diff --git a/core/modules/datetime/config/schema/datetime.schema.yml b/core/modules/datetime/config/schema/datetime.schema.yml
index 1d8f595..ef81fbf 100644
--- a/core/modules/datetime/config/schema/datetime.schema.yml
+++ b/core/modules/datetime/config/schema/datetime.schema.yml
@@ -22,6 +22,8 @@ field.datetime.value:
       label: 'Default value'
       sequence:
         - type: string
+          label: 'Type'
+        - type: string
           label: 'Value'
 
 entity_view_display.field.datetime_default:
diff --git a/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeFieldItemList.php b/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeFieldItemList.php
index 5cd1c24..5963db0 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeFieldItemList.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeFieldItemList.php
@@ -24,6 +24,11 @@ class DateTimeFieldItemList extends FieldItemList {
   const DEFAULT_VALUE_NOW = 'now';
 
   /**
+   * Defines the default value as relative.
+   */
+  const DEFAULT_VALUE_CUSTOM = 'relative';
+
+  /**
    * {@inheritdoc}
    */
   public function defaultValuesForm(array &$form, FormStateInterface $form_state) {
@@ -32,13 +37,27 @@ public function defaultValuesForm(array &$form, FormStateInterface $form_state)
 
       $element = array(
         '#parents' => array('default_value_input'),
-        'default_date' => array(
+        'default_date_type' => array(
           '#type' => 'select',
           '#title' => t('Default date'),
           '#description' => t('Set a default value for this date.'),
-          '#default_value' => isset($default_value[0]['default_date']) ? $default_value[0]['default_date'] : '',
-          '#options' => array(static::DEFAULT_VALUE_NOW => t('The current date')),
+          '#default_value' => isset($default_value[0]['default_date_type']) ? $default_value[0]['default_date_type'] : '',
+          '#options' => array(
+            static::DEFAULT_VALUE_NOW => t('Current date'),
+            static::DEFAULT_VALUE_CUSTOM => t('Relative date'),
+          ),
           '#empty_value' => '',
+        ),
+        'default_date' => array(
+          '#type' => 'textfield',
+          '#title' => t('Relative default value'),
+          '#description' => t("Describe a time by reference to the current day, like '+90 days' (90 days from the day the field is created) or '+1 Saturday' (the next Saturday). See !strtotime for more details.", array('!strtotime' => l('strtotime', 'http://www.php.net/manual/en/function.strtotime.php'))),
+          '#default_value' => (isset($default_value[0]['default_date_type']) && $default_value[0]['default_date_type'] == static::DEFAULT_VALUE_CUSTOM) ? $default_value[0]['default_date'] : '',
+          '#states' => array(
+            'visible' => array(
+              ':input[id="edit-default-value-input-default-date-type"]' => array('value' => static::DEFAULT_VALUE_CUSTOM),
+            )
+          )
         )
       );
 
@@ -49,13 +68,23 @@ public function defaultValuesForm(array &$form, FormStateInterface $form_state)
   /**
    * {@inheritdoc}
    */
-  public function defaultValuesFormValidate(array $element, array &$form, FormStateInterface $form_state) { }
+  public function defaultValuesFormValidate(array $element, array &$form, FormStateInterface $form_state) {
+    if ($form_state['values']['default_value_input']['default_date_type'] == static::DEFAULT_VALUE_CUSTOM) {
+      $is_strtotime = @strtotime($form_state->getValue(array('default_value_input', 'default_date')));
+      if (!$is_strtotime) {
+        $form_state->setErrorByName('default_value_input][default_date', t('The relative date value entered is invalid.'));
+      }
+    }
+  }
 
   /**
    * {@inheritdoc}
    */
   public function defaultValuesFormSubmit(array $element, array &$form, FormStateInterface $form_state) {
-    if ($form_state->getValue(array('default_value_input', 'default_date'))) {
+    if ($form_state->getValue(array('default_value_input', 'default_date_type'))) {
+      if ($form_state->getValue(array('default_value_input', 'default_date_type')) == static::DEFAULT_VALUE_NOW) {
+        $form_state->setValueForElement($element['default_date'], static::DEFAULT_VALUE_NOW);
+      }
       return array($form_state->getValue('default_value_input'));
     }
     return array();
@@ -67,10 +96,10 @@ public function defaultValuesFormSubmit(array $element, array &$form, FormStateI
   public static function processDefaultValue($default_value, ContentEntityInterface $entity, FieldDefinitionInterface $definition) {
     $default_value = parent::processDefaultValue($default_value, $entity, $definition);
 
-    if (isset($default_value[0]['default_date']) && $default_value[0]['default_date'] == static::DEFAULT_VALUE_NOW) {
+    if (isset($default_value[0]['default_date_type'])) {
       // A default value should be in the format and timezone used for date
       // storage.
-      $date = new DrupalDateTime('now', DATETIME_STORAGE_TIMEZONE);
+      $date = new DrupalDateTime($default_value[0]['default_date'], DATETIME_STORAGE_TIMEZONE);
       $storage_format = $definition->getSetting('datetime_type') == DateTimeItem::DATETIME_TYPE_DATE ? DATETIME_DATE_STORAGE_FORMAT: DATETIME_DATETIME_STORAGE_FORMAT;
       $value = $date->format($storage_format);
       // We only provide a default value for the first item, as do all fields.
diff --git a/core/modules/datetime/src/Tests/DateTimeFieldTest.php b/core/modules/datetime/src/Tests/DateTimeFieldTest.php
index eefd3c3..b36777c 100644
--- a/core/modules/datetime/src/Tests/DateTimeFieldTest.php
+++ b/core/modules/datetime/src/Tests/DateTimeFieldTest.php
@@ -305,17 +305,18 @@ function testDefaultValue() {
 
     // Set now as default_value.
     $instance_edit = array(
-      'default_value_input[default_date]' => 'now',
+      'default_value_input[default_date_type]' => 'now',
     );
     $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name, $instance_edit, t('Save settings'));
 
     // Check that default value is selected in default value form.
     $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name);
-    $this->assertRaw('<option value="now" selected="selected">The current date</option>', 'The default value is selected in instance settings page');
+    $this->assertOptionSelected('edit-default-value-input-default-date-type', 'now', 'The default value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_date]', '', 'The relative default value is empty in instance settings page');
 
     // Check if default_date has been stored successfully.
     $config_entity = $this->container->get('config.factory')->get('field.instance.node.date_content.' . $field_storage->name)->get();
-    $this->assertEqual($config_entity['default_value'][0]['default_date'], 'now', 'Default value has been stored successfully');
+    $this->assertEqual($config_entity['default_value'][0], array('default_date_type' => 'now', 'default_date' => 'now'), 'Default value has been stored successfully');
 
     // Clear field cache in order to avoid stale cache values.
     \Drupal::entityManager()->clearCachedFieldDefinitions();
@@ -325,15 +326,49 @@ function testDefaultValue() {
     $expected_date = new DrupalDateTime('now', DATETIME_STORAGE_TIMEZONE);
     $this->assertEqual($new_node->get($field_storage->name)->offsetGet(0)->value, $expected_date->format(DATETIME_DATE_STORAGE_FORMAT));
 
+    // Set an invalid relative default_value to test validation.
+    $instance_edit = array(
+      'default_value_input[default_date_type]' => 'relative',
+      'default_value_input[default_date]' => 'invalid date',
+    );
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name, $instance_edit, t('Save settings'));
+
+    $this->assertText('The relative date value entered is invalid.');
+
+    // Set a relative default_value.
+    $instance_edit = array(
+      'default_value_input[default_date_type]' => 'relative',
+      'default_value_input[default_date]' => '+90 days',
+    );
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name, $instance_edit, t('Save settings'));
+
+    // Check that default value is selected in default value form.
+    $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name);
+    $this->assertOptionSelected('edit-default-value-input-default-date-type', 'relative', 'The default value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_date]', '+90 days', 'The relative default value is displayed in instance settings page');
+
+    // Check if default_date has been stored successfully.
+    $config_entity = $this->container->get('config.factory')->get('field.instance.node.date_content.' . $field_storage->name)->get();
+    $this->assertEqual($config_entity['default_value'][0], array('default_date_type' => 'relative', 'default_date' => '+90 days'), 'Default value has been stored successfully');
+
+    // Clear field cache in order to avoid stale cache values.
+    \Drupal::entityManager()->clearCachedFieldDefinitions();
+
+    // Create a new node to check that datetime field default value is +90 days.
+    $new_node = entity_create('node', array('type' => 'date_content'));
+    $expected_date = new DrupalDateTime('+90 days', DATETIME_STORAGE_TIMEZONE);
+    $this->assertEqual($new_node->get($field_storage->name)->offsetGet(0)->value, $expected_date->format(DATETIME_DATE_STORAGE_FORMAT));
+
     // Remove default value.
     $instance_edit = array(
-      'default_value_input[default_date]' => '',
+      'default_value_input[default_date_type]' => '',
     );
     $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name, $instance_edit, t('Save settings'));
 
     // Check that default value is selected in default value form.
     $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_storage->name);
-    $this->assertRaw('<option value="" selected="selected">' . t('- None -') . '</option>', 'The default value is selected in instance settings page');
+    $this->assertOptionSelected('edit-default-value-input-default-date-type', '', 'The default value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_date]', '', 'The relative default value is empty in instance settings page');
 
     // Check if default_date has been stored successfully.
     $config_entity = $this->container->get('config.factory')->get('field.instance.node.date_content.' . $field_storage->name)->get();
@@ -342,7 +377,7 @@ function testDefaultValue() {
     // Clear field cache in order to avoid stale cache values.
     \Drupal::entityManager()->clearCachedFieldDefinitions();
 
-    // Create a new node to check that datetime field default value is today.
+    // Create a new node to check that datetime field default value is not set.
     $new_node = entity_create('node', array('type' => 'date_content'));
     $this->assertNull($new_node->get($field_storage->name)->offsetGet(0)->value, 'Default value is not set');
   }