diff -u b/core/lib/Drupal/Core/Field/FieldStorageDefinitionInterface.php b/core/lib/Drupal/Core/Field/FieldStorageDefinitionInterface.php
--- b/core/lib/Drupal/Core/Field/FieldStorageDefinitionInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldStorageDefinitionInterface.php
@@ -85,10 +85,10 @@
   public function isTranslatable();
 
   /**
-   * Sets whether the field is supports translation.
+   * Sets whether the field supports translation.
    *
    * @param bool $translatable
-   *   Whether the field is supports translation.
+   *   Whether the field supports translation.
    *
    * @return $this
    */
diff -u b/core/modules/content_translation/content_translation.admin.inc b/core/modules/content_translation/content_translation.admin.inc
--- b/core/modules/content_translation/content_translation.admin.inc
+++ b/core/modules/content_translation/content_translation.admin.inc
@@ -314,12 +314,17 @@
           // If we have a storable field definition we directly persist any
           // change to translatability, otherwise we store changes in our config
           // so we can properly alter field definitions later.
+          // @todo Remove this special casing when any field definition can have
+          //   a configurable bundle override. See
+          //   https://drupal.org/node/2224761.
           $definition = $definitions[$field_name];
           if ($definition instanceof FieldInstanceConfigInterface) {
             if ($definition->isTranslatable() != $translatable) {
               $definition->setTranslatable($translatable);
               $definition->save();
             }
+            // Do not save configurable fields unnecessarily.
+            unset($bundle_settings['fields'][$field_name]);
           }
           else {
             $bundle_settings['fields'][$field_name] = $translatable;
diff -u b/core/modules/content_translation/content_translation.module b/core/modules/content_translation/content_translation.module
--- b/core/modules/content_translation/content_translation.module
+++ b/core/modules/content_translation/content_translation.module
@@ -147,14 +147,10 @@
 function content_translation_entity_bundle_field_info_alter(&$fields, EntityTypeInterface $entity_type, $bundle) {
   $settings = content_translation_get_config($entity_type->id(), $bundle, 'fields');
   if (!empty($settings)) {
-    $base_field_definitions = \Drupal::entityManager()->getBaseFieldDefinitions($entity_type->id());
     foreach ($settings as $name => $translatable) {
       // Skip storable field definitions as those are supposed to have already
       // been changed.
-      if (isset($base_field_definitions[$name]) && !$base_field_definitions[$name] instanceof FieldInstanceConfigInterface) {
-        if (!isset($fields[$name])) {
-          $fields[$name] = clone $base_field_definitions[$name];
-        }
+      if (isset($fields[$name]) && !$fields[$name] instanceof FieldInstanceConfigInterface) {
         $fields[$name]->setTranslatable((bool) $translatable);
       }
     }
diff -u b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
--- b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
+++ b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
@@ -100,7 +100,7 @@
     $this->assertTrue($definition->isTranslatable(), 'Article comment body is translatable.');
     $definition = $this->entityManager()->getFieldDefinitions('comment', 'comment')['comment_body'];
     $this->assertFalse($definition->isTranslatable(), 'Page comment body is not translatable.');
-
+    $this->assertNull(content_translation_get_config('comment', 'comment_article', 'fields'), 'Configurable fields are not saved to content_translation.settings.');
     // Test that translation can be enabled for base fields.
     $edit = array(
       'entity_types[entity_test_mul]' => TRUE,
@@ -108,6 +108,7 @@
       'settings[entity_test_mul][entity_test_mul][fields][name]' => TRUE,
     );
     $this->assertSettings('entity_test_mul', 'entity_test_mul', TRUE, $edit);
+    $this->assertNotNull(content_translation_get_config('entity_test_mul', 'entity_test_mul', 'fields'), 'Base fields are saved to content_translation.settings.');
 
     // Test that language settings are correctly stored.
     $language_configuration = language_get_default_configuration('comment', 'comment_article');
reverted:
--- b/core/modules/field/tests/modules/field_test_config/config/install/field.field.entity_test.field_test_import.yml
+++ a/core/modules/field/tests/modules/field_test_config/config/install/field.field.entity_test.field_test_import.yml
@@ -8,6 +8,7 @@
 module: text
 locked: false
 cardinality: 1
+translatable: false
 indexes:
   format:
     - format
reverted:
--- b/core/modules/field/tests/modules/field_test_config/config/install/field.field.entity_test.field_test_import_2.yml
+++ a/core/modules/field/tests/modules/field_test_config/config/install/field.field.entity_test.field_test_import_2.yml
@@ -8,6 +8,7 @@
 module: text
 locked: false
 cardinality: 1
+translatable: false
 indexes:
   format:
     - format
diff -u b/core/modules/file/src/Tests/FileFieldDisplayTest.php b/core/modules/file/src/Tests/FileFieldDisplayTest.php
--- b/core/modules/file/src/Tests/FileFieldDisplayTest.php
+++ b/core/modules/file/src/Tests/FileFieldDisplayTest.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\file\Tests;
+
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 
 /**
reverted:
--- b/core/modules/forum/config/install/field.field.taxonomy_term.forum_container.yml
+++ a/core/modules/forum/config/install/field.field.taxonomy_term.forum_container.yml
@@ -12,6 +12,7 @@
 entity_type: taxonomy_term
 locked: true
 cardinality: 1
+translatable: false
 indexes: {  }
 dependencies:
   module:
diff -u b/core/modules/system/src/Tests/Ajax/MultiFormTest.php b/core/modules/system/src/Tests/Ajax/MultiFormTest.php
--- b/core/modules/system/src/Tests/Ajax/MultiFormTest.php
+++ b/core/modules/system/src/Tests/Ajax/MultiFormTest.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\system\Tests\Ajax;
+
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 
 /**
diff -u b/core/modules/user/src/Entity/User.php b/core/modules/user/src/Entity/User.php
--- b/core/modules/user/src/Entity/User.php
+++ b/core/modules/user/src/Entity/User.php
@@ -12,7 +12,6 @@
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Field\FieldDefinition;
-use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\user\UserInterface;
 
 /**
@@ -530,7 +529,7 @@
     $fields['roles'] = FieldDefinition::create('string')
       ->setCustomStorage(TRUE)
       ->setLabel(t('Roles'))
-      ->setCardinality(FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED)
+      ->setCardinality(FieldDefinition::CARDINALITY_UNLIMITED)
       ->setDescription(t('The roles the user has.'));
 
     return $fields;
reverted:
--- b/core/profiles/standard/config/install/field.field.node.field_image.yml
+++ a/core/profiles/standard/config/install/field.field.node.field_image.yml
@@ -13,6 +13,7 @@
     height: null
 locked: false
 cardinality: 1
+translatable: false
 indexes:
   target_id:
     - target_id
reverted:
--- b/core/profiles/standard/config/install/field.field.node.field_tags.yml
+++ a/core/profiles/standard/config/install/field.field.node.field_tags.yml
@@ -10,6 +10,7 @@
       parent: 0
 locked: false
 cardinality: -1
+translatable: false
 indexes:
   target_id:
     - target_id
reverted:
--- b/core/profiles/standard/config/install/field.field.user.user_picture.yml
+++ a/core/profiles/standard/config/install/field.field.user.user_picture.yml
@@ -15,6 +15,7 @@
 module: image
 locked: false
 cardinality: 1
+translatable: false
 indexes:
   target_id:
     - target_id