diff --git a/core/modules/datetime/datetime.install b/core/modules/datetime/datetime.install
new file mode 100644
index 0000000..856f3a6
--- /dev/null
+++ b/core/modules/datetime/datetime.install
@@ -0,0 +1,103 @@
+<?php
+
+/**
+ * @file
+ * Update hooks for the Datetime module.
+ */
+
+use Drupal\Core\Database\Database;
+use Drupal\Core\Entity\Schema\DynamicallyFieldableEntityStorageSchemaInterface;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
+use Drupal\field\Entity\FieldStorageConfig;
+
+/**
+ * Add the 'timezone' field to all datetime field tables.
+ */
+function datetime_update_8001(array &$sandbox) {
+
+  if (!isset($sandbox['progress'])) {
+    $sandbox['progress'] = 0;
+    $sandbox['current_id'] = '';
+    $sandbox['processed'] = [];
+
+    // Find all required updates.
+    $change_list = [];
+    foreach (\Drupal::entityTypeManager()->getDefinitions() as $entity_type_id => $entity_type) {
+      $storage = \Drupal::entityTypeManager()->getStorage($entity_type_id);
+      if ($storage instanceof DynamicallyFieldableEntityStorageSchemaInterface) {
+        $field_changes = [];
+        $field_storage_definitions = \Drupal::service('entity_field.manager')->getFieldStorageDefinitions($entity_type_id);
+        $original_storage_definitions = \Drupal::service('entity.last_installed_schema.repository')->getLastInstalledFieldStorageDefinitions($entity_type_id);
+        foreach (array_intersect_key($field_storage_definitions, $original_storage_definitions) as $field_name => $storage_definition) {
+          if ($storage_definition->getType() === 'datetime' && $storage->requiresFieldStorageSchemaChanges($storage_definition, $original_storage_definitions[$field_name])) {
+            /** @var \Drupal\Core\Entity\Sql\DefaultTableMapping $table_mapping */
+            $table_mapping = $storage->getTableMapping();
+            $field_changes[$field_name] = $table_mapping->getFieldTableName($field_name);
+          }
+        }
+
+        if (!empty($field_changes)) {
+
+
+          $change_list[$entity_type_id] = [
+            'field_storage_definitions' => $field_changes,
+            'revision_table' => $entity_type->getRevisionTable(),
+          ];
+        }
+      }
+    }
+
+    $sandbox['change_list'] = $change_list;
+    $sandbox['max'] = count($change_list);
+  }
+
+  $remaining = array_diff(array_keys($sandbox['change_list']), $sandbox['processed']);
+  if (!empty($remaining)) {
+    $entity_type_id = array_pop($remaining);
+    $field_changes = $sandbox['change_list'][$entity_type_id];
+
+    $field_spec = [
+      'description' => 'The date timezone.',
+      'type' => 'varchar',
+      'length' => 50,
+    ];
+    $schema = Database::getConnection()->schema();
+
+    foreach ($field_changes['field_storage_definitions'] as $field_name => $field_table) {
+      $timezone_field_name = $field_name . '_timezone';
+      $field_schema = [
+        'fields' => [
+          // Include the 'value' field in order to properly create the index.
+          $field_name . '_value' => [
+            'description' => 'The date value.',
+            'type' => 'varchar',
+            'length' => 20,
+          ],
+          $timezone_field_name => $field_spec,
+        ],
+        'indexes' => [
+          'value_timezone' => [$field_name . '_value', $timezone_field_name],
+        ],
+      ];
+      $base_table = $field_changes['base_table'] . '__' . $field_name;
+      $schema->addField($field_table, $timezone_field_name, $field_spec);
+      $schema->addIndex($field_table, 'value_timezone', $field_schema['indexes']['value_timezone'], $field_schema);
+
+      if ($field_changes['revision_table']) {
+        $revision_table = $field_changes['revision_table'] . '__' . $field_name;
+        $schema->addField($revision_table, $timezone_field_name, $field_spec);
+        $schema->addIndex($revision_table, 'value_timezone', $field_schema['indexes']['value_timezone'], $field_schema);
+      }
+
+      // Set timezone handling to 'user', which is the behavior prior to the
+      // introduction of configurable timezone handling.
+      $field_storage = FieldStorageConfig::load($entity_type_id . '.' . $field_name);
+      $field_storage->setSetting('timezone_handling', DateTimeItem::TIMEZONE_USER);
+      \Drupal::entityDefinitionUpdateManager()
+        ->updateFieldStorageDefinition($field_storage);
+    }
+    $sandbox['processed'][] = $entity_type_id;
+  }
+
+  $sandbox['#finished'] = empty($remaining);
+}