diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
index 8f5d6b32c8..b159ddba20 100644
--- a/src/Symfony/Component/DependencyInjection/CHANGELOG.md
+++ b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -1,6 +1,12 @@
 CHANGELOG
 =========
 
+2.2.0
+-----
+
+ * added PrependExtensionInterface (to be able to allow extensions to prepend
+   application configuration settings for any Bundle)
+
 2.1.0
 -----
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
index a9beb5b9e2..d2c98314e2 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
@@ -29,6 +29,12 @@ class MergeExtensionConfigurationPass implements CompilerPassInterface
         $definitions = $container->getDefinitions();
         $aliases = $container->getAliases();
 
+        foreach ($container->getExtensions() as $extension) {
+            if ($extension instanceof PrependExtensionInterface) {
+                $extension->prepend($container);
+            }
+        }
+
         foreach ($container->getExtensions() as $name => $extension) {
             if (!$config = $container->getExtensionConfig($name)) {
                 // this extension was not called
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/PrependExtensionInterface.php b/src/Symfony/Component/DependencyInjection/Compiler/PrependExtensionInterface.php
new file mode 100644
index 0000000000..bba1b6cd46
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Compiler/PrependExtensionInterface.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+interface PrependExtensionInterface
+{
+    /**
+     * Allow an extension to prepend the extension configurations.
+     *
+     * @param ContainerBuilder $container
+     */
+    public function prepend(ContainerBuilder $container);
+}
diff --git a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
index 30514cc55d..44200ac061 100644
--- a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
+++ b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
@@ -465,6 +465,21 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
         return $this->extensionConfigs[$name];
     }
 
+    /**
+     * Prepends a config array to the configs of the given extension.
+     *
+     * @param string $name    The name of the extension
+     * @param array  $config  The config to set
+     */
+    public function prependExtensionConfig($name, array $config)
+    {
+        if (!isset($this->extensionConfigs[$name])) {
+            $this->extensionConfigs[$name] = array();
+        }
+
+        array_unshift($this->extensionConfigs[$name], $config);
+    }
+
     /**
      * Compiles the container.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
index c9e6b07847..66658efdeb 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
@@ -548,6 +548,28 @@ class ContainerBuilderTest extends \PHPUnit_Framework_TestCase
         $container->compile();
         $container->setDefinition('a', new Definition());
     }
+
+    /**
+     * @covers Symfony\Component\DependencyInjection\ContainerBuilder::getExtensionConfig
+     * @covers Symfony\Component\DependencyInjection\ContainerBuilder::prependExtensionConfig
+     */
+    public function testExtensionConfig()
+    {
+        $container = new ContainerBuilder();
+
+        $configs = $container->getExtensionConfig('foo');
+        $this->assertEmpty($configs);
+
+        $first = array('foo' => 'bar');
+        $container->prependExtensionConfig('foo', $first);
+        $configs = $container->getExtensionConfig('foo');
+        $this->assertEquals(array($first), $configs);
+
+        $second = array('ding' => 'dong');
+        $container->prependExtensionConfig('foo', $second);
+        $configs = $container->getExtensionConfig('foo');
+        $this->assertEquals(array($second, $first), $configs);
+    }
 }
 
 class FooClass {}
diff --git a/src/Symfony/Component/HttpKernel/.gitignore b/src/Symfony/Component/HttpKernel/.gitignore
index 44de97a36a..38c15605ed 100644
--- a/src/Symfony/Component/HttpKernel/.gitignore
+++ b/src/Symfony/Component/HttpKernel/.gitignore
@@ -1,4 +1,5 @@
 vendor/
 composer.lock
 phpunit.xml
-
+Tests/ProjectContainer.php
+Tests/classes.map
\ No newline at end of file