diff --git a/core/modules/image/image.install b/core/modules/image/image.install
index c3505e9..5cdf997 100644
--- a/core/modules/image/image.install
+++ b/core/modules/image/image.install
@@ -104,100 +104,67 @@ function image_requirements($phase) {
   return $requirements;
 }
 
-/*
- * Load all the effects for an image style.
+/**
+ * Loads all effects for an image style.
  *
- * Helper function for retrieving image effects from the image_effects database
- * table for a given image style. This is a combination of the
- * image_style_effects() and image_effects() functions from Drupal 7.
+ * @param array $style
+ *   The image style (array) to retrieve effects for.
  *
  * @see image_update_8000()
  */
-function _image_upgrade_style_effects($style) {
-  $effects = &drupal_static(__FUNCTION__);
-
-  if (!isset($effects)) {
-    $effects = array();
-
-    // Get image effects.
-    $result = db_select('image_effects', NULL, array('fetch' => PDO::FETCH_ASSOC))
-      ->fields('image_effects')
-      ->orderBy('image_effects.weight', 'ASC')
-      ->execute();
-    foreach ($result as $effect) {
-      $effect['data'] = unserialize($effect['data']);
-      $definition = image_effect_definition_load($effect['name']);
-      // Do not load image effects whose definition cannot be found.
-      if ($definition) {
-        $effect = array_merge($definition, $effect);
-        // Generate machine name for each effect.
-        $effect['ieid'] = $effect['name'];
-        foreach ($effect['data'] as $key => $value) {
-          $effect['ieid'] .= '_' . $value;
-        }
-        $effect['ieid'] = preg_replace('@[^a-zA-Z0-9_-]@', '', $effect['ieid']);
-        // Remove deprecated items from the effect.
-        $deprecated = array('effect callback', 'dimensions callback', 'form callback', 'summary theme', 'help', 'label', 'dimensions passthrough', 'module');
-        foreach ($effect as $key => $value) {
-          if (in_array($key, $deprecated)) {
-            unset($effect[$key]);
-          }
-        }
-        $effects[$effect['ieid']] = $effect;
-      }
+function _image_update_get_style_with_effects(array $style) {
+  // Retrieve image effects.
+  // @todo Module updates are not able to invoke module hooks and API functions;
+  //   additional information previously supplied via hook_image_effect_info()
+  //   is not and cannot be taken into account.
+  $effects = array();
+  $result = db_select('image_effects', NULL, array('fetch' => PDO::FETCH_ASSOC))
+    ->fields('image_effects')
+    ->condition('isid', $style['isid'])
+    ->execute();
+  foreach ($result as $effect) {
+    unset($effect['isid']);
+    $effect['data'] = unserialize($effect['data']);
+
+    // Generate new key for each effect.
+    $effect['ieid'] = $effect['name'];
+    foreach ($effect['data'] as $key => $value) {
+      $effect['ieid'] .= '_' . $value;
     }
-  }
+    $effect['ieid'] = preg_replace('@[^a-zA-Z0-9_-]@', '', $effect['ieid']);
 
-  $style_effects = array();
-  foreach ($effects as $effect) {
-    if ($style['isid'] == $effect['isid']) {
-      unset($effect['isid']);
-      $style_effects[$effect['ieid']] = $effect;
-    }
+    $effects[$effect['ieid']] = $effect;
   }
-
-  return $style_effects;
+  return $effects;
 }
 
 /**
  * Convert existing image styles to the new config system.
  */
 function image_update_8000() {
-  // Install default config for the image module
-  config_install_default_config('image');
-
-  // Get the image module-defined styles.
   $styles = array();
-
-  // Get the user generated styles. If there are overrides of any of
-  // the image module's default styles, then they will overwrite the
-  // default style.
-  $user_styles = db_select('image_styles', NULL, array('fetch' => PDO::FETCH_ASSOC))
+  $result = db_select('image_styles', NULL, array('fetch' => PDO::FETCH_ASSOC))
     ->fields('image_styles')
-    ->orderBy('name')
     ->execute()
     ->fetchAllAssoc('name', PDO::FETCH_ASSOC);
-
-  foreach ($user_styles as $style_name => $style) {
-    $style['effects'] = _image_upgrade_style_effects($style);
-    if (isset($styles[$style_name]['module'])) {
-      $style['module'] = $styles[$style_name]['module'];
-    }
+  foreach ($result as $style_name => $style) {
+    $style['effects'] = _image_update_get_style_with_effects($style);
     $styles[$style_name] = $style;
   }
 
-  // Convert styles to the config system
+  // Convert each style into a configuration object.
   foreach ($styles as $name => $style) {
     $config = config('image.style.' . $name);
-
     $config->set('name', $name);
-    if (isset($style['effects'])) {
-      $config->set('effects', $style['effects']);
-    }
-    else {
-      $config->set('effects', array());
-    }
-
+    $config->set('effects', $style['effects']);
     $config->save();
   }
 }
+
+/**
+ * Remove the {image_styles} and {image_effects} tables.
+ */
+function image_update_8001() {
+  db_drop_table('image_styles');
+  db_drop_table('image_effects');
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/ImageUpgradePathTest.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ImageUpgradePathTest.php
index fa9fe41..9e72305 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/ImageUpgradePathTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ImageUpgradePathTest.php
@@ -20,7 +20,6 @@ class ImageUpgradePathTest extends UpgradePathTestBase {
   }
 
   public function setUp() {
-    // Path to the database dump files.
     $this->databaseDumpFiles = array(
       drupal_get_path('module', 'system') . '/tests/upgrade/drupal-7.bare.standard_all.database.php.gz',
       drupal_get_path('module', 'system') . '/tests/upgrade/drupal-7.image.database.php',
@@ -34,49 +33,46 @@ class ImageUpgradePathTest extends UpgradePathTestBase {
   public function testImageStyleUpgrade() {
     $this->assertTrue($this->performUpgrade(), 'The upgrade was completed successfully.');
 
-    // Test that overridden and custom image styles are properly upgraded.
-    $styles = array(
-      'test-custom' => array(
-        'name' => 'test-custom',
-        'effects' => array(
-          'image_rotate_90_FFFFFF_1' => array(
-            'name' => 'image_rotate',
-            'data' => array(
-              'degrees' => '90',
-              'bgcolor' => '#FFFFFF',
-              'random' => '1',
-            ),
-            'ieid' => 'image_rotate_90_FFFFFF_1',
-            'weight' => '1',
-          ),
-          'image_desaturate' => array(
-            'name' => 'image_desaturate',
-            'data' => array(),
-            'ieid' => 'image_desaturate',
-            'weight' => '2',
+    // Verify that image styles were properly upgraded.
+    $expected_styles['test-custom'] = array(
+      'name' => 'test-custom',
+      'effects' => array(
+        'image_rotate_90_FFFFFF_1' => array(
+          'name' => 'image_rotate',
+          'data' => array(
+            'degrees' => '90',
+            'bgcolor' => '#FFFFFF',
+            'random' => '1',
           ),
+          'ieid' => 'image_rotate_90_FFFFFF_1',
+          'weight' => '1',
+        ),
+        'image_desaturate' => array(
+          'name' => 'image_desaturate',
+          'data' => array(),
+          'ieid' => 'image_desaturate',
+          'weight' => '2',
         ),
       ),
-      'thumbnail' => array(
-        'name' => 'thumbnail',
-        'effects' => array (
-          'image_scale_177_177_0' => array(
-            'name' => 'image_scale',
-            'data' => array (
-              'width' => '177',
-              'height' => '177',
-              'upscale' => '0',
-            ),
-            'ieid' => 'image_scale_177_177_0',
-            'weight' => '0',
+    );
+    $expected_styles['thumbnail'] = array(
+      'name' => 'thumbnail',
+      'effects' => array (
+        'image_scale_177_177_0' => array(
+          'name' => 'image_scale',
+          'data' => array (
+            'width' => '177',
+            'height' => '177',
+            'upscale' => '0',
           ),
+          'ieid' => 'image_scale_177_177_0',
+          'weight' => '0',
         ),
       ),
     );
-
-    foreach ($styles as $name => $style) {
+    foreach ($expected_styles as $name => $style) {
       $config = config('image.style.' . $name)->get();
-      $this->assertEqual($style, $config, t('Upgraded image style %name successfully.', array('%name' => $name)));
+      $this->assertEqual($style, $config, format_string('Expected image style %name found.', array('%name' => $name)));
     }
   }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/SystemUpgradePathTest.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/SystemUpgradePathTest.php
index cab0b7f..3643a84 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/SystemUpgradePathTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/SystemUpgradePathTest.php
@@ -8,19 +8,18 @@
 namespace Drupal\system\Tests\Upgrade;
 
 /**
- * Test upgrade of non-default values for system variables.
+ * Tests upgrade of system variables.
  */
 class SystemUpgradePathTest extends UpgradePathTestBase {
   public static function getInfo() {
     return array(
       'name' => 'System upgrade test',
-      'description' => 'Upgrade tests for non-default values of system variables.',
+      'description' => 'Tests upgrade of system variables.',
       'group' => 'Upgrade path',
     );
   }
 
   public function setUp() {
-    // Path to the database dump files.
     $this->databaseDumpFiles = array(
       drupal_get_path('module', 'system') . '/tests/upgrade/drupal-7.bare.standard_all.database.php.gz',
       drupal_get_path('module', 'system') . '/tests/upgrade/drupal-7.system.database.php',
@@ -29,26 +28,24 @@ class SystemUpgradePathTest extends UpgradePathTestBase {
   }
 
   /**
-   * Tests that custom and overridden image styles have been upgraded.
+   * Tests upgrade of system variables.
    */
   public function testSystemVariableUpgrade() {
     $this->assertTrue($this->performUpgrade(), 'The upgrade was completed successfully.');
 
-    // Test that the overridden values were properly converted.
-    $overrides = array(
-      'system.performance' => array(
-        'cache' => 1,
-        'page_cache_maximum_age' => '1800',
-        'page_compression' => 1,
-        'preprocess_css' => 1,
-        'preprocess_js' => 1,
-      ),
+    // Verify that variables were properly upgraded.
+    $expected_config['system.performance'] = array(
+      'cache' => 1,
+      'page_cache_maximum_age' => '1800',
+      'page_compression' => 1,
+      'preprocess_css' => 1,
+      'preprocess_js' => 1,
     );
-    foreach ($overrides as $file => $values) {
+    foreach ($expected_config as $file => $values) {
       $config = config($file);
       foreach ($values as $name => $value) {
         $stored = $config->get($name);
-        $this->assertEqual($value, $stored, t('Stored value %stored for %name matches old value %value.', array('%stored' => $stored, '%name' => $name, '%value' => $value)));
+        $this->assertEqual($value, $stored, format_string('Expected value for %name found: %stored (previously: %value).', array('%stored' => $stored, '%name' => $name, '%value' => $value)));
       }
     }
   }
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 797078e..cf67428 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -1998,11 +1998,11 @@ function system_update_8014() {
 }
 
 /**
- * Moves performance system settings from variable to config.
+ * Moves system performance settings from variable to config.
  *
  * @ingroup config_upgrade
  */
-function system_update_8014() {
+function system_update_8015() {
   update_variables_to_config('system.performance', array(
     'cache' => 'cache',
     'page_cache_maximum_age' => 'page_cache_maximum_age',
diff --git a/core/modules/system/tests/upgrade/drupal-7.image.database.php b/core/modules/system/tests/upgrade/drupal-7.image.database.php
index 3cc99c0..c03ecf0 100644
--- a/core/modules/system/tests/upgrade/drupal-7.image.database.php
+++ b/core/modules/system/tests/upgrade/drupal-7.image.database.php
@@ -10,6 +10,23 @@
  * altogether.
  */
 
+// Add image styles.
+db_insert('image_styles')->fields(array(
+  'isid',
+  'name',
+))
+// Override thumbnail style.
+->values(array(
+  'isid' => '1',
+  'name' => 'thumbnail',
+))
+// Custom style.
+->values(array(
+  'isid' => '2',
+  'name' => 'test-custom',
+))
+->execute();
+
 // Add image effects.
 db_insert('image_effects')->fields(array(
   'ieid',
@@ -47,20 +64,3 @@ db_insert('image_effects')->fields(array(
   'data' => 'a:0:{}',
 ))
 ->execute();
-
-// Add image styles.
-db_insert('image_styles')->fields(array(
-  'isid',
-  'name',
-))
-// Custom style.
-->values(array(
-  'isid' => '2',
-  'name' => 'test-custom',
-))
-// Override thumbnail style.
-->values(array(
-  'isid' => '1',
-  'name' => 'thumbnail',
-))
-->execute();