diff --git a/core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php b/core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php
index 82c3c8f..999dd82 100644
--- a/core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php
+++ b/core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php
@@ -228,7 +228,9 @@ public function updateConfigTranslation($name, $langcodes = array()) {
     $wrapper = $this->getLocaleWrapper($name);
     $count = 0;
     foreach ($langcodes as $langcode) {
-      $translation = $wrapper ? $wrapper->getTranslation($langcode) : NULL;
+      $existing = $this->getTranslationData($name, $langcode);
+      $existing = $existing ?: array();
+      $translation = $wrapper ? $wrapper->getTranslation($langcode, $existing) : NULL;
       if ($translation) {
         $this->configStorage->writeTranslation($name, $langcode, $translation);
         $count++;
diff --git a/core/modules/locale/lib/Drupal/locale/LocaleTypedConfig.php b/core/modules/locale/lib/Drupal/locale/LocaleTypedConfig.php
index a4d1692..141de9f 100644
--- a/core/modules/locale/lib/Drupal/locale/LocaleTypedConfig.php
+++ b/core/modules/locale/lib/Drupal/locale/LocaleTypedConfig.php
@@ -35,10 +35,6 @@ class LocaleTypedConfig extends Element {
   /**
    * Constructs a configuration wrapper object.
    *
-   * @param array $definition
-   *   The data definition.
-   * @param string $name
-   *   The configuration object name.
    * @param Drupal\Core\Config\Schema\Element $element
    *   Typed configuration element.
    * @param Drupal\Core\StringTranslation\Translator\TranslatorInterface $translator;
@@ -65,11 +61,15 @@ public function getTypedConfig() {
    *
    * @param string $langcode
    *   Language code to translate to.
+   * @param array $defaults
+   *   Optional existing translations to be used when translatability is not
+   *   defined. These may be provided by other modules and we just keep them
+   *   in case we cannot determine how to translate an element.
    * @return array
    *   Translated configuration data.
    */
-  public function getTranslation($langcode) {
-    return $this->getElementTranslation($this->getTypedConfig(), $langcode);
+  public function getTranslation($langcode, $defaults = array()) {
+    return $this->getElementTranslation($this->getTypedConfig(), $langcode, $defaults);
   }
 
   /**
@@ -85,12 +85,12 @@ public function getTranslation($langcode) {
    *   Configuration data translated to the requested language if available,
    *   an empty array otherwise.
    */
-  protected function getElementTranslation($element, $langcode) {
+  protected function getElementTranslation($element, $langcode, $defaults) {
     $translation = array();
     if ($element instanceof ArrayElement) {
-      $translation = $this->getArrayTranslation($element, $langcode);
+      $translation = $this->getArrayTranslation($element, $langcode, $defaults);
     }
-    elseif ($this->translateElement($element, $langcode)) {
+    elseif ($this->translateElement($element, $langcode, $defaults)) {
       $translation = $element->getValue();
     }
     return $translation;
@@ -103,14 +103,17 @@ protected function getElementTranslation($element, $langcode) {
    *   Typed configuration array element.
    * @param string $langcode
    *   Language code to translate to.
+   * @param array|NULL $defaults
+   *   Existing translations.
    *
    * @return array
    *   Configuration data translated to the requested language.
    */
-  protected function getArrayTranslation(ArrayElement $element, $langcode) {
+  protected function getArrayTranslation(ArrayElement $element, $langcode, $defaults) {
     $translation = array();
     foreach ($element as $key => $property) {
-      $value = $this->getElementTranslation($property, $langcode);
+      $default = $defaults && isset($defaults[$key]) ? $defaults[$key] : NULL;
+      $value = $this->getElementTranslation($property, $langcode, $default);
       if (!empty($value)) {
         $translation[$key] = $value;
       }
@@ -132,17 +135,27 @@ protected function getArrayTranslation(ArrayElement $element, $langcode) {
    *   Configuration element.
    * @param string $langcode
    *   Language code to translate to.
+   * @param $default
+   *   Current translation for this element that will be kept when the element
+   *   cannot be translated through localization.
    *
    * @return bool
    *   Whether the element fits the translation criteria.
    */
-  protected function translateElement(\Drupal\Core\TypedData\TypedDataInterface $element, $langcode) {
+  protected function translateElement(\Drupal\Core\TypedData\TypedDataInterface $element, $langcode, $default) {
     $definition = $element->getDefinition();
     $value = $element->getValue();
-    if ($value && !empty($definition['translatable'])) {
-      $context = isset($definition['locale context']) ? $definition['locale context'] : '';
-      if ($translation = $this->translator->getStringTranslation($langcode, $value, $context)) {
-        $element->setValue($translation);
+    if (isset($value)) {
+      if ($value && !empty($definition['translatable'])) {
+        $context = isset($definition['locale context']) ? $definition['locale context'] : '';
+        if ($translation = $this->translator->getStringTranslation($langcode, $value, $context)) {
+          $element->setValue($translation);
+          return TRUE;
+        }
+      }
+      elseif (!isset($definition['translatable']) && isset($default)) {
+        // Translatability is undefined but we have a default translation.
+        $element->setValue($default);
         return TRUE;
       }
     }
diff --git a/core/modules/locale/lib/Drupal/locale/Tests/LocaleConfigTranslationTest.php b/core/modules/locale/lib/Drupal/locale/Tests/LocaleConfigTranslationTest.php
index 18f3d97..966dd8b 100644
--- a/core/modules/locale/lib/Drupal/locale/Tests/LocaleConfigTranslationTest.php
+++ b/core/modules/locale/lib/Drupal/locale/Tests/LocaleConfigTranslationTest.php
@@ -194,9 +194,15 @@ function testConfigUpdate() {
     $this->drupalGet($langcode);
     $this->assertText($site_name, 'The translated site name is displayed after configuration is changed back to default.');
 
-    // Check translated configuration is deleted after language is deleted.
-    $config_name = 'locale.config.' . $langcode . '.system.site';
+    // Check whether translations provided by other modules are kept.
     $config_factory = $this->container->get('config.factory');
+    $config_name = 'locale.config.' . $langcode . '.system.site';
+    $config_factory->get($config_name)->set('page.front', 'admin')->save();
+    $edit = array();
+    $this->drupalPost('admin/config/system/site-information', $edit, t('Save configuration'));
+    $this->assertEqual($config_factory->get($config_name)->get('page.front'), 'admin', 'Other translated elements are kept after refreshing translation.');
+
+    // Check translated configuration is deleted after language is deleted.
     $this->assertEqual($config_factory->get($config_name)->get('name'), $site_name, 'Translated site name is stored into configuration.');
     $edit = array(
       'confirm' => 1,