ignoring decltype types.
+  const auto NonLocalConstDecltypeType = qualType(
+      unless(isLocalConstQualified()), anyOf(decltypeType(), autoType()));
   Finder->addMatcher(
-      functionDecl(returns(isConstQualified()), isDefinition()).bind("func"),
+      functionDecl(
+          returns(allOf(isConstQualified(), unless(NonLocalConstDecltypeType))),
+          isDefinition())
+          .bind("func"),
       this);
 }
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability-const-return-type.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability-const-return-type.cpp
--- a/clang-tools-extra/test/clang-tidy/checkers/readability-const-return-type.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability-const-return-type.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s readability-const-return-type %t
+// RUN: %check_clang_tidy -std=c++14 %s readability-const-return-type %t
 
 //  p# = positive test
 //  n# = negative test
@@ -271,3 +271,25 @@
 
 int **const * n_multiple_ptr();
 int *const & n_pointer_ref();
+
+// Don't warn about const auto types, because it may be impossible to make them non-const
+// without a significant semantics change. Since `auto` drops cv-qualifiers,
+// tests check `decltype(auto)`.
+decltype(auto) n16() {
+  static const int i = 42;
+  return i;
+}
+
+// Don't warn about `decltype(<expr>)` types as well
+const int n17i = 1;
+decltype(n17i) n17() {
+  return 17;
+}
+
+// Do warn when on decltype types with the local const qualifier
+// `const decltype(auto)` won't compile, so check only `const decltype(<expr>)`
+const decltype(n17i) n18() {
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: return type 'const decltype(n17i)
+  // CHECK-FIXES: decltype(n17i) n18() {
+  return 18;
+}