diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index ad70e5266..9b8e137ff 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -35,39 +35,56 @@ class AutoloadGenerator
         $this->installationManager = $installationManager;
     }
 
-    public function dump($targetFilename)
+    public function dump($targetDir)
     {
-        $autoloads = $this->parseAutoloads();
+        $autoloadFile = file_get_contents(__DIR__.'/ClassLoader.php');
 
-        $file = file_get_contents(__DIR__.'/ClassLoader.php');
+        $autoloadFile .= <<<'EOF'
 
-        $file .= <<<'EOF'
+// autoload.php generated by Composer
 
-// autoload.php generated by composer
+function init() {
+    $loader = new ClassLoader();
 
-$loader = new ClassLoader();
+    $map = require __DIR__.'/autoload_namespaces.php';
+
+    foreach ($map as $namespace => $path) {
+        $loader->add($namespace, $path);
+    }
+
+    $loader->register();
+
+    return $loader;
+}
+
+return init();
+EOF;
+
+        $namespacesFile = <<<'EOF'
+<?php
+
+// autoload_namespace.php generated by Composer
+
+return array(
 
 EOF;
 
+        $autoloads = $this->parseAutoloads();
+
         if (isset($autoloads['psr-0'])) {
             foreach ($autoloads['psr-0'] as $def) {
                 foreach ($def['mapping'] as $prefix => $path) {
                     $exportedPrefix = var_export($prefix, true);
                     $exportedPath = var_export(($def['path'] ? '/'.$def['path'] : '').'/'.$path, true);
-                    $file .= <<<EOF
-\$loader->add($exportedPrefix, dirname(dirname(__DIR__)).$exportedPath);
-
-EOF;
+                    $namespacesFile .= "    $exportedPrefix => dirname(dirname(__DIR__)).$exportedPath,\n";
                 }
             }
         }
 
-        $file .= <<<'EOF'
-$loader->register();
+        $namespacesFile .= ");\n";
 
-EOF;
-
-        file_put_contents($targetFilename, $file);
+        file_put_contents($targetDir.'/autoload.php', $autoloadFile);
+        file_put_contents($targetDir.'/autoload_namespaces.php', $namespacesFile);
     }
 
     private function parseAutoloads()
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index 96d8f63f9..1f55bc671 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -115,9 +115,9 @@ EOT
 
         $localRepo->write();
 
-        $output->writeln('> Generating autoload.php');
+        $output->writeln('> Generating autoload files');
         $generator = new AutoloadGenerator($localRepo, $composer->getPackage(), $installationManager);
-        $generator->dump('vendor/.composer/autoload.php');
+        $generator->dump('vendor/.composer/');
 
         $output->writeln('> Done');
     }