diff --git a/src/wp-includes/option.php b/src/wp-includes/option.php
index 566c896331..2f548e6151 100644
--- a/src/wp-includes/option.php
+++ b/src/wp-includes/option.php
@@ -221,12 +221,15 @@ function wp_load_core_site_options( $site_id = null ) {
  * to set whether an option is autoloaded, then you need to use the add_option().
  *
  * @since 1.0.0
+ * @since 4.2.0 The `$autoload` parameter was added.
  *
- * @param string $option Option name. Expected to not be SQL-escaped.
- * @param mixed $value Option value. Must be serializable if non-scalar. Expected to not be SQL-escaped.
+ * @param string      $option   Option name. Expected to not be SQL-escaped.
+ * @param mixed       $value    Option value. Must be serializable if non-scalar. Expected to not be SQL-escaped.
+ * @param string|bool $autoload Optional. Whether to load the option when WordPress starts up. Accepts 'yes' or true to
+ *                              enable, 'no' or false to disable. Default is enabled.
  * @return bool False if value was not updated and true if value was updated.
  */
-function update_option( $option, $value ) {
+function update_option( $option, $value, $autoload = 'yes' ) {
 	global $wpdb;
 
 	$option = trim($option);
@@ -269,8 +272,9 @@ function update_option( $option, $value ) {
 		return false;
 
 	/** This filter is documented in wp-includes/option.php */
-	if ( apply_filters( 'default_option_' . $option, false ) === $old_value )
-		return add_option( $option, $value );
+	if ( apply_filters( 'default_option_' . $option, false ) === $old_value ) {
+		return add_option( $option, $value, '', $autoload );
+	}
 
 	$serialized_value = maybe_serialize( $value );
 
diff --git a/tests/phpunit/tests/option/option.php b/tests/phpunit/tests/option/option.php
index d2c8473f26..83456e0eb8 100644
--- a/tests/phpunit/tests/option/option.php
+++ b/tests/phpunit/tests/option/option.php
@@ -149,4 +149,102 @@ class Tests_Option_Option extends WP_UnitTestCase {
 		$actual = $wpdb->get_row( $wpdb->prepare( "SELECT autoload FROM $wpdb->options WHERE option_name = %s LIMIT 1", $name ) );
 		$this->assertEquals( $expected, $actual->autoload );
 	}
+
+	/**
+	 * @ticket 26394
+	 */
+	public function test_update_option_should_set_autoload_yes_for_nonexistent_option_when_autoload_param_is_missing() {
+		if ( is_multisite() ) {
+			$this->markTestSkipped( 'Not testable in MS: wpmu_create_blog() defines WP_INSTALLING, which causes cache misses.' );
+		}
+
+		global $wpdb;
+		wp_cache_flush();
+		update_option( 'test_update_option_default', 'value' );
+		wp_cache_flush();
+
+		// Populate the alloptions cache, which includes autoload=yes options.
+		wp_load_alloptions();
+
+		$before = $wpdb->num_queries;
+		$value = get_option( 'test_update_option_default' );
+		$after = $wpdb->num_queries;
+
+		$this->assertEquals( $before, $after );
+		$this->assertEquals( $value, 'value' );
+	}
+
+	/**
+	 * @ticket 26394
+	 */
+	public function test_update_option_should_set_autoload_yes_for_nonexistent_option_when_autoload_param_is_yes() {
+		if ( is_multisite() ) {
+			$this->markTestSkipped( 'Not testable in MS: wpmu_create_blog() defines WP_INSTALLING, which causes cache misses.' );
+		}
+
+		global $wpdb;
+		wp_cache_flush();
+		update_option( 'test_update_option_default', 'value', 'yes' );
+		wp_cache_flush();
+
+		// Populate the alloptions cache, which includes autoload=yes options.
+		wp_load_alloptions();
+
+		$before = $wpdb->num_queries;
+		$value = get_option( 'test_update_option_default' );
+		$after = $wpdb->num_queries;
+
+		$this->assertEquals( $before, $after );
+		$this->assertEquals( $value, 'value' );
+	}
+
+	/**
+	 * @ticket 26394
+	 */
+	public function test_update_option_should_set_autoload_yes_for_nonexistent_option_when_autoload_param_is_no() {
+		if ( is_multisite() ) {
+			$this->markTestSkipped( 'Not testable in MS: wpmu_create_blog() defines WP_INSTALLING, which causes cache misses.' );
+		}
+
+		global $wpdb;
+		wp_cache_flush();
+		update_option( 'test_update_option_default', 'value', 'no' );
+		wp_cache_flush();
+
+		// Populate the alloptions cache, which does not include autoload=no options.
+		wp_load_alloptions();
+
+		$before = $wpdb->num_queries;
+		$value = get_option( 'test_update_option_default' );
+		$after = $wpdb->num_queries;
+
+		// Database has been hit.
+		$this->assertEquals( $before + 1, $after );
+		$this->assertEquals( $value, 'value' );
+	}
+
+	/**
+	 * @ticket 26394
+	 */
+	public function test_update_option_should_set_autoload_yes_for_nonexistent_option_when_autoload_param_is_false() {
+		if ( is_multisite() ) {
+			$this->markTestSkipped( 'Not testable in MS: wpmu_create_blog() defines WP_INSTALLING, which causes cache misses.' );
+		}
+
+		global $wpdb;
+		wp_cache_flush();
+		update_option( 'test_update_option_default', 'value', false );
+		wp_cache_flush();
+
+		// Populate the alloptions cache, which does not include autoload=no options.
+		wp_load_alloptions();
+
+		$before = $wpdb->num_queries;
+		$value = get_option( 'test_update_option_default' );
+		$after = $wpdb->num_queries;
+
+		// Database has been hit.
+		$this->assertEquals( $before + 1, $after );
+		$this->assertEquals( $value, 'value' );
+	}
 }