core/lib/Drupal/Core/Render/Renderer.php          | 20 +++-----------------
 core/lib/Drupal/Core/Render/RendererInterface.php | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/core/lib/Drupal/Core/Render/Renderer.php b/core/lib/Drupal/Core/Render/Renderer.php
index bae1715..c1cbc0a 100644
--- a/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -158,22 +158,7 @@ public function renderPlain(&$elements) {
   }
 
   /**
-   * Renders final HTML for a placeholder.
-   *
-   * Renders the placeholder in isolation.
-   *
-   * @param string $placeholder
-   *   An attached placeholder to render. (This must be a key of one of the
-   *   values of $elements['#attached']['placeholders'].)
-   * @param array $elements
-   *   The structured array describing the data to be rendered.
-   *
-   * @return array
-   *   The updated $elements.
-   *
-   * @see ::replacePlaceholders()
-   *
-   * @todo Make public as part of https://www.drupal.org/node/2469431
+   * {@inheritdoc}
    */
   public function renderPlaceholder($placeholder, array $elements) {
     // Get the render array for the given placeholder
@@ -196,7 +181,6 @@ public function renderPlaceholder($placeholder, array $elements) {
     return $elements;
   }
 
-
   /**
    * {@inheritdoc}
    */
@@ -648,6 +632,8 @@ protected function setCurrentRenderContext(RenderContext $context = NULL) {
    *
    * @returns bool
    *   Whether placeholders were replaced.
+   *
+   * @see ::renderPlaceholder()
    */
   protected function replacePlaceholders(array &$elements) {
     if (!isset($elements['#attached']['placeholders']) || empty($elements['#attached']['placeholders'])) {
diff --git a/core/lib/Drupal/Core/Render/RendererInterface.php b/core/lib/Drupal/Core/Render/RendererInterface.php
index ff04d86..ccbe2d5 100644
--- a/core/lib/Drupal/Core/Render/RendererInterface.php
+++ b/core/lib/Drupal/Core/Render/RendererInterface.php
@@ -67,6 +67,24 @@ public function renderRoot(&$elements);
   public function renderPlain(&$elements);
 
   /**
+   * Renders final HTML for a placeholder.
+   *
+   * Renders the placeholder in isolation.
+   *
+   * @param string $placeholder
+   *   An attached placeholder to render. (This must be a key of one of the
+   *   values of $elements['#attached']['placeholders'].)
+   * @param array $elements
+   *   The structured array describing the data to be rendered.
+   *
+   * @return array
+   *   The updated $elements.
+   *
+   * @see ::render()
+   */
+  public function renderPlaceholder($placeholder, array $elements);
+
+  /**
    * Renders HTML given a structured array tree.
    *
    * Renderable arrays have two kinds of key/value pairs: properties and