diff --git a/src/ClassNameMapper.php b/src/ClassNameMapper.php
index 6932aaa..d18c3d8 100644
--- a/src/ClassNameMapper.php
+++ b/src/ClassNameMapper.php
@@ -90,6 +90,23 @@ public static function createFromComposerFile($composerJsonPath = null, $rootPat
         return $classNameMapper;
     }
 
+    /**
+     * @param  string|null $composerAutoloadPath
+     * @return ClassNameMapper
+     */
+    public static function createFromComposerAutoload($composerAutoloadPath = null)
+    {
+        $classNameMapper = new ClassNameMapper();
+
+        if ($composerAutoloadPath === null) {
+            $composerAutoloadPath = __DIR__ . '/../../../autoload.php';
+        }
+
+        $classNameMapper->loadComposerAutoload($composerAutoloadPath);
+
+        return $classNameMapper;
+    }
+
     /**
      *
      * @param string $composerJsonPath Path to the composer file
@@ -121,6 +138,7 @@ public function loadComposerFile($composerJsonPath, $rootPath = null, $useAutolo
 
         if (isset($composer["autoload"]["psr-4"])) {
             $psr4 = $composer["autoload"]["psr-4"];
+
             foreach ($psr4 as $namespace => $paths) {
                 if ($relativePath != null) {
                     if (!is_array($paths)) {
@@ -169,6 +187,27 @@ public function loadComposerFile($composerJsonPath, $rootPath = null, $useAutolo
         return $this;
     }
 
+    /**
+     * @param  string $composerAutoloadPath
+     * @return self
+     */
+    public function loadComposerAutoload($composerAutoloadPath)
+    {
+        if (file_exists($composerAutoloadPath)) {
+            $loader = require $composerAutoloadPath;
+
+            foreach ($loader->getPrefixes() as $namespace => $paths) {
+                $this->registerPsr0Namespace($namespace, $paths);
+            }
+
+            foreach ($loader->getPrefixesPsr4() as $namespace => $paths) {
+                $this->registerPsr4Namespace($namespace, $paths);
+            }
+        }
+
+        return $this;
+    }
+
     /**
      * Given an existing path, convert it to a path relative to a given starting path.
      * Shamelessly borrowed to Symfony :). Thanks guys.
@@ -325,4 +364,4 @@ private static function unfactorizeAutoload(array $autoload) {
     private static function normalizeDirectory($dir) {
         return $dir === '' ? '' : rtrim($dir, '\\/').'/';
     }
-}
\ No newline at end of file
+}
diff --git a/tests/ClassNameMapperTest.php b/tests/ClassNameMapperTest.php
index d4fd073..aca5a74 100644
--- a/tests/ClassNameMapperTest.php
+++ b/tests/ClassNameMapperTest.php
@@ -14,6 +14,15 @@ public function testGetPossibleFiles() {
 
         $this->assertEquals([ 'src/Foo/Bar.php', 'src2/Bar.php' ], $possibleFiles);
 
+        //From autoloader instead of composer.json
+        $mapper = ClassNameMapper::createFromComposerAutoload(__DIR__ . '/Fixtures/test_autoload.php');
+        $possibleFiles = $mapper->getPossibleFileNames('Mouf\\Composer\\ClassNameMapper');
+
+        $this->assertEquals([
+                'src/ClassNameMapper.php'
+            ],
+            $possibleFiles
+        );
     }
 
     public function testUseAutoloadDev() {
diff --git a/tests/Fixtures/test_autoload.php b/tests/Fixtures/test_autoload.php
new file mode 100644
index 0000000..b66f2f0
--- /dev/null
+++ b/tests/Fixtures/test_autoload.php
@@ -0,0 +1,8 @@
+<?php
+
+use Composer\Autoload\ClassLoader;
+
+$classLoader = new ClassLoader();
+$classLoader->setPsr4('Mouf\\Composer\\', ['src/']);
+
+return $classLoader;