Index: clang-tidy/ClangTidyOptions.cpp
===================================================================
--- clang-tidy/ClangTidyOptions.cpp
+++ clang-tidy/ClangTidyOptions.cpp
@@ -241,10 +241,9 @@
       continue;
     }
 
-    ClangTidyOptions Defaults = DefaultOptionsProvider::getOptions(Directory);
-    // Only use checks from the config file.
-    Defaults.Checks = None;
-    return Defaults.mergeWith(*ParsedOptions).mergeWith(OverrideOptions);
+    return DefaultOptionsProvider::getOptions(Directory)
+        .mergeWith(*ParsedOptions)
+        .mergeWith(OverrideOptions);
   }
   return llvm::None;
 }
Index: test/clang-tidy/config-files.cpp
===================================================================
--- test/clang-tidy/config-files.cpp
+++ test/clang-tidy/config-files.cpp
@@ -1,12 +1,12 @@
 // RUN: clang-tidy -dump-config %S/Inputs/config-files/- -- | FileCheck %s -check-prefix=CHECK-BASE
-// CHECK-BASE: Checks: from-parent
+// CHECK-BASE: Checks: {{.*}}from-parent
 // CHECK-BASE: HeaderFilterRegex: parent
 // RUN: clang-tidy -dump-config %S/Inputs/config-files/1/- -- | FileCheck %s -check-prefix=CHECK-CHILD1
-// CHECK-CHILD1: Checks: from-child1
+// CHECK-CHILD1: Checks: {{.*}}from-child1
 // CHECK-CHILD1: HeaderFilterRegex: child1
 // RUN: clang-tidy -dump-config %S/Inputs/config-files/2/- -- | FileCheck %s -check-prefix=CHECK-CHILD2
-// CHECK-CHILD2: Checks: from-parent
+// CHECK-CHILD2: Checks: {{.*}}from-parent
 // CHECK-CHILD2: HeaderFilterRegex: parent
 // RUN: clang-tidy -dump-config -checks='from-command-line' -header-filter='from command line' %S/Inputs/config-files/- -- | FileCheck %s -check-prefix=CHECK-COMMAND-LINE
-// CHECK-COMMAND-LINE: Checks: from-parent,from-command-line
+// CHECK-COMMAND-LINE: Checks: {{.*}}from-parent,from-command-line
 // CHECK-COMMAND-LINE: HeaderFilterRegex: from command line