diff --git a/modules/promotion/src/Plugin/Commerce/PromotionOffer/BuyXGetY.php b/modules/promotion/src/Plugin/Commerce/PromotionOffer/BuyXGetY.php
index 666a64cc..a1069b45 100644
--- a/modules/promotion/src/Plugin/Commerce/PromotionOffer/BuyXGetY.php
+++ b/modules/promotion/src/Plugin/Commerce/PromotionOffer/BuyXGetY.php
@@ -103,6 +103,7 @@ class BuyXGetY extends OrderPromotionOfferBase {
       'buy_conditions' => [],
       'get_quantity' => 1,
       'get_conditions' => [],
+      'get_auto_add' => FALSE,
       'offer_type' => 'percentage',
       'offer_percentage' => '0',
       'offer_amount' => NULL,
@@ -154,6 +155,15 @@ class BuyXGetY extends OrderPromotionOfferBase {
       '#entity_types' => ['commerce_order_item'],
       '#default_value' => $this->configuration['get_conditions'],
     ];
+    $form['get']['auto_add'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t("Automatically add the offer product to the cart if it isn't in it already"),
+      '#description' => $this->t('This behavior will only work when a single product variation (or a single product with only one variation) is specified.'),
+      '#default_value' => $this->configuration['get_auto_add'],
+      '#states' => [
+        'visible' => [$this->getAutoAddStatesVisibility()],
+      ],
+    ];
 
     $parents = array_merge($form['#parents'], ['offer', 'type']);
     $selected_offer_type = NestedArray::getValue($form_state->getUserInput(), $parents);
@@ -224,6 +234,27 @@ class BuyXGetY extends OrderPromotionOfferBase {
     if ($values['offer']['type'] == 'percentage' && empty($values['offer']['percentage'])) {
       $form_state->setError($form, $this->t('Percentage must be a positive number.'));
     }
+
+    if ($values['get']['auto_add']) {
+      // Ensure that at least one compatible condition enabled.
+      $valid_condition_ids = array_keys(array_filter($this->conditionManager->getFilteredDefinitions('commerce_promotion', ['commerce_order_item']), function ($definition) {
+        return is_subclass_of($definition['class'], PurchasableEntityConditionInterface::class);
+      }));
+      $has_valid_condition = FALSE;
+      foreach ($values['get']['conditions']['products'] as $condition_id => $condition_values) {
+        if (isset($valid_condition_ids[$condition_id]) && $condition_values['enable'] == 1) {
+          $has_valid_condition = TRUE;
+        }
+      }
+      if (!$has_valid_condition) {
+        $form_state->setError($form['get'], $this->t('The "auto-add" offer can only be enabled when a compatible "get" condition is used.'));
+      }
+
+      // Ensure that the offer is a 100% discount.
+      if ($values['offer']['type'] == 'fixed_amount' || ($values['offer']['type'] == 'percentage' && $values['offer']['percentage'] != '100')) {
+        $form_state->setError($form['offer'], $this->t('The "auto-add" offer can only be enabled for products that discounted 100%.'));
+      }
+    }
   }
 
   /**
@@ -238,6 +269,7 @@ class BuyXGetY extends OrderPromotionOfferBase {
       $this->configuration['buy_conditions'] = $values['buy']['conditions'];
       $this->configuration['get_quantity'] = $values['get']['quantity'];
       $this->configuration['get_conditions'] = $values['get']['conditions'];
+      $this->configuration['get_auto_add'] = $values['get']['auto_add'];
       $this->configuration['offer_type'] = $values['offer']['type'];
       if ($this->configuration['offer_type'] == 'percentage') {
         $this->configuration['offer_percentage'] = Calculator::divide((string) $values['offer']['percentage'], '100');
@@ -269,22 +301,18 @@ class BuyXGetY extends OrderPromotionOfferBase {
     }
 
     $get_conditions = $this->buildConditionGroup($this->configuration['get_conditions']);
-    // @todo Make this behavior optional based on an additional promotion
-    //   setting.
-    if ($get_purchasable_entity = $this->findSinglePurchasableEntity($get_conditions)) {
+    if ($this->configuration['get_auto_add'] && ($get_purchasable_entity = $this->findSinglePurchasableEntity($get_conditions))) {
       $order_item = $this->findOrCreateOrderItem($get_purchasable_entity, $order_items);
       $expected_get_quantity = $this->calculateExpectedGetQuantity($buy_quantities, $order_item);
 
-      // If the expected get quantity is non-zero, we need to either find an
-      // existing order item and update its quantity if needed, or create a new
-      // order item for $get_purchasable_entity.
+      // If the expected get quantity is non-zero, we need to update the
+      // quantity of the 'get' order item accordingly.
       if (Calculator::compare($expected_get_quantity, '0') !== 0) {
         if (Calculator::compare($order_item->getQuantity(), $expected_get_quantity) === -1) {
           $order_item->setQuantity($expected_get_quantity);
         }
 
         if ($order_item->isNew()) {
-          $order_item->set('order_id', $order->id());
           $order_item->save();
           $order->addItem($order_item);
           $order_items = $order->getItems();
@@ -423,12 +451,12 @@ class BuyXGetY extends OrderPromotionOfferBase {
         $purchasable_entity_ids = $condition->getPurchasableEntityIds();
         if (count($purchasable_entity_ids) === 1) {
           $purchasable_entities = $condition->getPurchasableEntities();
-          continue;
+          return reset($purchasable_entities);
         }
       }
     }
 
-    return !empty($purchasable_entities) ? reset($purchasable_entities) : NULL;
+    return NULL;
   }
 
   /**
@@ -505,6 +533,40 @@ class BuyXGetY extends OrderPromotionOfferBase {
     return $expected_get_quantity;
   }
 
+  /**
+   * Gets the #states visibility array for the 'auto_add' form element.
+   *
+   * @return array
+   *   An array of visibility options for a form element's #state property.
+   */
+  protected function getAutoAddStatesVisibility() {
+    // The 'auto_add' form element has to be shown if _any_ condition that
+    // provides a purchasable entity is enabled for the 'get' conditions. This
+    // means we need to construct a list of OR statements for #states, which
+    // looks like this:
+    // '#states' => [
+    //   'visible' => [
+    //     [':input[name="some_element"]' => ['checked' => TRUE]],
+    //     'or',
+    //     [':input[name="another_element"]' => ['checked' => TRUE]],
+    //     ...
+    //   ],
+    // ],
+    $conditions = array_filter($this->conditionManager->getFilteredDefinitions('commerce_promotion', ['commerce_order_item']), function ($definition) {
+      return is_subclass_of($definition['class'], PurchasableEntityConditionInterface::class);
+    });
+
+    $states_visibility = array_map(function ($value) {
+      return [':input[name="offer[0][target_plugin_configuration][order_buy_x_get_y][get][conditions][products][' . $value . '][enable]"]' => ['checked' => TRUE]];
+    }, array_keys($conditions));
+
+    for ($i = 0; $i < count($conditions) - 1; $i++) {
+      array_splice($states_visibility, $i + 1, 0, 'or');
+    }
+
+    return $states_visibility;
+  }
+
   /**
    * Takes a slice from the given quantity list.
    *