diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index e0b667969c..fd15879424 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* render :xml and :json preserve custom content types.  #10388 [jmettraux, Chu Yeow]
+
 * Refactor Action View template handlers.  #10437 [Josh Peek]
 
 * Fix DoubleRenderError message and leave out mention of returning false from filters.  Closes #10380 [fcheung]
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index b5c4780f52..f1d416d664 100755
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -873,13 +873,13 @@ module ActionController #:nodoc:
             end            
 
           elsif xml = options[:xml]
-            response.content_type = Mime::XML
+            response.content_type ||= Mime::XML
             render_for_text(xml.respond_to?(:to_xml) ? xml.to_xml : xml, options[:status])
 
           elsif json = options[:json]
             json = json.to_json unless json.is_a?(String)
             json = "#{options[:callback]}(#{json})" unless options[:callback].blank?
-            response.content_type = Mime::JSON
+            response.content_type ||= Mime::JSON
             render_for_text(json, options[:status])
 
           elsif partial = options[:partial]
diff --git a/actionpack/test/controller/render_test.rb b/actionpack/test/controller/render_test.rb
index 7765c62a5e..d3a9ec195c 100644
--- a/actionpack/test/controller/render_test.rb
+++ b/actionpack/test/controller/render_test.rb
@@ -44,6 +44,10 @@ class TestController < ActionController::Base
     render :json => {:hello => 'world'}.to_json, :callback => 'alert'
   end
 
+  def render_json_with_custom_content_type
+    render :json => {:hello => 'world'}.to_json, :content_type => 'text/javascript'
+  end
+
   def render_symbol_json
     render :json => {:hello => 'world'}.to_json
   end
@@ -65,6 +69,10 @@ class TestController < ActionController::Base
     render :template => "test/hello"
   end
 
+  def render_xml_with_custom_content_type
+    render :xml => "<blah/>", :content_type => "application/atomsvc+xml"
+  end
+
   def heading
     head :ok
   end
@@ -199,56 +207,62 @@ class RenderTest < Test::Unit::TestCase
     assert_template "test/hello_world"
   end
 
-  def test_do_with_render
+  def test_render
     get :render_hello_world
     assert_template "test/hello_world"
   end
 
-  def test_do_with_render_from_variable
+  def test_render_from_variable
     get :render_hello_world_from_variable
     assert_equal "hello david", @response.body
   end
 
-  def test_do_with_render_action
+  def test_render_action
     get :render_action_hello_world
     assert_template "test/hello_world"
   end
 
-  def test_do_with_render_action_with_symbol
+  def test_render_action_with_symbol
     get :render_action_hello_world_with_symbol
     assert_template "test/hello_world"
   end
 
-  def test_do_with_render_text
+  def test_render_text
     get :render_text_hello_world
     assert_equal "hello world", @response.body
   end
 
-  def test_do_with_render_json
+  def test_render_json
     get :render_json_hello_world
     assert_equal '{"hello": "world"}', @response.body
     assert_equal 'application/json', @response.content_type
   end
 
-  def test_do_with_render_json_with_callback
+  def test_render_json_with_callback
     get :render_json_hello_world_with_callback
     assert_equal 'alert({"hello": "world"})', @response.body
     assert_equal 'application/json', @response.content_type
   end
 
-  def test_do_with_render_symbol_json
+  def test_render_json_with_custom_content_type
+    get :render_json_with_custom_content_type
+    assert_equal '{"hello": "world"}', @response.body
+    assert_equal 'text/javascript', @response.content_type
+  end
+
+  def test_render_symbol_json
     get :render_symbol_json
     assert_equal '{"hello": "world"}', @response.body
     assert_equal 'application/json', @response.content_type
   end
 
-  def test_do_with_render_custom_code
+  def test_render_custom_code
     get :render_custom_code
     assert_response 404
     assert_equal 'hello world', @response.body
   end
 
-  def test_do_with_render_nothing_with_appendix
+  def test_render_nothing_with_appendix
     get :render_nothing_with_appendix
     assert_response 200
     assert_equal 'appended', @response.body
@@ -269,6 +283,7 @@ class RenderTest < Test::Unit::TestCase
   def test_render_xml
     get :render_xml_hello
     assert_equal "<html>\n  <p>Hello David</p>\n<p>This is grand!</p>\n</html>\n", @response.body
+    assert_equal "application/xml", @response.content_type
   end
 
   def test_render_xml_with_default
@@ -435,6 +450,11 @@ class RenderTest < Test::Unit::TestCase
     assert_equal %(Element.replace("foo", "partial html");), @response.body
   end
 
+  def test_should_render_xml_but_keep_custom_content_type
+    get :render_xml_with_custom_content_type
+    assert_equal "application/atomsvc+xml", @response.content_type
+  end
+
   protected
   
     def etag_for(text)