diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index baaf7f2ddca7b074de45d4bca6f49da691114cee..518d3771b9b39fbb3ea7c7cf0cd20c134229f5d3 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,8 @@
 *SVN*
 
+* Declare file extensions exempt from layouts.  #6219 [brandon]
+    Example: ActionController::Base.exempt_from_layout 'rpdf'
+
 * Add chained replace/update support for assert_select_rjs [Rick Olson]
 
     Given RJS like...
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index f42686c318f7dd9d506ff042e0b2f9ae96990eda..c9719895824cbb729b3b248527a9d7a411efc32a 100755
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -315,6 +315,9 @@ class Base
     # Returns the name of the action this controller is processing.
     attr_accessor :action_name
 
+    # Templates that are exempt from layouts
+    @@exempt_from_layout = Set.new([/\.rjs$/])
+
     class << self
       # Factory for the standard create, process loop where the controller is discarded after processing.
       def process(request, response) #:nodoc:
@@ -395,6 +398,14 @@ def filter_parameter_logging(*filter_words, &block)
           filtered_parameters
         end
       end
+
+      # Don't render layouts for templates with the given extensions.
+      def exempt_from_layout(*extensions)
+        regexps = extensions.collect do |extension|
+          extension.is_a?(Regexp) ? extension : /\.#{Regexp.escape(extension.to_s)}$/
+        end
+        @@exempt_from_layout.merge regexps
+      end
     end
 
     public
@@ -1094,7 +1105,10 @@ def template_public?(template_name = default_template_name)
       end
 
       def template_exempt_from_layout?(template_name = default_template_name)
-        template_name =~ /\.rjs$/ || (@template.pick_template_extension(template_name) == :rjs rescue false)
+        @@exempt_from_layout.any? { |ext| template_name =~ ext } or
+          @template.pick_template_extension(template_name) == :rjs
+      rescue
+        false
       end
 
       def assert_existence_of_template_file(template_name)
diff --git a/actionpack/test/controller/layout_test.rb b/actionpack/test/controller/layout_test.rb
index bbb13d0320666b6232cf9e4159e3c29706f4c6bc..3e1d3d96446f2dfe380c26911f1f6f49a19eaaa3 100644
--- a/actionpack/test/controller/layout_test.rb
+++ b/actionpack/test/controller/layout_test.rb
@@ -72,6 +72,39 @@ def test_namespaced_controllers_auto_detect_layouts
   end
 end
 
+class ExemptFromLayoutTest < Test::Unit::TestCase
+  def setup
+    @controller = LayoutTest.new
+  end
+
+  def test_rjs_exempt_from_layout
+    assert @controller.send(:template_exempt_from_layout?, 'test.rjs')
+  end
+
+  def test_rhtml_and_rxml_not_exempt_from_layout
+    assert !@controller.send(:template_exempt_from_layout?, 'test.rhtml')
+    assert !@controller.send(:template_exempt_from_layout?, 'test.rxml')
+  end
+
+  def test_other_extension_not_exempt_from_layout
+    assert !@controller.send(:template_exempt_from_layout?, 'test.random')
+  end
+
+  def test_add_extension_to_exempt_from_layout
+    ['rpdf', :rpdf].each do |ext|
+      assert_nothing_raised do
+        ActionController::Base.exempt_from_layout ext
+      end
+      assert @controller.send(:template_exempt_from_layout?, "test.#{ext}")
+    end
+  end
+
+  def test_add_regexp_to_exempt_from_layout
+    ActionController::Base.exempt_from_layout /\.rdoc/
+    assert @controller.send(:template_exempt_from_layout?, 'test.rdoc')
+  end
+end
+
 
 class DefaultLayoutController < LayoutTest
 end