diff --git a/actionpack/lib/action_controller/metal/benchmarking.rb b/actionpack/lib/action_controller/metal/benchmarking.rb
index e58df69172..f73f635b0d 100644
--- a/actionpack/lib/action_controller/metal/benchmarking.rb
+++ b/actionpack/lib/action_controller/metal/benchmarking.rb
@@ -53,7 +53,6 @@ module ActionController #:nodoc:
           log_message << " [#{complete_request_uri rescue "unknown"}]"
 
           logger.info(log_message)
-          response.headers["X-Runtime"] = "%.0f" % ms
         else
           super
         end
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index e6f2d30429..d7a89ba2be 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -208,6 +208,7 @@ module Rails
     initializer :initialize_middleware_stack do
       if config.frameworks.include?(:action_controller)
         config.middleware.use(::Rack::Lock, :if => lambda { ActionController::Base.allow_concurrency })
+        config.middleware.use(::Rack::Runtime)
         config.middleware.use(ActionDispatch::ShowExceptions, lambda { ActionController::Base.consider_all_requests_local })
         config.middleware.use(ActionDispatch::Callbacks, lambda { ActionController::Dispatcher.prepare_each_request })
         config.middleware.use(lambda { ActionController::Base.session_store }, lambda { ActionController::Base.session_options })