diff --git a/core/modules/locale/src/LocaleConfigManager.php b/core/modules/locale/src/LocaleConfigManager.php
index 1328873..9f87a5f 100644
--- a/core/modules/locale/src/LocaleConfigManager.php
+++ b/core/modules/locale/src/LocaleConfigManager.php
@@ -167,13 +167,16 @@ protected function getTranslatableData(TypedDataInterface $element) {
       }
     }
     else {
+      // Something is only translatable by Locale if there is a string in the
+      // first place.
+      $value = $element->getValue();
       $definition = $element->getDataDefinition();
-      if (!empty($definition['translatable'])) {
+      if (!empty($definition['translatable']) && $value !== '' && $value !== NULL) {
         $options = array();
         if (isset($definition['translation context'])) {
           $options['context'] = $definition['translation context'];
         }
-        return new TranslatableMarkup($element->getValue(), array(), $options);
+        return new TranslatableMarkup($value, array(), $options);
       }
     }
     return $translatable;
@@ -560,15 +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 75966b8..66daa2c 100644
--- a/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
+++ b/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
@@ -26,19 +26,11 @@ class LocaleConfigTranslationImportTest extends WebTestBase {
   public static $modules = array('language', 'locale_test_translate');
 
   /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    parent::setUp();
-
-    $admin_user = $this->drupalCreateUser(array('administer modules', 'administer site configuration', 'administer languages', 'access administration pages', 'administer permissions'));
-    $this->drupalLogin($admin_user);
-  }
-
-  /**
    * Test update changes configuration translations if enabled after language.
    */
   public function testConfigTranslationImport() {
+    $admin_user = $this->drupalCreateUser(array('administer modules', 'administer site configuration', 'administer languages', 'access administration pages', 'administer permissions'));
+    $this->drupalLogin($admin_user);
 
     // Add a language. The Afrikaans translation file of locale_test_translate
     // (test.af.po) has been prepared with a configuration translation.
@@ -77,4 +69,63 @@ public function testConfigTranslationImport() {
     $this->assertEqual($override->get('message'), 'Ons is tans besig met onderhoud op @site. Wees asseblief geduldig, ons sal binnekort weer terug wees.');
   }
 
+  /**
+   * Test update changes configuration translations if enabled after language.
+   */
+  public function testConfigTranslationModuleInstall() {
+
+    // Enable locale, block and config_translation modules.
+    $this->container->get('module_installer')->install(['block', 'config_translation']);
+    $this->resetAll();
+
+    $admin_user = $this->drupalCreateUser(array('administer modules', 'administer site configuration', 'administer languages', 'access administration pages', 'administer permissions', 'translate configuration'));
+    $this->drupalLogin($admin_user);
+
+    // Enable import of translations. By default this is disabled for automated
+    // tests.
+    $this->config('locale.settings')
+      ->set('translation.import_enabled', TRUE)
+      ->save();
+
+    // Add predefined language.
+    $this->drupalPostForm('admin/config/regional/language/add', ['predefined_langcode' => 'af'], t('Add language'));
+
+    // Add the system branding block to the page.
+    $this->drupalPlaceBlock('system_branding_block', array('region' => 'header', 'id' => 'site-branding'));
+    $this->drupalPostForm('admin/config/system/site-information', ['site_slogan' => 'Test site slogan'], 'Save configuration');
+    $this->drupalPostForm('admin/config/system/site-information/translate/af/edit', ['translation[config_names][system.site][slogan]' => 'Test site slogan in Afrikaans'], 'Save translation');
+
+    // Get the front page and ensure that the translated configuration appears.
+    $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.');
+
+    // Get the front page and ensure that the translated configuration still
+    // 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"