diff --git a/actionpack/lib/sprockets/helpers/rails_helper.rb b/actionpack/lib/sprockets/helpers/rails_helper.rb
index 4fb8d0af37..50a8db4000 100644
--- a/actionpack/lib/sprockets/helpers/rails_helper.rb
+++ b/actionpack/lib/sprockets/helpers/rails_helper.rb
@@ -70,9 +70,10 @@ module Sprockets
 
     private
       def debug_assets?
-        params[:debug_assets] == '1' ||
-        params[:debug_assets] == 'true' ||
-        Rails.application.config.assets.debug
+        Rails.application.config.assets.allow_debugging &&
+         (Rails.application.config.assets.debug ||
+          params[:debug_assets] == '1' ||
+          params[:debug_assets] == 'true')
       end
 
       # Override to specify an alternative prefix for asset path generation.
diff --git a/actionpack/test/template/sprockets_helper_test.rb b/actionpack/test/template/sprockets_helper_test.rb
index cac277cf11..5b4023809d 100644
--- a/actionpack/test/template/sprockets_helper_test.rb
+++ b/actionpack/test/template/sprockets_helper_test.rb
@@ -157,6 +157,7 @@ class SprocketsHelperTest < ActionView::TestCase
     assert_match %r{<script src="/assets/xmlhr-[0-9a-f]+.js\?body=1" type="text/javascript"></script>\n<script src="/assets/application-[0-9a-f]+.js\?body=1" type="text/javascript"></script>},
       javascript_include_tag(:application, :debug => true)
 
+    @config.assets.allow_debugging = true
     @config.assets.debug = true
     assert_match %r{<script src="/assets/xmlhr-[0-9a-f]+.js\?body=1" type="text/javascript"></script>\n<script src="/assets/application-[0-9a-f]+.js\?body=1" type="text/javascript"></script>},
       javascript_include_tag(:application)
@@ -197,6 +198,7 @@ class SprocketsHelperTest < ActionView::TestCase
     assert_match %r{<link href="/assets/style-[0-9a-f]+.css\?body=1" media="screen" rel="stylesheet" type="text/css" />\n<link href="/assets/application-[0-9a-f]+.css\?body=1" media="screen" rel="stylesheet" type="text/css" />},
       stylesheet_link_tag(:application, :debug => true)
 
+    @config.assets.allow_debugging = true
     @config.assets.debug = true
     assert_match %r{<link href="/assets/style-[0-9a-f]+.css\?body=1" media="screen" rel="stylesheet" type="text/css" />\n<link href="/assets/application-[0-9a-f]+.css\?body=1" media="screen" rel="stylesheet" type="text/css" />},
       stylesheet_link_tag(:application)
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index f1add68890..c4a02ba5c0 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -33,12 +33,13 @@ module Rails
         @cache_store                 = [ :file_store, "#{root}/tmp/cache/" ]
 
         @assets = ActiveSupport::OrderedOptions.new
-        @assets.enabled    = false
-        @assets.paths      = []
-        @assets.precompile = [ /\w+\.(?!js|css).+/, /application.(css|js)$/ ]
-        @assets.prefix     = "/assets"
-        @assets.version    = ''
-        @assets.debug      = false
+        @assets.enabled         = false
+        @assets.paths           = []
+        @assets.precompile      = [ /\w+\.(?!js|css).+/, /application.(css|js)$/ ]
+        @assets.prefix          = "/assets"
+        @assets.version         = ''
+        @assets.debug           = false
+        @assets.allow_debugging = false
 
         @assets.cache_store    = [ :file_store, "#{root}/tmp/cache/assets/" ]
         @assets.js_compressor  = nil
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 47078e3af9..33f9939ffe 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
@@ -30,6 +30,9 @@
   # Do not compress assets
   config.assets.compress = false
 
+  # Allow pass debug_assets=true as a query parameter to load pages with unpackaged assets
+  config.assets.allow_debugging = true
+
   # Expands the lines which load the assets
   config.assets.debug = true
 end
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 80198cc21e..8e33a65b2d 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
@@ -41,4 +41,7 @@
 
   # Print deprecation notices to the stderr
   config.active_support.deprecation = :stderr
+
+  # Allow pass debug_assets=true as a query parameter to load pages with unpackaged assets
+  config.assets.allow_debugging = true
 end
diff --git a/railties/test/application/assets_test.rb b/railties/test/application/assets_test.rb
index a8d1382e94..1e6a93dbdf 100644
--- a/railties/test/application/assets_test.rb
+++ b/railties/test/application/assets_test.rb
@@ -135,5 +135,47 @@ module ApplicationTests
       assert_match "alert();", last_response.body
       assert_equal 200, last_response.status
     end
+
+    test "assets are concatenated when debug is off and allow_debugging is off either if debug_assets param is provided" do
+      app_with_assets_in_view
+
+      # config.assets.debug and config.assets.allow_debugging are false for production environment
+      ENV["RAILS_ENV"] = "production"
+      require "#{app_path}/config/environment"
+
+      class ::PostsController < ActionController::Base ; end
+
+      # the debug_assets params isn't used if allow_debugging is off
+      get '/posts?debug_assets=true'
+      assert_match /<script src="\/assets\/application-([0-z]+)\.js" type="text\/javascript"><\/script>/, last_response.body
+      assert_not_match /<script src="\/assets\/xmlhr-([0-z]+)\.js" type="text\/javascript"><\/script>/, last_response.body
+    end
+
+    test "assets aren't concatened when allow_debugging is on and debug_assets params is true" do
+      app_with_assets_in_view
+      app_file "config/initializers/allow_debugging.rb", "Rails.application.config.assets.allow_debugging = true"
+
+      ENV["RAILS_ENV"] = "production"
+      require "#{app_path}/config/environment"
+
+      class ::PostsController < ActionController::Base ; end
+
+      get '/posts?debug_assets=true'
+      assert_match /<script src="\/assets\/application-([0-z]+)\.js\?body=1" type="text\/javascript"><\/script>/, last_response.body
+      assert_match /<script src="\/assets\/xmlhr-([0-z]+)\.js\?body=1" type="text\/javascript"><\/script>/, last_response.body
+    end
+
+    private
+    def app_with_assets_in_view
+      app_file "app/assets/javascripts/application.js", "//= require_tree ."
+      app_file "app/assets/javascripts/xmlhr.js", "function f1() { alert(); }"
+      app_file "app/views/posts/index.html.erb", "<%= javascript_include_tag 'application' %>"
+
+      app_file "config/routes.rb", <<-RUBY
+        AppTemplate::Application.routes.draw do
+          match '/posts', :to => "posts#index"
+        end
+      RUBY
+    end
   end
 end