diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
index 43440e5f7c..12a93d6a24 100644
--- a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -45,7 +45,17 @@ def initialize(app, consider_all_requests_local = false)
     end
 
     def call(env)
-      @app.call(env)
+      status, headers, body = @app.call(env)
+
+      # Only this middleware cares about RoutingError. So, let's just raise
+      # it here.
+      # TODO: refactor this middleware to handle the X-Cascade scenario without
+      # having to raise an exception.
+      if headers['X-Cascade'] == 'pass'
+        raise ActionController::RoutingError, "No route matches #{env['PATH_INFO'].inspect}"
+      end
+
+      [status, headers, body]
     rescue Exception => exception
       raise exception if env['action_dispatch.show_exceptions'] == false
       render_exception(env, exception)
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index fdbff74071..0d071dd7fe 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -6,10 +6,6 @@
 module ActionDispatch
   module Routing
     class RouteSet #:nodoc:
-      NotFound = lambda { |env|
-        raise ActionController::RoutingError, "No route matches #{env['PATH_INFO'].inspect}"
-      }
-
       PARAMETERS_KEY = 'action_dispatch.request.path_parameters'
 
       class Dispatcher #:nodoc:
@@ -224,7 +220,6 @@ def draw(&block)
       def finalize!
         return if @finalized
         @finalized = true
-        @set.add_route(NotFound)
         @set.freeze
       end
 
diff --git a/actionpack/test/controller/rescue_test.rb b/actionpack/test/controller/rescue_test.rb
index dd991898a8..0f64b77647 100644
--- a/actionpack/test/controller/rescue_test.rb
+++ b/actionpack/test/controller/rescue_test.rb
@@ -326,7 +326,8 @@ def show_errors(exception)
   end
 
   test 'rescue routing exceptions' do
-    @app = ActionDispatch::Rescue.new(SharedTestRoutes) do
+    raiser = proc { |env| raise ActionController::RoutingError, "Did not handle the request" }
+    @app = ActionDispatch::Rescue.new(raiser) do
       rescue_from ActionController::RoutingError, lambda { |env| [200, {"Content-Type" => "text/html"}, ["Gotcha!"]] }
     end
 
@@ -335,7 +336,8 @@ def show_errors(exception)
   end
 
   test 'unrescued exception' do
-    @app = ActionDispatch::Rescue.new(SharedTestRoutes)
+    raiser = proc { |env| raise ActionController::RoutingError, "Did not handle the request" }
+    @app = ActionDispatch::Rescue.new(raiser)
     assert_raise(ActionController::RoutingError) { get '/b00m' }
   end
 
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index b508996467..651a7a6be0 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -392,12 +392,14 @@ def test_admin
       get '/admin', {}, {'REMOTE_ADDR' => '192.168.1.100'}
       assert_equal 'queenbee#index', @response.body
 
-      assert_raise(ActionController::RoutingError) { get '/admin', {}, {'REMOTE_ADDR' => '10.0.0.100'} }
+      get '/admin', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+      assert_equal 'pass', @response.headers['X-Cascade']
 
       get '/admin/accounts', {}, {'REMOTE_ADDR' => '192.168.1.100'}
       assert_equal 'queenbee#accounts', @response.body
 
-      assert_raise(ActionController::RoutingError) { get '/admin/accounts', {}, {'REMOTE_ADDR' => '10.0.0.100'} }
+      get '/admin/accounts', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+      assert_equal 'pass', @response.headers['X-Cascade']
     end
   end
 
@@ -648,10 +650,14 @@ def test_resource_routes_with_only_and_except
       assert_equal 'comments#index', @response.body
       assert_equal '/posts/1/comments', post_comments_path(:post_id => 1)
 
-      assert_raise(ActionController::RoutingError) { post '/posts' }
-      assert_raise(ActionController::RoutingError) { put '/posts/1' }
-      assert_raise(ActionController::RoutingError) { delete '/posts/1' }
-      assert_raise(ActionController::RoutingError) { delete '/posts/1/comments' }
+      post '/posts'
+      assert_equal 'pass', @response.headers['X-Cascade']
+      put '/posts/1'
+      assert_equal 'pass', @response.headers['X-Cascade']
+      delete '/posts/1'
+      assert_equal 'pass', @response.headers['X-Cascade']
+      delete '/posts/1/comments'
+      assert_equal 'pass', @response.headers['X-Cascade']
     end
   end
 
@@ -775,7 +781,8 @@ def test_articles_with_id
       get '/articles/rails/1'
       assert_equal 'articles#with_id', @response.body
 
-      assert_raise(ActionController::RoutingError) { get '/articles/123/1' }
+      get '/articles/123/1'
+      assert_equal 'pass', @response.headers['X-Cascade']
 
       assert_equal '/articles/rails/1', article_with_title_path(:title => 'rails', :id => 1)
     end
@@ -953,19 +960,22 @@ def test_default_params
 
   def test_resource_constraints
     with_test_routes do
-      assert_raise(ActionController::RoutingError) { get '/products/1' }
+      get '/products/1'
+      assert_equal 'pass', @response.headers['X-Cascade']
       get '/products'
       assert_equal 'products#index', @response.body
       get '/products/0001'
       assert_equal 'products#show', @response.body
 
-      assert_raise(ActionController::RoutingError) { get '/products/1/images' }
+      get '/products/1/images'
+      assert_equal 'pass', @response.headers['X-Cascade']
       get '/products/0001/images'
       assert_equal 'images#index', @response.body
       get '/products/0001/images/1'
       assert_equal 'images#show', @response.body
 
-      assert_raise(ActionController::RoutingError) { get '/dashboard', {}, {'REMOTE_ADDR' => '10.0.0.100'} }
+      get '/dashboard', {}, {'REMOTE_ADDR' => '10.0.0.100'}
+      assert_equal 'pass', @response.headers['X-Cascade']
       get '/dashboard', {}, {'REMOTE_ADDR' => '192.168.1.100'}
       assert_equal 'dashboards#show', @response.body
     end