diff --git a/Gemfile.lock b/Gemfile.lock
index 137d6e368b..7cd4832b3a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -27,7 +27,7 @@ GIT
 
 GIT
   remote: git://github.com/rack/rack.git
-  revision: be777e06bf4de18a7786af1e44647e1498ec1a5d
+  revision: c94e22401d4719b4d78378c7b63362cd692f9005
   specs:
     rack (2.0.0.alpha)
       json
@@ -79,7 +79,7 @@ GIT
 
 GIT
   remote: git://github.com/rails/sprockets.git
-  revision: 653de5268ba862ea23457291824180c67ad5dc99
+  revision: a61550db7184fc83964fb983547ff09da9efa9be
   branch: master
   specs:
     sprockets (4.0.0)
@@ -236,7 +236,7 @@ GEM
       resque (~> 1.25)
       rufus-scheduler (~> 3.0)
     rufus-scheduler (3.1.3)
-    sass (3.4.16)
+    sass (3.4.17)
     sdoc (0.4.1)
       json (~> 1.7, >= 1.7.7)
       rdoc (~> 4.0)
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index 4dba0d968f..4748a54550 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -314,11 +314,11 @@ module ActionDispatch
     end
 
     def session=(session) #:nodoc:
-      Session.set @env, session
+      Session.set self, session
     end
 
     def session_options=(options)
-      Session::Options.set @env, options
+      Session::Options.set self, options
     end
 
     # Override Rack's GET method to support indifferent access
diff --git a/actionpack/lib/action_dispatch/middleware/flash.rb b/actionpack/lib/action_dispatch/middleware/flash.rb
index 23da169b22..379e7ffdc5 100644
--- a/actionpack/lib/action_dispatch/middleware/flash.rb
+++ b/actionpack/lib/action_dispatch/middleware/flash.rb
@@ -274,7 +274,7 @@ module ActionDispatch
       req = ActionDispatch::Request.new env
       @app.call(env)
     ensure
-      session    = Request::Session.find(env) || {}
+      session    = Request::Session.find(req) || {}
       flash_hash = req.flash_hash
 
       if flash_hash && (flash_hash.present? || session.key?('flash'))
diff --git a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
index 84df55fd5a..b924df789f 100644
--- a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
@@ -36,6 +36,11 @@ module ActionDispatch
         @default_options.delete(:sidbits)
         @default_options.delete(:secure_random)
       end
+
+      private
+      def make_request(env)
+        ActionDispatch::Request.new env
+      end
     end
 
     module StaleSessionCheck
@@ -65,8 +70,8 @@ module ActionDispatch
     end
 
     module SessionObject # :nodoc:
-      def prepare_session(env)
-        Request::Session.create(self, env, @default_options)
+      def prepare_session(req)
+        Request::Session.create(self, req, @default_options)
       end
 
       def loaded_session?(session)
@@ -81,8 +86,7 @@ module ActionDispatch
 
       private
 
-      def set_cookie(env, session_id, cookie)
-        request = ActionDispatch::Request.new(env)
+      def set_cookie(request, session_id, cookie)
         request.cookie_jar[key] = cookie
       end
     end
diff --git a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
index d8f9614904..e225f356df 100644
--- a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
@@ -71,16 +71,16 @@ module ActionDispatch
         super(app, options.merge!(:cookie_only => true))
       end
 
-      def destroy_session(env, session_id, options)
+      def destroy_session(req, session_id, options)
         new_sid = generate_sid unless options[:drop]
         # Reset hash and Assign the new session id
-        env["action_dispatch.request.unsigned_session_cookie"] = new_sid ? { "session_id" => new_sid } : {}
+        req.set_header("action_dispatch.request.unsigned_session_cookie", new_sid ? { "session_id" => new_sid } : {})
         new_sid
       end
 
-      def load_session(env)
+      def load_session(req)
         stale_session_check! do
-          data = unpacked_cookie_data(env)
+          data = unpacked_cookie_data(req)
           data = persistent_session_id!(data)
           [data["session_id"], data]
         end
@@ -88,20 +88,21 @@ module ActionDispatch
 
       private
 
-      def extract_session_id(env)
+      def extract_session_id(req)
         stale_session_check! do
-          unpacked_cookie_data(env)["session_id"]
+          unpacked_cookie_data(req)["session_id"]
         end
       end
 
-      def unpacked_cookie_data(env)
-        env["action_dispatch.request.unsigned_session_cookie"] ||= begin
-          stale_session_check! do
-            if data = get_cookie(env)
+      def unpacked_cookie_data(req)
+        req.get_header("action_dispatch.request.unsigned_session_cookie") do |k|
+          v = stale_session_check! do
+            if data = get_cookie(req)
               data.stringify_keys!
             end
             data || {}
           end
+          req.set_header k, v
         end
       end
 
@@ -111,21 +112,20 @@ module ActionDispatch
         data
       end
 
-      def set_session(env, sid, session_data, options)
+      def set_session(req, sid, session_data, options)
         session_data["session_id"] = sid
         session_data
       end
 
-      def set_cookie(env, session_id, cookie)
-        cookie_jar(env)[@key] = cookie
+      def set_cookie(request, session_id, cookie)
+        cookie_jar(request)[@key] = cookie
       end
 
-      def get_cookie(env)
-        cookie_jar(env)[@key]
+      def get_cookie(req)
+        cookie_jar(req)[@key]
       end
 
-      def cookie_jar(env)
-        request = ActionDispatch::Request.new(env)
+      def cookie_jar(request)
         request.cookie_jar.signed_or_encrypted
       end
     end
diff --git a/actionpack/lib/action_dispatch/request/session.rb b/actionpack/lib/action_dispatch/request/session.rb
index bae3d909fa..b946ccb49f 100644
--- a/actionpack/lib/action_dispatch/request/session.rb
+++ b/actionpack/lib/action_dispatch/request/session.rb
@@ -11,31 +11,31 @@ module ActionDispatch
       Unspecified = Object.new
       
       # Creates a session hash, merging the properties of the previous session if any
-      def self.create(store, env, default_options)
-        session_was = find env
-        session     = Request::Session.new(store, env)
+      def self.create(store, req, default_options)
+        session_was = find req
+        session     = Request::Session.new(store, req)
         session.merge! session_was if session_was
 
-        set(env, session)
-        Options.set(env, Request::Session::Options.new(store, default_options))
+        set(req, session)
+        Options.set(req, Request::Session::Options.new(store, default_options))
         session
       end
 
-      def self.find(env)
-        env[ENV_SESSION_KEY]
+      def self.find(req)
+        req.get_header ENV_SESSION_KEY
       end
 
-      def self.set(env, session)
-        env[ENV_SESSION_KEY] = session
+      def self.set(req, session)
+        req.set_header ENV_SESSION_KEY, session
       end
 
       class Options #:nodoc:
-        def self.set(env, options)
-          env[ENV_SESSION_OPTIONS_KEY] = options
+        def self.set(req, options)
+          req.set_header ENV_SESSION_OPTIONS_KEY, options
         end
 
-        def self.find(env)
-          env[ENV_SESSION_OPTIONS_KEY]
+        def self.find(req)
+          req.get_header ENV_SESSION_OPTIONS_KEY
         end
 
         def initialize(by, default_options)
@@ -47,9 +47,9 @@ module ActionDispatch
           @delegate[key]
         end
 
-        def id(env)
+        def id(req)
           @delegate.fetch(:id) {
-            @by.send(:extract_session_id, env)
+            @by.send(:extract_session_id, req)
           }
         end
 
@@ -58,26 +58,26 @@ module ActionDispatch
         def values_at(*args); @delegate.values_at(*args); end
       end
 
-      def initialize(by, env)
+      def initialize(by, req)
         @by       = by
-        @env      = env
+        @req      = req
         @delegate = {}
         @loaded   = false
         @exists   = nil # we haven't checked yet
       end
 
       def id
-        options.id(@env)
+        options.id(@req)
       end
 
       def options
-        Options.find @env
+        Options.find @req
       end
 
       def destroy
         clear
         options = self.options || {}
-        @by.send(:destroy_session, @env, options.id(@env), options)
+        @by.send(:destroy_session, @req, options.id(@req), options)
 
         # Load the new sid to be written with the response
         @loaded = false
@@ -181,7 +181,7 @@ module ActionDispatch
 
       def exists?
         return @exists unless @exists.nil?
-        @exists = @by.send(:session_exists?, @env)
+        @exists = @by.send(:session_exists?, @req)
       end
 
       def loaded?
@@ -209,7 +209,7 @@ module ActionDispatch
       end
 
       def load!
-        id, session = @by.load_session @env
+        id, session = @by.load_session @req
         options[:id] = id
         @delegate.replace(stringify_keys(session))
         @loaded = true
diff --git a/actionpack/test/dispatch/request/session_test.rb b/actionpack/test/dispatch/request/session_test.rb
index 8bcc07dd04..410e3194e2 100644
--- a/actionpack/test/dispatch/request/session_test.rb
+++ b/actionpack/test/dispatch/request/session_test.rb
@@ -4,40 +4,42 @@ require 'action_dispatch/middleware/session/abstract_store'
 module ActionDispatch
   class Request
     class SessionTest < ActiveSupport::TestCase
+      attr_reader :req
+
+      def setup
+        @req = ActionDispatch::Request.new({})
+      end
+
       def test_create_adds_itself_to_env
-        env = {}
-        s = Session.create(store, env, {})
-        assert_equal s, env[Rack::RACK_SESSION]
+        s = Session.create(store, req, {})
+        assert_equal s, req.env[Rack::RACK_SESSION]
       end
 
       def test_to_hash
-        env = {}
-        s = Session.create(store, env, {})
+        s = Session.create(store, req, {})
         s['foo'] = 'bar'
         assert_equal 'bar', s['foo']
         assert_equal({'foo' => 'bar'}, s.to_hash)
       end
 
       def test_create_merges_old
-        env = {}
-        s = Session.create(store, env, {})
+        s = Session.create(store, req, {})
         s['foo'] = 'bar'
 
-        s1 = Session.create(store, env, {})
+        s1 = Session.create(store, req, {})
         assert_not_equal s, s1
         assert_equal 'bar', s1['foo']
       end
 
       def test_find
-        env = {}
-        assert_nil Session.find(env)
+        assert_nil Session.find(req)
 
-        s = Session.create(store, env, {})
-        assert_equal s, Session.find(env)
+        s = Session.create(store, req, {})
+        assert_equal s, Session.find(req)
       end
 
       def test_destroy
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.destroy
@@ -46,21 +48,21 @@ module ActionDispatch
       end
 
       def test_keys
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
         assert_equal %w[rails adequate], s.keys
       end
 
       def test_values
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
         assert_equal %w[ftw awesome], s.values
       end
 
       def test_clear
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
         s['adequate'] = 'awesome'
 
@@ -69,7 +71,7 @@ module ActionDispatch
       end
 
       def test_update
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.update(:rails => 'awesome')
@@ -79,7 +81,7 @@ module ActionDispatch
       end
 
       def test_delete
-        s = Session.create(store, {}, {})
+        s = Session.create(store, req, {})
         s['rails'] = 'ftw'
 
         s.delete('rails')
@@ -88,7 +90,7 @@ module ActionDispatch
       end
 
       def test_fetch
-        session = Session.create(store, {}, {})
+        session = Session.create(store, req, {})
 
         session['one'] = '1'
         assert_equal '1', session.fetch(:one)
diff --git a/actionpack/test/dispatch/session/abstract_store_test.rb b/actionpack/test/dispatch/session/abstract_store_test.rb
index fe1a7b4f86..1c35144e6f 100644
--- a/actionpack/test/dispatch/session/abstract_store_test.rb
+++ b/actionpack/test/dispatch/session/abstract_store_test.rb
@@ -27,7 +27,7 @@ module ActionDispatch
         as.call(env)
 
         assert @env
-        assert Request::Session.find @env
+        assert Request::Session.find ActionDispatch::Request.new @env
       end
 
       def test_new_session_object_is_merged_with_old
@@ -36,11 +36,11 @@ module ActionDispatch
         as.call(env)
 
         assert @env
-        session = Request::Session.find @env
+        session = Request::Session.find ActionDispatch::Request.new @env
         session['foo'] = 'bar'
 
         as.call(@env)
-        session1 = Request::Session.find @env
+        session1 = Request::Session.find ActionDispatch::Request.new @env
 
         assert_not_equal session, session1
         assert_equal session.to_hash, session1.to_hash