diff --git a/core/includes/common.inc b/core/includes/common.inc
index eefc05344ca..67a4457876a 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -2141,8 +2141,8 @@ function url($path = NULL, array $options = array()) {
     $path = '';
   }
   elseif (!empty($path) && !$options['alias']) {
-    $language = isset($options['language']) && isset($options['language']->langcode) ? $options['language']->langcode : '';
-    $alias = drupal_get_path_alias($original_path, $language);
+    $langcode = isset($options['language']) && isset($options['language']->langcode) ? $options['language']->langcode : '';
+    $alias = drupal_get_path_alias($original_path, $langcode);
     if ($alias != $original_path) {
       $path = $alias;
     }
diff --git a/core/modules/locale/locale.install b/core/modules/locale/locale.install
index 9d172f9a8d8..d2908c5c83b 100644
--- a/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -5,6 +5,35 @@
  * Install, update and uninstall functions for the locale module.
  */
 
+/**
+ * Implements hook_install().
+ *
+ * Enable URL language negotiation by default in order to have a basic working
+ * system on multilingual sites without needing any preliminary configuration.
+ */
+function locale_install() {
+  require_once DRUPAL_ROOT . '/core/includes/language.inc';
+
+  // We cannot rely on language negotiation hooks here, because locale module is
+  // not enabled yet. Therefore language_negotiation_set() cannot be used.
+  $info = locale_language_negotiation_info();
+  $provider = $info[LOCALE_LANGUAGE_NEGOTIATION_URL];
+  $provider_fields = array('callbacks', 'file', 'cache');
+  $negotiation = array();
+
+  // Store only the needed data.
+  foreach ($provider_fields as $field) {
+    if (isset($provider[$field])) {
+      $negotiation[LOCALE_LANGUAGE_NEGOTIATION_URL][$field] = $provider[$field];
+    }
+  }
+
+  // Enable URL language detection for each (core) configurable language type.
+  foreach (language_types_configurable() as $type) {
+    variable_set("language_negotiation_$type", $negotiation);
+  }
+}
+
 /**
  * Fill in the path prefixes and domains when enabled.
  *
diff --git a/core/modules/locale/locale.test b/core/modules/locale/locale.test
index d5439a94bef..117fdf7c34b 100644
--- a/core/modules/locale/locale.test
+++ b/core/modules/locale/locale.test
@@ -1640,15 +1640,10 @@ class LocalePathFunctionalTest extends DrupalWebTestCase {
     $edit = array( "prefix[$langcode]" => $prefix );
     $this->drupalPost('admin/config/regional/language/configure/url', $edit, t('Save configuration'));
 
-    // Check that the "xx" front page is not available when path prefixes are
-    // not enabled yet.
-    $this->drupalPost('admin/config/regional/language/configure', array(), t('Save settings'));
+    // Check that the "xx" front page is readily available because path prefix
+    // negotiation is pre-configured.
     $this->drupalGet($prefix);
-    $this->assertResponse(404, t('The "xx" front page is not available yet.'));
-
-    // Enable URL language detection and selection.
-    $edit = array('language[enabled][locale-url]' => 1);
-    $this->drupalPost('admin/config/regional/language/configure', $edit, t('Save settings'));
+    $this->assertText(t('Welcome to Drupal'), t('The "xx" front page is readibly available.'));
 
     // Create a node.
     $node = $this->drupalCreateNode(array('type' => 'page'));
@@ -2187,7 +2182,6 @@ class LocaleUILanguageNegotiationTest extends DrupalWebTestCase {
     $edit = array('prefix[en]' => 'en');
     $this->drupalPost('admin/config/regional/language/configure/url', $edit, t('Save configuration'));
 
-
     // Enable browser and URL language detection.
     $edit = array(
       'language[enabled][locale-browser]' => TRUE,
@@ -2205,7 +2199,8 @@ class LocaleUILanguageNegotiationTest extends DrupalWebTestCase {
     // Access the front page without specifying any valid URL language prefix
     // and having as browser language preference a non-default language.
     $http_header = array("Accept-Language: $langcode_browser_fallback;q=1");
-    $this->drupalGet('', array(), $http_header);
+    $language = (object) array('langcode' => '');
+    $this->drupalGet('', array('language' => $language), $http_header);
 
     // Check that the language switcher active link matches the given browser
     // language.
diff --git a/core/modules/path/path.test b/core/modules/path/path.test
index 82eefd88b4f..f74e04401bc 100644
--- a/core/modules/path/path.test
+++ b/core/modules/path/path.test
@@ -297,9 +297,11 @@ class PathLanguageTestCase extends DrupalWebTestCase {
     $this->drupalGet('fr/' . $edit['path[alias]']);
     $this->assertText($french_node->title, 'Alias for French translation works.');
 
-    // Confirm that the alias is returned by url().
+    // Confirm that the alias is returned by url(). Languages are cached on
+    // many levels, and we need to clear those caches.
     drupal_static_reset('language_list');
     drupal_static_reset('locale_url_outbound_alter');
+    drupal_static_reset('locale_language_url_rewrite_url');
     $languages = language_list();
     $url = url('node/' . $french_node->nid, array('language' => $languages[$french_node->language]));
     $this->assertTrue(strpos($url, $edit['path[alias]']), t('URL contains the path alias.'));
diff --git a/core/modules/translation/translation.test b/core/modules/translation/translation.test
index f1457a82184..dd00734151b 100644
--- a/core/modules/translation/translation.test
+++ b/core/modules/translation/translation.test
@@ -47,11 +47,7 @@ class TranslationTestCase extends DrupalWebTestCase {
     $edit = array("blocks[locale_$language_type][region]" => 'sidebar_first');
     $this->drupalPost('admin/structure/block', $edit, t('Save blocks'));
 
-    // Enable URL language detection and selection to make the language switcher
-    // block appear.
-    $edit = array('language[enabled][locale-url]' => TRUE);
-    $this->drupalPost('admin/config/regional/language/configure', $edit, t('Save settings'));
-    $this->assertRaw(t('Language negotiation configuration saved.'), t('URL language detection enabled.'));
+    // Reset static caches in our local language environment.
     $this->resetCaches();
 
     $this->drupalLogin($this->translator);
@@ -200,6 +196,7 @@ class TranslationTestCase extends DrupalWebTestCase {
     $this->drupalLogin($this->admin_user);
     $edit = array('languages[it][enabled]' => TRUE);
     $this->drupalPost('admin/config/regional/language', $edit, t('Save configuration'));
+    $this->resetCaches();
     $this->drupalLogin($this->translator);
 
     // Create a Basic page in English.
@@ -258,7 +255,9 @@ class TranslationTestCase extends DrupalWebTestCase {
    * Reset static caches to make the test code match the client site behavior.
    */
   function resetCaches() {
+    drupal_static_reset('language_list');
     drupal_static_reset('locale_url_outbound_alter');
+    drupal_static_reset('locale_language_url_rewrite_url');
   }
 
   /**