diff --git a/includes/kohana/system/classes/kohana/core.php b/includes/kohana/system/classes/kohana/core.php
index fbc1e99c..b74d0119 100644
--- a/includes/kohana/system/classes/kohana/core.php
+++ b/includes/kohana/system/classes/kohana/core.php
@@ -191,6 +191,7 @@ class Kohana_Core {
 
 		// Kohana is now initialized
 		Kohana::$_init = TRUE;
+		Kohana::$_paths = Kohana::build_paths();
 
 		if (isset($settings['profile']))
 		{
@@ -370,7 +371,7 @@ class Kohana_Core {
 
 			// Reset internal storage
 			Kohana::$_modules = Kohana::$_files = array();
-			Kohana::$_paths   = array(APPPATH, SYSPATH);
+			Kohana::$_paths   = Kohana::build_paths();
 
 			// Reset file cache status
 			Kohana::$_files_changed = FALSE;
@@ -511,14 +512,15 @@ class Kohana_Core {
 		}
 
 		// Start a new list of include paths, APPPATH first
-		$paths = array(APPPATH);
+		$paths = array();
 
 		foreach ($modules as $name => $path)
 		{
 			if (is_dir($path))
 			{
 				// Add the module to include paths
-				$paths[] = $modules[$name] = realpath($path).DIRECTORY_SEPARATOR;
+				$modules[$name] = realpath($path).DIRECTORY_SEPARATOR;
+				$paths[] = $name;
 			}
 			else
 			{
@@ -527,11 +529,8 @@ class Kohana_Core {
 			}
 		}
 
-		// Finish the include paths by adding SYSPATH
-		$paths[] = SYSPATH;
-
 		// Set the new include paths
-		Kohana::$_paths = $paths;
+		Kohana::$_paths = Kohana::build_paths($paths);
 
 		// Set the current module list
 		Kohana::$_modules = $modules;
@@ -550,6 +549,39 @@ class Kohana_Core {
 		return Kohana::$_modules;
 	}
 
+	public static function build_paths(array $module_paths=array()) {
+		// Start a new list of include paths, APPPATH first
+		$paths = array();
+
+		if (OVERPATH AND is_dir(OVERPATH.'application'))
+			$paths[] = OVERPATH.'application';
+
+		$paths[] = APPPATH;
+
+		// Add our modules
+		foreach ($module_paths as $path)
+		{
+			if (is_dir(MODPATH.$path))
+			{
+				// Add the override path
+				if (OVERPATH AND is_dir(OVERPATH.'modules'.DIRECTORY_SEPARATOR.$path))
+				{
+					$paths[] = realpath(OVERPATH.'modules'.DIRECTORY_SEPARATOR.$path).DIRECTORY_SEPARATOR;
+				}
+				// Add the module to include paths
+				$paths[] = realpath(MODPATH.$path).DIRECTORY_SEPARATOR;
+			}
+		}
+
+		// Finish the include paths by adding SYSPATH
+		if (OVERPATH AND is_dir(OVERPATH.'system'))
+			$paths[] = OVERPATH.'system';
+
+		$paths[] = SYSPATH;
+
+		return $paths;
+	}
+
 	/**
 	 * Returns the the currently active include paths, including the
 	 * application and system paths.
@@ -1355,6 +1387,10 @@ class Kohana_Core {
 		{
 			$file = 'MODPATH'.DIRECTORY_SEPARATOR.substr($file, strlen(MODPATH));
 		}
+		elseif (strpos($file, OVERPATH) === 0)
+		{
+			$file = 'OVERPATH/'.substr($file, strlen(OVERPATH));
+		}
 		elseif (strpos($file, DOCROOT) === 0)
 		{
 			$file = 'DOCROOT'.DIRECTORY_SEPARATOR.substr($file, strlen(DOCROOT));
diff --git a/kh.php b/kh.php
index c6b09632..d8cecc50 100644
--- a/kh.php
+++ b/kh.php
@@ -23,6 +23,12 @@ $modules = 'modules';
  */
 $system = 'system';
 
+/**
+ * This directory in which we can override classes that may not yet be accepted
+ * upstream.
+ */
+$override = 'override';
+
 /**
  * The default extension of resource files. If you change this, all resources
  * must be renamed to use the new extension.
@@ -68,13 +74,22 @@ if ( ! is_dir($modules) AND is_dir(DOCROOT.$modules))
 if ( ! is_dir($system) AND is_dir(DOCROOT.$system))
 	$system = DOCROOT.$system;
 
+// Make the override relative to the docroot
+if ( ! is_dir($override) AND is_dir(DOCROOT.$override))
+	$override = DOCROOT.$override;
+
 // Define the absolute paths for configured directories
 define('APPPATH', realpath($application).DIRECTORY_SEPARATOR);
 define('MODPATH', realpath($modules).DIRECTORY_SEPARATOR);
 define('SYSPATH', realpath($system).DIRECTORY_SEPARATOR);
 
+if (is_dir(realpath($override)))
+	define('OVERPATH', realpath($override).DIRECTORY_SEPARATOR);
+else
+	define('OVERPATH', '');
+
 // Clean up the configuration vars
-unset($application, $modules, $system);
+unset($application, $modules, $system, $override);
 
 if (file_exists('install'.EXT))
 {
@@ -88,11 +103,21 @@ require SYSPATH.'base'.EXT;
 // Load the core Kohana class
 require SYSPATH.'classes/kohana/core'.EXT;
 
-if (is_file(APPPATH.'classes/kohana'.EXT))
+if (is_file(OVERPATH.'application/classes/kohana'.EXT))
+{
+	// Override Application extends the core
+	require OVERPATH.'application/classes/kohana'.EXT;
+}
+elseif (is_file(APPPATH.'classes/kohana'.EXT))
 {
 	// Application extends the core
 	require APPPATH.'classes/kohana'.EXT;
 }
+elseif (is_file(OVERPATH.'system/classes/kohana'.EXT))
+{
+	// Override system extends the core
+	require APPPATH.'system/classes/kohana'.EXT;
+}
 else
 {
 	// Load empty core extension