diff --git a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.h b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.h
--- a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.h
+++ b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.h
@@ -24,6 +24,9 @@
 
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  llvm::Optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
 };
 
 } // namespace readability
diff --git a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
--- a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
+++ b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
@@ -33,14 +33,6 @@
       parmVarDecl(hasType(qualType(isConstQualified()))).bind("param");
   Finder->addMatcher(
       functionDecl(unless(isDefinition()),
-                   // Lambdas are always their own definition, but they
-                   // generate a non-definition FunctionDecl too. Ignore those.
-                   // Class template instantiations have a non-definition
-                   // CXXMethodDecl for methods that aren't used in this
-                   // translation unit. Ignore those, as the template will have
-                   // already been checked.
-                   unless(cxxMethodDecl(ofClass(cxxRecordDecl(anyOf(
-                       isLambda(), ast_matchers::isTemplateInstantiation()))))),
                    has(typeLoc(forEach(ConstParamDecl))))
           .bind("func"),
       this);