diff --git a/core/modules/locale/src/LocaleConfigManager.php b/core/modules/locale/src/LocaleConfigManager.php
index cc833c5..9f87a5f 100644
--- a/core/modules/locale/src/LocaleConfigManager.php
+++ b/core/modules/locale/src/LocaleConfigManager.php
@@ -563,15 +563,17 @@ public function updateConfigTranslations(array $names, array $langcodes = array(
       foreach ($langcodes as $langcode) {
         $processed = $this->processTranslatableData($name, $active, $translatable, $langcode);
         if ($langcode != $active_langcode) {
+          $override = $this->languageManager->getLanguageConfigOverride($langcode, $name);
           // If the language code is not the same as the active storage
           // language, we should update a configuration override.
           if (!empty($processed)) {
+            $data = NestedArray::mergeDeepArray(array($override->get(), $processed), TRUE);
             // Update translation data in configuration override.
-            $this->saveTranslationOverride($name, $langcode, $processed);
+            $this->saveTranslationOverride($name, $langcode, $data);
             $count++;
           }
           else {
-            $override = $this->languageManager->getLanguageConfigOverride($langcode, $name);
+
             if (!$override->isNew()) {
               $data = $this->filterOverride($override->get(), $translatable);
               if (empty($data)) {
diff --git a/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php b/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
index 4a5c154..66daa2c 100644
--- a/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
+++ b/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
@@ -99,6 +99,16 @@ public function testConfigTranslationModuleInstall() {
     $this->drupalGet('af');
     $this->assertText('Test site slogan in Afrikaans');
 
+    $override = \Drupal::languageManager()->getLanguageConfigOverride('af', 'locale_test_translate.settings');
+    $this->assertEqual('Locale can translate Afrikaans', $override->get('translatable_default_with_translation'));
+
+    // Update test configuration.
+    $override
+      ->set('translatable_no_default', 'This translation is preserved')
+      ->set('translatable_default_with_translation', 'This translation is preserved')
+      ->set('translatable_default_with_no_translation', 'This translation is preserved')
+      ->save();
+
     // Install any module.
     $this->drupalPostForm('admin/modules', ['modules[Core][dblog][enable]' => 'dblog'], t('Install'));
     $this->assertText('Module Database Logging has been enabled.');
@@ -107,6 +117,15 @@ public function testConfigTranslationModuleInstall() {
     // appears.
     $this->drupalGet('af');
     $this->assertText('Test site slogan in Afrikaans');
+
+    $this->rebuildContainer();
+    $override = \Drupal::languageManager()->getLanguageConfigOverride('af', 'locale_test_translate.settings');
+    $expected = [
+      'translatable_no_default' => 'This translation is preserved',
+      'translatable_default_with_translation' => 'This translation is preserved',
+      'translatable_default_with_no_translation' => 'This translation is preserved'
+    ];
+    $this->assertEqual($expected, $override->get());
   }
 
 }
diff --git a/core/modules/locale/tests/modules/locale_test_translate/config/install/locale_test_translate.settings.yml b/core/modules/locale/tests/modules/locale_test_translate/config/install/locale_test_translate.settings.yml
new file mode 100644
index 0000000..544dad7
--- /dev/null
+++ b/core/modules/locale/tests/modules/locale_test_translate/config/install/locale_test_translate.settings.yml
@@ -0,0 +1,3 @@
+translatable_no_default: ''
+translatable_default_with_translation: 'Locale can translate'
+translatable_default_with_no_translation: 'Locale can not translate'
diff --git a/core/modules/locale/tests/modules/locale_test_translate/config/schema/locale_test_translate.schema.yml b/core/modules/locale/tests/modules/locale_test_translate/config/schema/locale_test_translate.schema.yml
new file mode 100644
index 0000000..93e57c6
--- /dev/null
+++ b/core/modules/locale/tests/modules/locale_test_translate/config/schema/locale_test_translate.schema.yml
@@ -0,0 +1,10 @@
+locale_test_translate.settings:
+  type: config_object
+  label: 'Test for locale translations'
+  mapping:
+    translatable_no_default:
+      type: label
+    translatable_default_with_translation:
+      type: label
+    translatable_default_with_no_translation:
+      type: label
diff --git a/core/modules/locale/tests/test.af.po b/core/modules/locale/tests/test.af.po
index 2391464..812eca9 100644
--- a/core/modules/locale/tests/test.af.po
+++ b/core/modules/locale/tests/test.af.po
@@ -8,3 +8,6 @@ msgstr ""
 
 msgid "@site is currently under maintenance. We should be back shortly. Thank you for your patience."
 msgstr "Ons is tans besig met onderhoud op @site. Wees asseblief geduldig, ons sal binnekort weer terug wees."
+
+msgid "Locale can translate"
+msgstr "Locale can translate Afrikaans"