diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index e9fc5208b..a38378b27 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -116,13 +116,30 @@ EOF;
         }
 
         // flatten array
+        $classMap = array();
         $autoloads['classmap'] = new \RecursiveIteratorIterator(new \RecursiveArrayIterator($autoloads['classmap']));
+        foreach ($autoloads['psr-0'] as $namespace => $paths) {
+            foreach ($paths as $dir) {
+                $dir = $this->getPath($filesystem, $relVendorPath, $vendorPath, $dir);
+                foreach (ClassMapGenerator::createMap($dir) as $class => $path) {
+                    if (0 === strpos($class, $namespace)) {
+                        $path = '/'.$filesystem->findShortestPath(getcwd(), $path, true);
+                        if (!isset($classMap[$class])) {
+                            $classMap[$class] = '$baseDir . '.var_export($path, true).",\n";
+                        }
+                    }
+                }
+            }
+        }
         foreach ($autoloads['classmap'] as $dir) {
             foreach (ClassMapGenerator::createMap($dir) as $class => $path) {
                 $path = '/'.$filesystem->findShortestPath(getcwd(), $path, true);
-                $classmapFile .= '    '.var_export($class, true).' => $baseDir . '.var_export($path, true).",\n";
+                $classMap[$class] = '$baseDir . '.var_export($path, true).",\n";
             }
         }
+        foreach ($classMap as $class => $code) {
+            $classmapFile .= '    '.var_export($class, true).' => '.$code;
+        }
         $classmapFile .= ");\n";
 
         $filesCode = "";
@@ -279,6 +296,20 @@ EOF;
         return $baseDir.var_export($path, true);
     }
 
+    protected function getPath(Filesystem $filesystem, $relVendorPath, $vendorPath, $path)
+    {
+        $path = strtr($path, '\\', '/');
+        if (!$filesystem->isAbsolutePath($path)) {
+            if (strpos($path, $relVendorPath) === 0) {
+                // path starts with vendor dir
+                return $vendorPath . substr($path, strlen($relVendorPath));
+            }
+            return getcwd().'/'.$path;
+        }
+
+        return $path;
+    }
+
     protected function getAutoloadFile($vendorPathToTargetDirCode, $suffix)
     {
         return <<<AUTOLOAD
@@ -383,4 +414,3 @@ FOOTER;
     }
 
 }
-
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index 7ab1fe127..3343f4bf6 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -33,7 +33,8 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs = new Filesystem;
         $that = $this;
 
-        $this->workingDir = realpath(sys_get_temp_dir());
+        $this->workingDir = realpath(sys_get_temp_dir()).DIRECTORY_SEPARATOR.'cmptest';
+        $this->fs->ensureDirectoryExists($this->workingDir);
         $this->vendorDir = $this->workingDir.DIRECTORY_SEPARATOR.'composer-test-autoload';
         $this->ensureDirectoryExistsAndClear($this->vendorDir);
 
@@ -63,18 +64,14 @@ class AutoloadGeneratorTest extends TestCase
 
     protected function tearDown()
     {
-        if ($this->vendorDir === $this->workingDir) {
-            if (is_dir($this->workingDir.'/composer')) {
-                $this->fs->removeDirectory($this->workingDir.'/composer');
-            }
-        } elseif (is_dir($this->vendorDir)) {
+        chdir($this->dir);
+
+        if (is_dir($this->workingDir)) {
+            $this->fs->removeDirectory($this->workingDir);
+        }
+        if (is_dir($this->vendorDir)) {
             $this->fs->removeDirectory($this->vendorDir);
         }
-        if (is_dir($this->workingDir.'/composersrc')) {
-            $this->fs->removeDirectory($this->workingDir.'/composersrc');
-        }
-
-        chdir($this->dir);
     }
 
     public function testMainPackageAutoloading()
@@ -89,9 +86,9 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue(array()));
 
-        if (!is_dir($this->vendorDir.'/composer')) {
-            mkdir($this->vendorDir.'/composer');
-        }
+        $this->fs->ensureDirectoryExists($this->workingDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/src');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/lib');
 
         $this->createClassFile($this->workingDir);
 
@@ -114,9 +111,9 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue(array()));
 
-        if (!is_dir($this->vendorDir.'/composer')) {
-            mkdir($this->vendorDir.'/composer', 0777, true);
-        }
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/src/Main');
+        file_put_contents($this->vendorDir.'/src/Main/Foo.php', '<?php namespace Main; class Foo {}');
 
         $this->createClassFile($this->vendorDir);
 
@@ -138,7 +135,10 @@ class AutoloadGeneratorTest extends TestCase
             ->will($this->returnValue(array()));
 
         $this->vendorDir .= '/subdir';
-        mkdir($this->vendorDir.'/composer', 0777, true);
+
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/src');
+
         $this->createClassFile($this->workingDir);
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', '_3');
         $this->assertAutoloadFiles('main2', $this->vendorDir.'/composer');
@@ -157,6 +157,8 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue(array()));
 
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a');
+
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', 'TargetDir');
         $this->assertFileEquals(__DIR__.'/Fixtures/autoload_target_dir.php', $this->vendorDir.'/autoload.php');
         $this->assertFileEquals(__DIR__.'/Fixtures/autoload_real_target_dir.php', $this->vendorDir.'/composer/autoload_realTargetDir.php');
@@ -177,7 +179,11 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue($packages));
 
-        mkdir($this->vendorDir.'/composer', 0777, true);
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
+
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', '_5');
         $this->assertAutoloadFiles('vendors', $this->vendorDir.'/composer');
         $this->assertTrue(file_exists($this->vendorDir.'/composer/autoload_classmap.php'), "ClassMap file needs to be generated, even if empty.");
@@ -197,10 +203,10 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue($packages));
 
-        @mkdir($this->vendorDir.'/composer', 0777, true);
-        mkdir($this->vendorDir.'/a/a/src', 0777, true);
-        mkdir($this->vendorDir.'/b/b/src', 0777, true);
-        mkdir($this->vendorDir.'/b/b/lib', 0777, true);
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/lib');
         file_put_contents($this->vendorDir.'/a/a/src/a.php', '<?php class ClassMapFoo {}');
         file_put_contents($this->vendorDir.'/b/b/src/b.php', '<?php class ClassMapBar {}');
         file_put_contents($this->vendorDir.'/b/b/lib/c.php', '<?php class ClassMapBaz {}');
@@ -234,10 +240,10 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue($packages));
 
-        @mkdir($this->vendorDir.'/composer', 0777, true);
-        mkdir($this->vendorDir.'/a/a/src', 0777, true);
-        mkdir($this->vendorDir.'/b/b', 0777, true);
-        mkdir($this->vendorDir.'/c/c/foo', 0777, true);
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/c/c/foo');
         file_put_contents($this->vendorDir.'/a/a/src/a.php', '<?php class ClassMapFoo {}');
         file_put_contents($this->vendorDir.'/b/b/test.php', '<?php class ClassMapBar {}');
         file_put_contents($this->vendorDir.'/c/c/foo/test.php', '<?php class ClassMapBaz {}');
@@ -269,8 +275,8 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue($packages));
 
-        mkdir($this->vendorDir.'/a/a', 0777, true);
-        mkdir($this->vendorDir.'/b/b', 0777, true);
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b');
         file_put_contents($this->vendorDir.'/a/a/test.php', '<?php function testFilesAutoloadGeneration1() {}');
         file_put_contents($this->vendorDir.'/b/b/test2.php', '<?php function testFilesAutoloadGeneration2() {}');
 
@@ -289,7 +295,7 @@ class AutoloadGeneratorTest extends TestCase
     public function testOverrideVendorsAutoloading()
     {
         $package = new MemoryPackage('a', '1.0', '1.0');
-        $package->setAutoload(array('psr-0' => array('A\\B' => '/home/deveuser/local-packages/a-a/lib')));
+        $package->setAutoload(array('psr-0' => array('A\\B' => $this->workingDir.'/lib')));
 
         $packages = array();
         $packages[] = $a = new MemoryPackage('a/a', '1.0', '1.0');
@@ -301,9 +307,48 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getPackages')
             ->will($this->returnValue($packages));
 
-        mkdir($this->vendorDir.'/composer', 0777, true);
+        $this->fs->ensureDirectoryExists($this->workingDir.'/lib/A/B');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib/A/B');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
+        file_put_contents($this->workingDir.'/lib/A/B/C.php', '<?php namespace A\\B; class C {}');
+        file_put_contents($this->vendorDir.'/a/a/lib/A/B/C.php', '<?php namespace A\\B; class C {}');
+
+        $workDir = strtr($this->workingDir, '\\', '/');
+        $expectedNamespace = <<<EOF
+<?php
+
+// autoload_namespaces.php generated by Composer
+
+\$vendorDir = dirname(__DIR__);
+\$baseDir = dirname(\$vendorDir);
+
+return array(
+    'B\\\\Sub\\\\Name' => \$vendorDir . '/b/b/src/',
+    'A\\\\B' => array('$workDir/lib', \$vendorDir . '/a/a/lib/'),
+    'A' => \$vendorDir . '/a/a/src/',
+);
+
+EOF;
+
+        $expectedClassmap = <<<EOF
+<?php
+
+// autoload_classmap.php generated by Composer
+
+\$vendorDir = dirname(__DIR__);
+\$baseDir = dirname(\$vendorDir);
+
+return array(
+    'A\\\\B\\\\C' => \$baseDir . '/lib/A/B/C.php',
+);
+
+EOF;
+
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', '_9');
-        $this->assertAutoloadFiles('override_vendors', $this->vendorDir.'/composer');
+        $this->assertEquals($expectedNamespace, file_get_contents($this->vendorDir.'/composer/autoload_namespaces.php'));
+        $this->assertEquals($expectedClassmap, file_get_contents($this->vendorDir.'/composer/autoload_classmap.php'));
     }
 
     public function testIncludePathFileGeneration()
@@ -328,7 +373,7 @@ class AutoloadGeneratorTest extends TestCase
             ->method("getPackages")
             ->will($this->returnValue($packages));
 
-        mkdir($this->vendorDir."/composer", 0777, true);
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
 
         $this->generator->dump($this->config, $this->repository, $package, $this->im, "composer", '_10');
 
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_classmap3.php b/tests/Composer/Test/Autoload/Fixtures/autoload_classmap3.php
index 35f1159c1..75c7cd741 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_classmap3.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_classmap3.php
@@ -6,5 +6,6 @@ $vendorDir = dirname(__DIR__);
 $baseDir = $vendorDir;
 
 return array(
+    'Main\\Foo' => $baseDir . '/src/Main/Foo.php',
     'ClassMapFoo' => $baseDir . '/composersrc/foo.php',
 );
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_override_vendors.php b/tests/Composer/Test/Autoload/Fixtures/autoload_override_vendors.php
deleted file mode 100644
index 934424b5d..000000000
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_override_vendors.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-// autoload_namespaces.php generated by Composer
-
-$vendorDir = dirname(__DIR__);
-$baseDir = dirname($vendorDir);
-
-return array(
-    'B\\Sub\\Name' => $vendorDir . '/b/b/src/',
-    'A\\B' => array('/home/deveuser/local-packages/a-a/lib', $vendorDir . '/a/a/lib/'),
-    'A' => $vendorDir . '/a/a/src/',
-);