diff --git a/src/Symfony/Component/Routing/Loader/Configurator/ImportConfigurator.php b/src/Symfony/Component/Routing/Loader/Configurator/ImportConfigurator.php
index 9057c2a5d0..baacbe9592 100644
--- a/src/Symfony/Component/Routing/Loader/Configurator/ImportConfigurator.php
+++ b/src/Symfony/Component/Routing/Loader/Configurator/ImportConfigurator.php
@@ -40,8 +40,14 @@ class ImportConfigurator
      *
      * @return $this
      */
-    final public function prefix($prefix)
+    final public function prefix($prefix, string $namePrefix = '')
     {
+        if ('' !== $namePrefix) {
+            $this->route->addNamePrefix($namePrefix);
+        }
+        if (!$prefix) {
+            return $this;
+        }
         if (!\is_array($prefix)) {
             $this->route->addPrefix($prefix);
         } else {
diff --git a/src/Symfony/Component/Routing/Loader/Configurator/Traits/RouteTrait.php b/src/Symfony/Component/Routing/Loader/Configurator/Traits/RouteTrait.php
index d3ced4d638..3613f25222 100644
--- a/src/Symfony/Component/Routing/Loader/Configurator/Traits/RouteTrait.php
+++ b/src/Symfony/Component/Routing/Loader/Configurator/Traits/RouteTrait.php
@@ -124,14 +124,4 @@ trait RouteTrait
 
         return $this;
     }
-
-    /**
-     * Adds a prefix to the name of all the routes within the collection.
-     */
-    final public function addNamePrefix(string $prefix): self
-    {
-        $this->route->addNamePrefix($prefix);
-
-        return $this;
-    }
 }
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/php_dsl.php b/src/Symfony/Component/Routing/Tests/Fixtures/php_dsl.php
index 0780c9fa80..0b8fa0a9eb 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/php_dsl.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/php_dsl.php
@@ -15,6 +15,9 @@ return function (RoutingConfigurator $routes) {
         ->prefix('/sub')
         ->requirements(array('id' => '\d+'));
 
+    $routes->import('php_dsl_sub.php')
+        ->prefix('/zub', 'z_');
+
     $routes->add('ouf', '/ouf')
         ->schemes(array('https'))
         ->methods(array('GET'))
diff --git a/src/Symfony/Component/Routing/Tests/Loader/PhpFileLoaderTest.php b/src/Symfony/Component/Routing/Tests/Loader/PhpFileLoaderTest.php
index 378254282f..c0a72b6f81 100644
--- a/src/Symfony/Component/Routing/Tests/Loader/PhpFileLoaderTest.php
+++ b/src/Symfony/Component/Routing/Tests/Loader/PhpFileLoaderTest.php
@@ -106,6 +106,8 @@ class PhpFileLoaderTest extends TestCase
             ->setHost('host')
             ->setRequirements(array('id' => '\d+'))
         );
+        $expectedCollection->add('z_c_bar', new Route('/zub/pub/bar'));
+        $expectedCollection->add('z_c_pub_buz', (new Route('/zub/pub/buz'))->setHost('host'));
         $expectedCollection->add('ouf', (new Route('/ouf'))
             ->setSchemes(array('https'))
             ->setMethods(array('GET'))