diff --git a/actionmailer/lib/action_mailer.rb b/actionmailer/lib/action_mailer.rb
index 32e6183ff618b..cfbe2f1cbd2b7 100644
--- a/actionmailer/lib/action_mailer.rb
+++ b/actionmailer/lib/action_mailer.rb
@@ -35,7 +35,10 @@
 module ActionMailer
   extend ::ActiveSupport::Autoload
 
-  autoload :Collector
+  eager_autoload do
+    autoload :Collector
+  end
+
   autoload :Base
   autoload :DeliveryMethods
   autoload :MailHelper
diff --git a/actionmailer/lib/action_mailer/railtie.rb b/actionmailer/lib/action_mailer/railtie.rb
index 5c03a29f0fc5b..8679096735044 100644
--- a/actionmailer/lib/action_mailer/railtie.rb
+++ b/actionmailer/lib/action_mailer/railtie.rb
@@ -5,6 +5,7 @@
 module ActionMailer
   class Railtie < Rails::Railtie
     config.action_mailer = ActiveSupport::OrderedOptions.new
+    config.eager_load_namespaces << ActionMailer
 
     initializer "action_mailer.logger" do
       ActiveSupport.on_load(:action_mailer) { self.logger ||= Rails.logger }
diff --git a/actionpack/lib/action_controller.rb b/actionpack/lib/action_controller.rb
index ceb90f8ceec05..31df9d605c962 100644
--- a/actionpack/lib/action_controller.rb
+++ b/actionpack/lib/action_controller.rb
@@ -48,6 +48,12 @@ module ActionController
   eager_autoload do
     autoload :RecordIdentifier
   end
+
+  def self.eager_load!
+    super
+    ActionController::Caching.eager_load!
+    HTML.eager_load!
+  end
 end
 
 # All of these simply register additional autoloads
diff --git a/actionpack/lib/action_controller/railtie.rb b/actionpack/lib/action_controller/railtie.rb
index 851a2c4aeec20..3ecc105e22ee0 100644
--- a/actionpack/lib/action_controller/railtie.rb
+++ b/actionpack/lib/action_controller/railtie.rb
@@ -9,6 +9,8 @@ module ActionController
   class Railtie < Rails::Railtie #:nodoc:
     config.action_controller = ActiveSupport::OrderedOptions.new
 
+    config.eager_load_namespaces << ActionController
+
     initializer "action_controller.assets_config", :group => :all do |app|
       app.config.action_controller.assets_dir ||= app.config.paths["public"].first
     end
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index b3829970524a5..57b4678addaeb 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -38,9 +38,11 @@ module ActionDispatch
   class IllegalStateError < StandardError
   end
 
-  autoload_under 'http' do
-    autoload :Request
-    autoload :Response
+  eager_autoload do
+    autoload_under 'http' do
+      autoload :Request
+      autoload :Response
+    end
   end
 
   autoload_under 'middleware' do
diff --git a/actionpack/lib/action_dispatch/railtie.rb b/actionpack/lib/action_dispatch/railtie.rb
index 5aad8dd23ad59..ccc0435a39f23 100644
--- a/actionpack/lib/action_dispatch/railtie.rb
+++ b/actionpack/lib/action_dispatch/railtie.rb
@@ -25,6 +25,8 @@ class Railtie < Rails::Railtie
       'X-Content-Type-Options' => 'nosniff'
     }
 
+    config.eager_load_namespaces << ActionDispatch
+
     initializer "action_dispatch.configure" do |app|
       ActionDispatch::Http::URL.tld_length = app.config.action_dispatch.tld_length
       ActionDispatch::Request.ignore_accept_header = app.config.action_dispatch.ignore_accept_header
diff --git a/actionpack/lib/action_view.rb b/actionpack/lib/action_view.rb
index 4bd72c5520f70..9d11c284f592a 100644
--- a/actionpack/lib/action_view.rb
+++ b/actionpack/lib/action_view.rb
@@ -38,7 +38,6 @@ module ActionView
     autoload :PathSet
     autoload :Template
 
-
     autoload_under "renderer" do
       autoload :Renderer
       autoload :AbstractRenderer
@@ -77,6 +76,11 @@ module ActionView
   autoload :TestCase
 
   ENCODING_FLAG = '#.*coding[:=]\s*(\S+)[ \t]*'
+
+  def self.eager_load!
+    super
+    ActionView::Template.eager_load!
+  end
 end
 
 require 'active_support/core_ext/string/output_safety'
diff --git a/actionpack/lib/action_view/railtie.rb b/actionpack/lib/action_view/railtie.rb
index 9f5e3be45449b..2d36deaa781c1 100644
--- a/actionpack/lib/action_view/railtie.rb
+++ b/actionpack/lib/action_view/railtie.rb
@@ -9,6 +9,8 @@ class Railtie < Rails::Railtie
     config.action_view.javascript_expansions = { :defaults => %w(jquery jquery_ujs) }
     config.action_view.embed_authenticity_token_in_remote_forms = false
 
+    config.eager_load_namespaces << ActionView
+
     initializer "action_view.embed_authenticity_token_in_remote_forms" do |app|
       ActiveSupport.on_load(:action_view) do
         ActionView::Helpers::FormTagHelper.embed_authenticity_token_in_remote_forms =
diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index ec2d734647ac0..d1cc19ec6b8ba 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -34,7 +34,6 @@ module ActiveModel
   autoload :Conversion
   autoload :Dirty
   autoload :EachValidator, 'active_model/validator'
-  autoload :Errors
   autoload :Lint
   autoload :MassAssignmentSecurity
   autoload :Model
@@ -49,11 +48,22 @@ module ActiveModel
   autoload :Validations
   autoload :Validator
 
+  eager_autoload do
+    autoload :Errors
+  end
+
   module Serializers
     extend ActiveSupport::Autoload
 
-    autoload :JSON
-    autoload :Xml
+    eager_autoload do
+      autoload :JSON
+      autoload :Xml
+    end
+  end
+
+  def eager_load!
+    super
+    ActiveModel::Serializer.eager_load!
   end
 end
 
diff --git a/activemodel/lib/active_model/railtie.rb b/activemodel/lib/active_model/railtie.rb
index 63ffe5db637e3..f239758b35cce 100644
--- a/activemodel/lib/active_model/railtie.rb
+++ b/activemodel/lib/active_model/railtie.rb
@@ -1,2 +1,8 @@
 require "active_model"
-require "rails"
\ No newline at end of file
+require "rails"
+
+module ActiveModel
+  class Railtie < Rails::Railtie
+    config.eager_load_namespaces << ActiveModel
+  end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 39427bc2960de..fa94f6a94130a 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -160,6 +160,15 @@ module Tasks
 
   autoload :TestCase
   autoload :TestFixtures, 'active_record/fixtures'
+
+  def self.eager_load!
+    super
+    ActiveRecord::Locking.eager_load!
+    ActiveRecord::Scoping.eager_load!
+    ActiveRecord::Associations.eager_load!
+    ActiveRecord::AttributeMethods.eager_load!
+    ActiveRecord::ConnectionAdapters.eager_load!
+  end
 end
 
 ActiveSupport.on_load(:active_record) do
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 672d9a4246f4d..ecf8547e6723b 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -29,8 +29,11 @@ class Railtie < Rails::Railtie
       'ActiveRecord::RecordNotSaved'   => :unprocessable_entity
     )
 
+
     config.active_record.use_schema_cache_dump = true
 
+    config.eager_load_namespaces << ActiveRecord
+
     rake_tasks do
       require "active_record/base"
       load "active_record/railties/databases.rake"
diff --git a/activesupport/lib/active_support/railtie.rb b/activesupport/lib/active_support/railtie.rb
index 30ac8810905e9..aa8d408da913a 100644
--- a/activesupport/lib/active_support/railtie.rb
+++ b/activesupport/lib/active_support/railtie.rb
@@ -5,6 +5,8 @@ module ActiveSupport
   class Railtie < Rails::Railtie
     config.active_support = ActiveSupport::OrderedOptions.new
 
+    config.eager_load_namespaces << ActiveSupport
+
     initializer "active_support.deprecation_behavior" do |app|
       if deprecation = app.config.active_support.deprecation
         ActiveSupport::Deprecation.behavior = deprecation
diff --git a/guides/source/configuring.textile b/guides/source/configuring.textile
index 72ae033760365..2c90143394c68 100644
--- a/guides/source/configuring.textile
+++ b/guides/source/configuring.textile
@@ -107,8 +107,6 @@ end
 
 * +config.middleware+ allows you to configure the application's middleware. This is covered in depth in the "Configuring Middleware":#configuring-middleware section below.
 
-* +config.preload_frameworks+ enables or disables preloading all frameworks at startup. Enabled by +config.threadsafe!+. Defaults to +nil+, so is disabled.
-
 * +config.queue+ configures a different queue implementation for the application. Defaults to +Rails::Queueing::Queue+. Note that, if the default queue is changed, the default +queue_consumer+ is not going to be initialized, it is up to the new queue implementation to handle starting and shutting down its own consumer(s).
 
 * +config.queue_consumer+ configures a different consumer implementation for the default queue. Defaults to +Rails::Queueing::ThreadedConsumer+.
@@ -127,7 +125,7 @@ config.session_store :my_custom_store
 
 This custom store must be defined as +ActionDispatch::Session::MyCustomStore+. In addition to symbols, they can also be objects implementing a certain API, like +ActiveRecord::SessionStore+, in which case no special namespace is required.
 
-* +config.threadsafe!+ enables +cache_classes+, +dependency_loading+, +eager_load+ and +preload_frameworks+ to make the application threadsafe.
+* +config.threadsafe!+ enables +cache_classes+ and +eager_load+ to make the application threadsafe.
 
 WARNING: Threadsafe operation is incompatible with the normal workings of development mode Rails. In particular, automatic dependency loading and class reloading are automatically disabled when you call +config.threadsafe!+.
 
@@ -654,8 +652,6 @@ Serves as a placeholder so that +:load_environment_config+ can be defined to run
 
 *+load_active_support+* Requires +active_support/dependencies+ which sets up the basis for Active Support. Optionally requires +active_support/all+ if +config.active_support.bare+ is un-truthful, which is the default.
 
-*+preload_frameworks+* Loads all autoload dependencies of Rails automatically if +config.preload_frameworks+ is +true+ or "truthful". By default this configuration option is disabled. In Rails, when internal classes are referenced for the first time they are autoloaded. +:preload_frameworks+ loads all of this at once on initialization.
-
 *+initialize_logger+* Initializes the logger (an +ActiveSupport::BufferedLogger+ object) for the application and makes it accessible at +Rails.logger+, provided that no initializer inserted before this point has defined +Rails.logger+.
 
 *+initialize_cache+* If +Rails.cache+ isn't set yet, initializes the cache by referencing the value in +config.cache_store+ and stores the outcome as +Rails.cache+. If this object responds to the +middleware+ method, its middleware is inserted before +Rack::Runtime+ in the middleware stack.
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 32039c26f37cc..ae872f2bb0961 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -83,13 +83,6 @@ def initialize
       @queue            = nil
     end
 
-    # Eager load all dependencies before eager loading
-    # the application.
-    def eager_load!
-      railties.each(&:eager_load!)
-      super
-    end
-
     # Returns true if the application is initialized.
     def initialized?
       @initialized
diff --git a/railties/lib/rails/application/bootstrap.rb b/railties/lib/rails/application/bootstrap.rb
index 1e5f95336ffd9..a1bc95550b14a 100644
--- a/railties/lib/rails/application/bootstrap.rb
+++ b/railties/lib/rails/application/bootstrap.rb
@@ -16,7 +16,7 @@ module Bootstrap
       initializer :set_eager_load, :group => :all do
         if config.eager_load.nil?
           warn <<-INFO
-config.eager_load is set to nil. Please update your config/environments file accordingly:
+config.eager_load is set to nil. Please update your config/environments/*.rb files accordingly:
 
   * development - set it to false
   * test - set it to false (unless you use a tool that preloads your test environment)
@@ -27,13 +27,6 @@ module Bootstrap
         end
       end
 
-      # Preload all frameworks specified by the Configuration#frameworks.
-      # Used by Passenger to ensure everything's loaded before forking and
-      # to avoid autoload race conditions in JRuby.
-      initializer :preload_frameworks, :group => :all do
-        ActiveSupport::Autoload.eager_autoload! if config.preload_frameworks
-      end
-
       # Initialize the logger early in the stack in case we need to log some deprecation.
       initializer :initialize_logger, :group => :all do
         Rails.logger ||= config.logger || begin
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 77d89f0cb9624..5c7cf412acad7 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -9,7 +9,7 @@ class Configuration < ::Rails::Engine::Configuration
                     :cache_classes, :cache_store, :consider_all_requests_local, :console,
                     :eager_load, :exceptions_app, :file_watcher, :filter_parameters,
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags,
-                    :preload_frameworks, :railties_order, :relative_url_root, :secret_token,
+                    :railties_order, :relative_url_root, :secret_token,
                     :serve_static_assets, :ssl_options, :static_cache_control, :session_options,
                     :time_zone, :reload_classes_only_on_change,
                     :queue, :queue_consumer
@@ -95,7 +95,6 @@ def paths
       # after boot, and disables reloading code on every request, as these are
       # fundamentally incompatible with thread safety.
       def threadsafe!
-        @preload_frameworks = true
         @cache_classes = true
         @eager_load = true
         self
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index ba9f501546250..1952a0fc3aa76 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -52,7 +52,7 @@ module Finisher
       initializer :eager_load! do
         if config.eager_load
           ActiveSupport.run_load_hooks(:before_eager_load, self)
-          eager_load!
+          config.eager_load_namespaces.each(&:eager_load!)
         end
       end
 
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 40f35ae5a6dcb..3a5caf9f62c76 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -339,11 +339,16 @@ class Engine < Railtie
 
     class << self
       attr_accessor :called_from, :isolated
+
       alias :isolated? :isolated
       alias :engine_name :railtie_name
 
+      delegate :eager_load!, to: :instance
+
       def inherited(base)
         unless base.abstract_railtie?
+          Rails::Railtie::Configuration.eager_load_namespaces << base
+
           base.called_from = begin
             # Remove the line number from backtraces making sure we don't leave anything behind
             call_stack = caller.map { |p| p.sub(/:\d+.*/, '') }
diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index 1cb99463cc888..fba685c769a03 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -178,9 +178,6 @@ def config
       @config ||= Railtie::Configuration.new
     end
 
-    def eager_load!
-    end
-
     def railtie_namespace
       @railtie_namespace ||= self.class.parents.detect { |n| n.respond_to?(:railtie_namespace) }
     end
diff --git a/railties/lib/rails/railtie/configuration.rb b/railties/lib/rails/railtie/configuration.rb
index 1c6b3769a5a5b..9dc8843887f8b 100644
--- a/railties/lib/rails/railtie/configuration.rb
+++ b/railties/lib/rails/railtie/configuration.rb
@@ -7,6 +7,16 @@ def initialize
         @@options ||= {}
       end
 
+      # Expose the eager_load_namespaces at "module" level for convenience.
+      def self.eager_load_namespaces #:nodoc:
+        @@eager_load_namespaces ||= []
+      end
+
+      # All namespaces that are eager loaded
+      def eager_load_namespaces
+        @@eager_load_namespaces ||= []
+      end
+
       # Add files that should be watched for change.
       def watchable_files
         @@watchable_files ||= []
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index eb808f5473797..26f8aad95bfe9 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -176,22 +176,6 @@ def teardown
       end
     end
 
-    test "frameworks are not preloaded by default" do
-      require "#{app_path}/config/environment"
-
-      assert ActionController.autoload?(:Caching)
-    end
-
-    test "frameworks are preloaded with config.preload_frameworks is set" do
-      add_to_config <<-RUBY
-        config.preload_frameworks = true
-      RUBY
-
-      require "#{app_path}/config/environment"
-
-      assert !ActionView.autoload?(:AssetPaths)
-    end
-
     test "filter_parameters should be able to set via config.filter_parameters" do
       add_to_config <<-RUBY
         config.filter_parameters += [ :foo, 'bar', lambda { |key, value|
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index 5d7fa7e397664..b05fe3aed547a 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -75,7 +75,6 @@ def world
       RUBY
 
       output = Dir.chdir(app_path){ `rake do_nothing` }
-      puts output
       assert_match "Hello world", output
     end