diff --git a/actionpack/lib/action_controller/metal/implicit_render.rb b/actionpack/lib/action_controller/metal/implicit_render.rb
index d66b2214cede1cef23b925f9b592e4572e5b4a73..17fcc2fa02a32e4404f63cc627997b43d9492ad5 100644
--- a/actionpack/lib/action_controller/metal/implicit_render.rb
+++ b/actionpack/lib/action_controller/metal/implicit_render.rb
@@ -3,12 +3,27 @@ module ImplicitRender
 
     include BasicImplicitRender
 
+    # Renders the template corresponding to the controller action, if it exists.
+    # The action name, format, and variant are all taken into account.
+    # For example, the "new" action with an HTML format and variant "phone" 
+    # would try to render the <tt>new.html+phone.erb</tt> template.
+    #
+    # If no template is found <tt>ActionController::BasicImplicitRender</tt>'s implementation is called, unless
+    # a block is passed. In that case, it will override the super implementation.
+    #
+    #   default_render do
+    #     head 404 # No template was found
+    #   end
     def default_render(*args)
       if template_exists?(action_name.to_s, _prefixes, variants: request.variant)
         render(*args)
       else
-        logger.info "No template found for #{self.class.name}\##{action_name}, rendering head :no_content" if logger
-        super
+        if block_given?
+          yield(*args)
+        else
+          logger.info "No template found for #{self.class.name}\##{action_name}, rendering head :no_content" if logger
+          super
+        end
       end
     end
 
diff --git a/actionpack/test/controller/mime/respond_to_test.rb b/actionpack/test/controller/mime/respond_to_test.rb
index 7aef8a50ce1b6f145cf2f077ee629bdbb02434a1..8591bdb4d9584e79092701e941285dec58bba349 100644
--- a/actionpack/test/controller/mime/respond_to_test.rb
+++ b/actionpack/test/controller/mime/respond_to_test.rb
@@ -793,3 +793,24 @@ def test_variant_negotiation_without_block
     assert_equal "phone", @response.body
   end
 end
+
+class RespondToWithBlockOnDefaultRenderController < ActionController::Base
+  def show
+    default_render do
+      render text: 'default_render yielded'
+    end
+  end
+end
+
+class RespondToWithBlockOnDefaultRenderControllerTest < ActionController::TestCase
+  def setup
+    super
+    @request.host = "www.example.com"
+  end
+
+  def test_default_render_uses_block_when_no_template_exists
+    get :show
+    assert_equal "default_render yielded", @response.body
+    assert_equal "text/html", @response.content_type
+  end
+end