diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 94edcd352af501e001275bd78a348a732dab608e..bfb9b456db0e23ce113ee55de8f39766aab446de 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -124,7 +124,7 @@ module Rails
   #
   # Now you can mount your engine in application's routes just like that:
   #
-  #   MyRailsApp::Application.routes.draw do
+  #   Rails.application.routes.draw do
   #     mount MyEngine::Engine => "/engine"
   #   end
   #
@@ -154,7 +154,7 @@ module Rails
   # Note that now there can be more than one router in your application, and it's better to avoid
   # passing requests through many routers. Consider this situation:
   #
-  #   MyRailsApp::Application.routes.draw do
+  #   Rails.application.routes.draw do
   #     mount MyEngine::Engine => "/blog"
   #     get "/blog/omg" => "main#omg"
   #   end
@@ -164,7 +164,7 @@ module Rails
   # and if there is no such route in +Engine+'s routes, it will be dispatched to <tt>main#omg</tt>.
   # It's much better to swap that:
   #
-  #   MyRailsApp::Application.routes.draw do
+  #   Rails.application.routes.draw do
   #     get "/blog/omg" => "main#omg"
   #     mount MyEngine::Engine => "/blog"
   #   end
@@ -251,7 +251,7 @@ module Rails
   # created to allow you to do that. Consider such a scenario:
   #
   #   # config/routes.rb
-  #   MyApplication::Application.routes.draw do
+  #   Rails.application.routes.draw do
   #     mount MyEngine::Engine => "/my_engine", as: "my_engine"
   #     get "/foo" => "foo#index"
   #   end
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index 28593c5907f9bbe73f0ca38d0213152b86fc3a60..366c72ebaa1a1449a717d71de807ff6ef9e3c788 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -86,7 +86,7 @@ def add_source(source, options={})
       #   end
       def environment(data=nil, options={}, &block)
         sentinel = /class [a-z_:]+ < Rails::Application/i
-        env_file_sentinel = /::Application\.configure do/
+        env_file_sentinel = /Rails\.application\.configure do/
         data = block.call if !data && block_given?
 
         in_root do
diff --git a/railties/lib/rails/generators/rails/app/templates/Rakefile b/railties/lib/rails/generators/rails/app/templates/Rakefile
index 6eb23f68a3050e2be6224c21ab92ca8819943929..ba6b733dd2358d858f00445ebd91c214f0f5d2e5 100644
--- a/railties/lib/rails/generators/rails/app/templates/Rakefile
+++ b/railties/lib/rails/generators/rails/app/templates/Rakefile
@@ -3,4 +3,4 @@
 
 require File.expand_path('../config/application', __FILE__)
 
-<%= app_const %>.load_tasks
+Rails.application.load_tasks
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environment.rb b/railties/lib/rails/generators/rails/app/templates/config/environment.rb
index e080ebd74e195db8bf35f61da24a79d465af78ec..00a613ff04d7514476c6e034f46fa0a3cf62b33a 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environment.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/environment.rb
@@ -2,4 +2,4 @@
 require File.expand_path('../application', __FILE__)
 
 # Initialize the rails application.
-<%= app_const %>.initialize!
+Rails.application.initialize!
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
index 8b64881dbc7478ea9f5c1ac8a0c56ef284967101..91253d15087aa4badb14336cc7b72cfef4f8a70a 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
@@ -1,4 +1,4 @@
-<%= app_const %>.configure do
+Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
   # In the development environment your application's code is reloaded on
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
index c40eef145f818de6d5ca0d1e5e719cc1caec94d2..1dfc9f136b3fb77b6e8fd73d86089815464246b2 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
@@ -1,4 +1,4 @@
-<%= app_const %>.configure do
+Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
   # Code is not reloaded between requests.
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
index 7073d8db330e10aef7ef42ae7061aca7446303df..ba0742f97f92219ca58d82c3a21c3c111849bf32 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
@@ -1,4 +1,4 @@
-<%= app_const %>.configure do
+Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
   # The test environment is used exclusively to run your application's
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt
index efccf72d3d0f8183ef9a61458816b3d8124d19f1..f3cc6098a385f11b35fa77ef66b709c9a860a0b4 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/secret_token.rb.tt
@@ -9,4 +9,4 @@
 
 # Make sure your secret_key_base is kept private
 # if you're sharing your code publicly.
-<%= app_const %>.config.secret_key_base = '<%= app_secret %>'
+Rails.application.config.secret_key_base = '<%= app_secret %>'
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/session_store.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/session_store.rb.tt
index 4a099a4ce281c3c2e846a3aa46c42e86ed932abb..2bb9b82c617dc3c1abd9c6fc6751955235c52664 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/session_store.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/session_store.rb.tt
@@ -1,3 +1,3 @@
 # Be sure to restart your server when you modify this file.
 
-<%= app_const %>.config.session_store :cookie_store, key: <%= "'_#{app_name}_session'" %>
+Rails.application.config.session_store :cookie_store, key: <%= "'_#{app_name}_session'" %>
diff --git a/railties/lib/rails/generators/rails/app/templates/config/routes.rb b/railties/lib/rails/generators/rails/app/templates/config/routes.rb
index f877fa1f8a7006573a2a21e14e62271a36bb3a26..89399bcc9f6ed85578f6f25d32a954886eafe4db 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/routes.rb
+++ b/railties/lib/rails/generators/rails/app/templates/config/routes.rb
@@ -1,4 +1,4 @@
-<%= app_const %>.routes.draw do
+Rails.application.routes.draw do
   # The priority is based upon order of creation: first created -> highest priority.
   # See how all your routes lay out with "rake routes".
 
diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index 2b6ad1ff2dbfdf99376d53e4c6153a65fc041ece..89ca8cbe11830ce8cdad5a20d9bd0709312789aa 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -179,7 +179,7 @@ def respond_to_missing?(*args)
       # Railtie::Configurable, but this module is no longer required for all
       # subclasses of Railtie so we provide the class method here.
       def configure(&block)
-        class_eval(&block)
+        instance.configure(&block)
       end
 
       protected
@@ -206,6 +206,10 @@ def initialize
       end
     end
 
+    def configure(&block)
+      instance_eval(&block)
+    end
+
     def config
       @config ||= Railtie::Configuration.new
     end
diff --git a/railties/test/generators/actions_test.rb b/railties/test/generators/actions_test.rb
index f8fa8ee15376308b5b3a5bae494762fb9729b5c1..0db40c1d32d70706029ac0fdd7906c2e76924d88 100644
--- a/railties/test/generators/actions_test.rb
+++ b/railties/test/generators/actions_test.rb
@@ -103,7 +103,7 @@ def test_environment_should_include_data_in_environment_initializer_block_with_e
     run_generator
     autoload_paths = 'config.autoload_paths += %w["#{Rails.root}/app/extras"]'
     action :environment, autoload_paths, env: 'development'
-    assert_file "config/environments/development.rb", /Application\.configure do\n  #{Regexp.escape(autoload_paths)}/
+    assert_file "config/environments/development.rb", /Rails\.application\.configure do\n  #{Regexp.escape(autoload_paths)}/
   end
 
   def test_environment_with_block_should_include_block_contents_in_environment_initializer_block
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index 5fdf58c8eed2ea1b62917bb0bacc6bee688ee3cf..f70c90bffa915c1767ad48790288abc6033f91ff 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -65,7 +65,7 @@ def test_invalid_application_name_raises_an_error
 
   def test_invalid_application_name_is_fixed
     run_generator [File.join(destination_root, "things-43")]
-    assert_file "things-43/config/environment.rb", /Things43::Application\.initialize!/
+    assert_file "things-43/config/environment.rb", /Rails\.application\.initialize!/
     assert_file "things-43/config/application.rb", /^module Things43$/
   end
 
@@ -111,7 +111,7 @@ def test_application_name_is_detected_if_it_exists_and_app_folder_renamed
                                                                destination_root: app_moved_root, shell: @shell
     generator.send(:app_const)
     quietly { generator.send(:create_config_files) }
-    assert_file "myapp_moved/config/environment.rb", /Myapp::Application\.initialize!/
+    assert_file "myapp_moved/config/environment.rb", /Rails\.application\.initialize!/
     assert_file "myapp_moved/config/initializers/session_store.rb", /_myapp_session/
   end
 
@@ -131,7 +131,7 @@ def test_rails_update_generates_correct_session_key
 
   def test_application_names_are_not_singularized
     run_generator [File.join(destination_root, "hats")]
-    assert_file "hats/config/environment.rb", /Hats::Application\.initialize!/
+    assert_file "hats/config/environment.rb", /Rails\.application\.initialize!/
   end
 
   def test_gemfile_has_no_whitespace_errors