diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 0519783d02..793cd53518 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -2,6 +2,7 @@ require 'mail'
 require 'action_mailer/tmail_compat'
 require 'action_mailer/collector'
 require 'active_support/core_ext/array/wrap'
+require 'active_support/core_ext/object/blank'
 
 module ActionMailer #:nodoc:
   # Action Mailer allows you to send email from your application using a mailer model and views.
diff --git a/actionmailer/lib/action_mailer/old_api.rb b/actionmailer/lib/action_mailer/old_api.rb
index c7f341d46c..7c59a8ae50 100644
--- a/actionmailer/lib/action_mailer/old_api.rb
+++ b/actionmailer/lib/action_mailer/old_api.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/object/try'
+require 'active_support/core_ext/object/blank'
 
 module ActionMailer
   module OldApi #:nodoc:
diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index 6ec788f302..424828f7e8 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -1,4 +1,5 @@
 require 'active_support/base64'
+require 'active_support/core_ext/object/blank'
 
 module ActionController
   module HttpAuthentication
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index d906e1fb5b..aebd71e867 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/class/attribute'
+require 'active_support/core_ext/object/blank'
 
 module ActionController
   def self.add_renderer(key, &block)
diff --git a/actionpack/lib/action_controller/railties/log_subscriber.rb b/actionpack/lib/action_controller/railties/log_subscriber.rb
index c2299d0b05..00ac3bdf67 100644
--- a/actionpack/lib/action_controller/railties/log_subscriber.rb
+++ b/actionpack/lib/action_controller/railties/log_subscriber.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionController
   module Railties
     class LogSubscriber < Rails::LogSubscriber
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 120f34460e..306db4a431 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -1,4 +1,5 @@
 require 'rack/session/abstract/id'
+require 'active_support/core_ext/object/blank'
 
 module ActionController
   module TemplateAssertions
diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb
index d2404e63c5..9b9e81440b 100644
--- a/actionpack/lib/action_dispatch/http/cache.rb
+++ b/actionpack/lib/action_dispatch/http/cache.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionDispatch
   module Http
     module Cache
diff --git a/actionpack/lib/action_dispatch/http/filter_parameters.rb b/actionpack/lib/action_dispatch/http/filter_parameters.rb
index e42b4d09b0..152aaa2e67 100644
--- a/actionpack/lib/action_dispatch/http/filter_parameters.rb
+++ b/actionpack/lib/action_dispatch/http/filter_parameters.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/hash/keys'
+require 'active_support/core_ext/object/duplicable'
 
 module ActionDispatch
   module Http
diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 3f1a77295d..d6a805bf3b 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -1,5 +1,6 @@
 require 'set'
 require 'active_support/core_ext/class/attribute_accessors'
+require 'active_support/core_ext/object/blank'
 
 module Mime
   class Mimes < Array
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 9cfe5a5ea9..362e5ec970 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -1,5 +1,6 @@
 require 'digest/md5'
 require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/object/blank'
 
 module ActionDispatch # :nodoc:
   # Represents an HTTP response generated by a controller action. One can use
diff --git a/actionpack/lib/action_dispatch/http/upload.rb b/actionpack/lib/action_dispatch/http/upload.rb
index dc6121b911..81d2517304 100644
--- a/actionpack/lib/action_dispatch/http/upload.rb
+++ b/actionpack/lib/action_dispatch/http/upload.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionDispatch
   module Http
     module UploadedFile
diff --git a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
index 311880cabc..dddedc832f 100644
--- a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
@@ -1,5 +1,6 @@
 require 'rack/utils'
 require 'rack/request'
+require 'active_support/core_ext/object/blank'
 
 module ActionDispatch
   module Session
diff --git a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
index 22da82479e..3331b7c25e 100644
--- a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/hash/keys'
+require 'active_support/core_ext/object/blank'
 
 module ActionDispatch
   module Session
diff --git a/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb b/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
index dd650e83d9..b0545279b1 100644
--- a/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionDispatch
   module Routing
     class RouteSet
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 5a3868e1d4..26f0e14e72 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/hash/except'
+require 'active_support/core_ext/object/blank'
 
 module ActionDispatch
   module Routing
diff --git a/actionpack/lib/action_dispatch/testing/performance_test.rb b/actionpack/lib/action_dispatch/testing/performance_test.rb
index 1b9a6c18b7..33a5c68b9d 100644
--- a/actionpack/lib/action_dispatch/testing/performance_test.rb
+++ b/actionpack/lib/action_dispatch/testing/performance_test.rb
@@ -1,7 +1,7 @@
 require 'active_support/testing/performance'
 require 'active_support/testing/default'
 
-if defined?(ActiveSupport::Testing::Performance)
+begin
   module ActionDispatch
     # An integration test that runs a code profiler on your test methods.
     # Profiling output for combinations of each test method, measurement, and
@@ -14,4 +14,6 @@ if defined?(ActiveSupport::Testing::Performance)
       include ActiveSupport::Testing::Default
     end
   end
+rescue NameError
+  $stderr.puts "Specify ruby-prof as application's dependency in Gemfile to run benchmarks."
 end
\ No newline at end of file
diff --git a/actionpack/lib/action_dispatch/testing/test_request.rb b/actionpack/lib/action_dispatch/testing/test_request.rb
index 20288aa7a5..090e03cf44 100644
--- a/actionpack/lib/action_dispatch/testing/test_request.rb
+++ b/actionpack/lib/action_dispatch/testing/test_request.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionDispatch
   class TestRequest < Request
     DEFAULT_ENV = Rack::MockRequest.env_for('/')
diff --git a/actionpack/lib/action_view/helpers/capture_helper.rb b/actionpack/lib/action_view/helpers/capture_helper.rb
index f0be814700..20598237e9 100644
--- a/actionpack/lib/action_view/helpers/capture_helper.rb
+++ b/actionpack/lib/action_view/helpers/capture_helper.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionView
   module Helpers
     # CaptureHelper exposes methods to let you extract generated markup which
diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 2ba5339b7d..7b5b3ae000 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -4,6 +4,7 @@ require 'action_view/helpers/tag_helper'
 require 'action_view/helpers/form_tag_helper'
 require 'active_support/core_ext/class/inheritable_attributes'
 require 'active_support/core_ext/hash/slice'
+require 'active_support/core_ext/object/blank'
 
 module ActionView
   module Helpers
diff --git a/actionpack/lib/action_view/helpers/form_options_helper.rb b/actionpack/lib/action_view/helpers/form_options_helper.rb
index 4c523d4b20..11c6351bd3 100644
--- a/actionpack/lib/action_view/helpers/form_options_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_options_helper.rb
@@ -1,6 +1,7 @@
 require 'cgi'
 require 'erb'
 require 'action_view/helpers/form_helper'
+require 'active_support/core_ext/object/blank'
 
 module ActionView
   module Helpers
diff --git a/actionpack/lib/action_view/helpers/form_tag_helper.rb b/actionpack/lib/action_view/helpers/form_tag_helper.rb
index 07694f5ebb..ca100e102e 100644
--- a/actionpack/lib/action_view/helpers/form_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_tag_helper.rb
@@ -1,6 +1,7 @@
 require 'cgi'
 require 'action_view/helpers/tag_helper'
 require 'active_support/core_ext/object/returning'
+require 'active_support/core_ext/object/blank'
 
 module ActionView
   module Helpers
diff --git a/actionpack/lib/action_view/helpers/number_helper.rb b/actionpack/lib/action_view/helpers/number_helper.rb
index 719b64b940..605e5d5873 100644
--- a/actionpack/lib/action_view/helpers/number_helper.rb
+++ b/actionpack/lib/action_view/helpers/number_helper.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/big_decimal/conversions'
 require 'active_support/core_ext/float/rounding'
+require 'active_support/core_ext/object/blank'
 
 module ActionView
   module Helpers #:nodoc:
diff --git a/actionpack/lib/action_view/helpers/prototype_helper.rb b/actionpack/lib/action_view/helpers/prototype_helper.rb
index ccdc8181db..ebe0b4e876 100644
--- a/actionpack/lib/action_view/helpers/prototype_helper.rb
+++ b/actionpack/lib/action_view/helpers/prototype_helper.rb
@@ -1,6 +1,7 @@
 require 'set'
 require 'active_support/json'
 require 'active_support/core_ext/object/returning'
+require 'active_support/core_ext/object/blank'
 
 module ActionView
   module Helpers
diff --git a/actionpack/lib/action_view/helpers/tag_helper.rb b/actionpack/lib/action_view/helpers/tag_helper.rb
index 9b4cacd4d7..c09d01eeee 100644
--- a/actionpack/lib/action_view/helpers/tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/tag_helper.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/object/blank'
 require 'set'
 
 module ActionView
diff --git a/actionpack/lib/action_view/helpers/text_helper.rb b/actionpack/lib/action_view/helpers/text_helper.rb
index 27be1690dd..0e1bc139ff 100644
--- a/actionpack/lib/action_view/helpers/text_helper.rb
+++ b/actionpack/lib/action_view/helpers/text_helper.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/object/blank'
 require 'action_view/helpers/tag_helper'
 
 module ActionView
diff --git a/actionpack/lib/action_view/render/partials.rb b/actionpack/lib/action_view/render/partials.rb
index 17d16556b9..f04a89c1ac 100644
--- a/actionpack/lib/action_view/render/partials.rb
+++ b/actionpack/lib/action_view/render/partials.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionView
   # There's also a convenience method for rendering sub templates within the current controller that depends on a
   # single object (we call this kind of sub templates for partials). It relies on the fact that partials should
diff --git a/actionpack/lib/action_view/test_case.rb b/actionpack/lib/action_view/test_case.rb
index b0ababe344..23b0c6e121 100644
--- a/actionpack/lib/action_view/test_case.rb
+++ b/actionpack/lib/action_view/test_case.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/object/blank'
 require 'action_controller/test_case'
 require 'action_view'
 
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index cb67ef7270..2d5acdfced 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -1,4 +1,7 @@
+require 'active_model/attribute_methods'
+require 'active_support/concern'
 require 'active_support/hash_with_indifferent_access'
+require 'active_support/core_ext/object/duplicable'
 
 module ActiveModel
   # <tt>ActiveModel::Dirty</tt> provides a way to track changes in your
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index a9a54a90e0..8d28040c32 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/string/inflections'
+require 'active_support/core_ext/object/blank'
 require 'active_support/ordered_hash'
 
 module ActiveModel
diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index b7c52be3f0..906d239bcc 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/array/wrap'
 require "active_support/core_ext/module/anonymous"
+require 'active_support/core_ext/object/blank'
 
 module ActiveModel #:nodoc:
   # A simple base class that can be used along with 
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index d623ddb915..ee87cb9b41 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/module/delegation'
 require 'active_support/core_ext/enumerable'
+require 'active_support/core_ext/object/blank'
 
 module ActiveRecord
   class InverseOfAssociationNotFoundError < ActiveRecordError #:nodoc:
@@ -85,6 +86,15 @@ module ActiveRecord
     end
   end
 
+  # This error is raised when trying to destroy a parent instance in a N:1, 1:1 assosications
+  # (has_many, has_one) when there is at least 1 child assosociated instance.
+  # ex: if @project.tasks.size > 0, DeleteRestrictionError will be raised when trying to destroy @project
+  class DeleteRestrictionError < ActiveRecordError #:nodoc:
+    def initialize(reflection)
+      super("Cannot delete record because of dependent #{reflection.name}")
+    end
+  end
+
   # See ActiveRecord::Associations::ClassMethods for documentation.
   module Associations # :nodoc:
     extend ActiveSupport::Concern
@@ -830,6 +840,8 @@ module ActiveRecord
       #   objects are deleted *without* calling their +destroy+ method.  If set to <tt>:nullify</tt> all associated
       #   objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. *Warning:* This option is ignored when also using
       #   the <tt>:through</tt> option.
+      #   the <tt>:through</tt> option. If set to <tt>:restrict</tt>
+      #   this object cannot be deleted if it has any associated object.
       # [:finder_sql]
       #   Specify a complete SQL statement to fetch the association. This is a good way to go for complex
       #   associations that depend on multiple tables. Note: When this option is used, +find_in_collection+ is _not_ added.
@@ -1468,9 +1480,15 @@ module ActiveRecord
 
         # Creates before_destroy callback methods that nullify, delete or destroy
         # has_many associated objects, according to the defined :dependent rule.
+        # If the association is marked as :dependent => :restrict, create a callback
+        # that prevents deleting entirely.
         #
         # See HasManyAssociation#delete_records.  Dependent associations
         # delete children, otherwise foreign key is set to NULL.
+        # See HasManyAssociation#delete_records. Dependent associations
+        # delete children if the option is set to :destroy or :delete_all, set the
+        # foreign key to NULL if the option is set to :nullify, and do not touch the
+        # child records if the option is set to :restrict.
         #
         # The +extra_conditions+ parameter, which is not used within the main
         # Active Record codebase, is meant to allow plugins to define extra
@@ -1530,14 +1548,24 @@ module ActiveRecord
                       %@#{dependent_conditions}@)
                   end
                 CALLBACK
+                when :restrict
+                  method_name = "has_many_dependent_restrict_for_#{reflection.name}".to_sym
+                  define_method(method_name) do
+                    unless send(reflection.name).empty?
+                      raise DeleteRestrictionError.new(reflection)
+                    end
+                  end
+                  before_destroy method_name
               else
-                raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, or :nullify (#{reflection.options[:dependent].inspect})"
+                raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, :nullify or :restrict (#{reflection.options[:dependent].inspect})"
             end
           end
         end
 
         # Creates before_destroy callback methods that nullify, delete or destroy
         # has_one associated objects, according to the defined :dependent rule.
+        # If the association is marked as :dependent => :restrict, create a callback
+        # that prevents deleting entirely.
         def configure_dependency_for_has_one(reflection)
           if reflection.options.include?(:dependent)
             name = reflection.options[:dependent]
@@ -1558,8 +1586,16 @@ module ActiveRecord
                     association.update_attribute(#{reflection.primary_key_name.inspect}, nil) if association
                   end
                 eoruby
+              when :restrict
+                method_name = "has_one_dependent_restrict_for_#{reflection.name}".to_sym
+                define_method(method_name) do
+                  unless send(reflection.name).nil?
+                    raise DeleteRestrictionError.new(reflection)
+                  end
+                end
+                before_destroy method_name
               else
-                raise ArgumentError, "The :dependent option expects either :destroy, :delete or :nullify (#{reflection.options[:dependent].inspect})"
+                raise ArgumentError, "The :dependent option expects either :destroy, :delete, :nullify or :restrict (#{reflection.options[:dependent].inspect})"
             end
 
             before_destroy method_name
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index bd2acd4340..5338bb099d 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -1,4 +1,5 @@
 require "active_record/associations/through_association_scope"
+require 'active_support/core_ext/object/blank'
 
 module ActiveRecord
   module Associations
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index a8698a2f5a..435aea9b09 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module AttributeMethods
     module Dirty
diff --git a/activerecord/lib/active_record/attribute_methods/query.rb b/activerecord/lib/active_record/attribute_methods/query.rb
index a949d80120..948809c65a 100644
--- a/activerecord/lib/active_record/attribute_methods/query.rb
+++ b/activerecord/lib/active_record/attribute_methods/query.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module AttributeMethods
     module Query
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 367b4ce217..b81434c1f7 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -13,6 +13,8 @@ require 'active_support/core_ext/hash/slice'
 require 'active_support/core_ext/string/behavior'
 require 'active_support/core_ext/object/singleton_class'
 require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/object/duplicable'
+require 'active_support/core_ext/object/blank'
 require 'arel'
 require 'active_record/errors'
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
index 020acbbe5a..1e095110f2 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/duplicable'
+
 module ActiveRecord
   module ConnectionAdapters # :nodoc:
     module QueryCache
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 64faaef4a0..046825d43f 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/object/blank'
 require 'date'
 require 'set'
 require 'bigdecimal'
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 521bd810d0..55d9d20bb5 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -1,5 +1,6 @@
 require 'active_record/connection_adapters/abstract_adapter'
 require 'active_support/core_ext/kernel/requires'
+require 'active_support/core_ext/object/blank'
 require 'set'
 
 module MysqlCompat #:nodoc:
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 31d5266da8..2ae26246a2 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -1,5 +1,6 @@
 require 'active_record/connection_adapters/abstract_adapter'
 require 'active_support/core_ext/kernel/requires'
+require 'active_support/core_ext/object/blank'
 
 begin
   require_library_or_gem 'pg'
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 79f70f07cd..22f0e60083 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -4,6 +4,7 @@ require 'csv'
 require 'zlib'
 require 'active_support/dependencies'
 require 'active_support/core_ext/logger'
+require 'active_support/core_ext/object/blank'
 
 if RUBY_VERSION < '1.9'
   module YAML #:nodoc:
diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 394e1587e1..11c21a9207 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -1,6 +1,7 @@
 require 'active_support/core_ext/array'
 require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/object/singleton_class'
+require 'active_support/core_ext/object/blank'
 
 module ActiveRecord
   module NamedScope
diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb
index 76ec7eb681..ee2d420194 100644
--- a/activerecord/lib/active_record/nested_attributes.rb
+++ b/activerecord/lib/active_record/nested_attributes.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/object/try'
+require 'active_support/core_ext/object/blank'
 
 module ActiveRecord
   module NestedAttributes #:nodoc:
diff --git a/activerecord/lib/active_record/query_cache.rb b/activerecord/lib/active_record/query_cache.rb
index eb92bc2545..093c6c1e55 100644
--- a/activerecord/lib/active_record/query_cache.rb
+++ b/activerecord/lib/active_record/query_cache.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   class QueryCache
     module ClassMethods
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index a20c152eeb..8577ec58f7 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   class Relation
     JoinOperation = Struct.new(:relation, :join_class, :on)
diff --git a/activerecord/lib/active_record/relation/batches.rb b/activerecord/lib/active_record/relation/batches.rb
index 4a260d4caa..cb57b445e5 100644
--- a/activerecord/lib/active_record/relation/batches.rb
+++ b/activerecord/lib/active_record/relation/batches.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module Batches # :nodoc:
     # Yields each record that was found by the find +options+. The find is
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index e77424a64b..a5ea6e7e3a 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module Calculations
     # Count operates using three different approaches.
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index c1cce679b6..37aaac0894 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module FinderMethods
     # Find operates with four different retrieval approaches:
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 0250e739b8..e224781016 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module QueryMethods
     extend ActiveSupport::Concern
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 2841ff1239..a17de1bdbb 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   module SpawnMethods
     def merge(r)
diff --git a/activerecord/lib/active_record/schema.rb b/activerecord/lib/active_record/schema.rb
index a996a0ebac..a833356d15 100644
--- a/activerecord/lib/active_record/schema.rb
+++ b/activerecord/lib/active_record/schema.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveRecord
   # Allows programmers to programmatically define a schema in a portable
   # DSL. This means you can define tables, indexes, etc. without using SQL
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 41a23d7f61..163ac025dd 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -439,9 +439,15 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_equal [author_address.id], AuthorAddress.destroyed_author_address_ids
   end
 
-  def test_invalid_belongs_to_dependent_option_raises_exception
+  def test_invalid_belongs_to_dependent_option_nullify_raises_exception
     assert_raise ArgumentError do
       Author.belongs_to :special_author_address, :dependent => :nullify
     end
   end
+  
+  def test_invalid_belongs_to_dependent_option_restrict_raises_exception
+    assert_raise ArgumentError do
+      Author.belongs_to :special_author_address, :dependent => :restrict
+    end
+  end
 end
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 54624e79ce..c1e539d573 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -836,6 +836,14 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal num_accounts, Account.count
   end
 
+  def test_restrict
+    firm = RestrictedFirm.new(:name => 'restrict')
+    firm.save!
+    child_firm = firm.companies.create(:name => 'child')
+    assert !firm.companies.empty?
+    assert_raise(ActiveRecord::DeleteRestrictionError) { firm.destroy }
+  end
+
   def test_included_in_collection
     assert companies(:first_firm).clients.include?(Client.find(2))
   end
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index 7372f2da1b..8f5540950e 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -177,7 +177,15 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert_nothing_raised { firm.destroy }
   end
 
-  def test_succesful_build_association
+  def test_dependence_with_restrict
+    firm = RestrictedFirm.new(:name => 'restrict')
+    firm.save!
+    account = firm.create_account(:credit_limit => 10)
+    assert !firm.account.nil?
+    assert_raise(ActiveRecord::DeleteRestrictionError) { firm.destroy }
+  end
+
+  def test_successful_build_association
     firm = Firm.new("name" => "GlobalMegaCorp")
     firm.save
 
diff --git a/activerecord/test/models/company.rb b/activerecord/test/models/company.rb
index f31d5f87e5..be6dd71e3b 100644
--- a/activerecord/test/models/company.rb
+++ b/activerecord/test/models/company.rb
@@ -95,6 +95,11 @@ class DependentFirm < Company
   has_many :companies, :foreign_key => 'client_of', :dependent => :nullify
 end
 
+class RestrictedFirm < Company
+  has_one :account, :foreign_key => "firm_id", :dependent => :restrict, :order => "id"
+  has_many :companies, :foreign_key => 'client_of', :order => "id", :dependent => :restrict
+end
+
 class Client < Company
   belongs_to :firm, :foreign_key => "client_of"
   belongs_to :firm_with_basic_id, :class_name => "Firm", :foreign_key => "firm_id"
diff --git a/activeresource/lib/active_resource/base.rb b/activeresource/lib/active_resource/base.rb
index 67296a171a..5cfe4f7c7d 100644
--- a/activeresource/lib/active_resource/base.rb
+++ b/activeresource/lib/active_resource/base.rb
@@ -9,6 +9,7 @@ require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/object/misc'
 require 'active_support/core_ext/object/to_query'
+require 'active_support/core_ext/object/duplicable'
 require 'set'
 require 'uri'
 
diff --git a/activeresource/lib/active_resource/custom_methods.rb b/activeresource/lib/active_resource/custom_methods.rb
index ff14b49b07..dd3e35dfc7 100644
--- a/activeresource/lib/active_resource/custom_methods.rb
+++ b/activeresource/lib/active_resource/custom_methods.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/blank'
+
 module ActiveResource
   # A module to support custom REST methods and sub-resources, allowing you to break out
   # of the "default" REST methods with your own custom resource requests.  For example,
diff --git a/activeresource/lib/active_resource/validations.rb b/activeresource/lib/active_resource/validations.rb
index 4774c6dd22..a19e0d0ac9 100644
--- a/activeresource/lib/active_resource/validations.rb
+++ b/activeresource/lib/active_resource/validations.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/array/wrap'
+require 'active_support/core_ext/object/blank'
 
 module ActiveResource
   class ResourceInvalid < ClientError  #:nodoc:
diff --git a/activesupport/lib/active_support/xml_mini/libxmlsax.rb b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
index d7b2f4c5be..fe2c1b9349 100644
--- a/activesupport/lib/active_support/xml_mini/libxmlsax.rb
+++ b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
@@ -1,4 +1,5 @@
 require 'libxml'
+require 'active_support/core_ext/object/blank'
 
 # = XmlMini LibXML implementation using a SAX-based parser
 module ActiveSupport
diff --git a/activesupport/lib/active_support/xml_mini/nokogirisax.rb b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
index d538a9110f..8af7b5e565 100644
--- a/activesupport/lib/active_support/xml_mini/nokogirisax.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
@@ -1,4 +1,5 @@
 require 'nokogiri'
+require 'active_support/core_ext/object/blank'
 
 # = XmlMini Nokogiri implementation using a SAX-based parser
 module ActiveSupport
diff --git a/railties/lib/rails/generators/rails/app/templates/test/performance/browsing_test.rb b/railties/lib/rails/generators/rails/app/templates/test/performance/browsing_test.rb
index a3dc38d9e4..867fc8c985 100644
--- a/railties/lib/rails/generators/rails/app/templates/test/performance/browsing_test.rb
+++ b/railties/lib/rails/generators/rails/app/templates/test/performance/browsing_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 require 'rails/performance_test_help'
 
 # Profiling results for each test method are written to tmp/performance.
-class BrowsingTest < ActionController::PerformanceTest
+class BrowsingTest < ActionDispatch::PerformanceTest
   def test_homepage
     get '/'
   end
diff --git a/railties/lib/rails/generators/rails/resource/resource_generator.rb b/railties/lib/rails/generators/rails/resource/resource_generator.rb
index 1e78945a7e..8a46708009 100644
--- a/railties/lib/rails/generators/rails/resource/resource_generator.rb
+++ b/railties/lib/rails/generators/rails/resource/resource_generator.rb
@@ -1,5 +1,6 @@
 require 'rails/generators/resource_helpers'
 require 'rails/generators/rails/model/model_generator'
+require 'active_support/core_ext/object/blank'
 
 module Rails
   module Generators