diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 23091d5..bdcfc9c 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -137,6 +137,7 @@ public function getFunctions() {
       new \Twig_SimpleFunction('link', array($this, 'getLink')),
       new \Twig_SimpleFunction('file_url', 'file_create_url'),
       new \Twig_SimpleFunction('attach_library', [$this, 'attachLibrary']),
+      new \Twig_SimpleFunction('active_theme_path', [$this, 'getActiveThemePath']),
       new \Twig_SimpleFunction('active_theme', [$this, 'getActiveTheme']),
     ];
   }
@@ -295,6 +296,16 @@ public function getActiveTheme() {
   }
 
   /**
+   * Gets the path of the active theme.
+   *
+   * @return string
+   *   The path to the active theme.
+   */
+  public function getActiveThemePath() {
+    return $this->themeManager->getActiveTheme()->getPath();
+  }
+
+  /**
    * Determines at compile time whether the generated URL will be safe.
    *
    * Saves the unneeded automatic escaping for performance reasons.
@@ -361,6 +372,8 @@ public function attachLibrary($library) {
    *
    * @return string|null
    *   The escaped, rendered output, or NULL if there is no valid output.
+   *
+   * @throws \Exception
    */
   public function escapePlaceholder($env, $string) {
     return '<em class="placeholder">' . $this->escapeFilter($env, $string) . '</em>';
@@ -474,6 +487,8 @@ public function escapeFilter(\Twig_Environment $env, $arg, $strategy = 'html', $
    *
    * @see render
    * @see TwigNodeVisitor
+   *
+   * @throws \Exception
    */
   public function renderVar($arg) {
     // Check for a numeric zero int or float.
diff --git a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
index 01c1bc5..e7fa8fb 100644
--- a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
+++ b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
@@ -105,6 +105,7 @@ public function testActiveTheme() {
   }
 
   /**
+<<<<<<< HEAD
    * Tests the format_date filter.
    */
   public function testFormatDate() {
@@ -126,6 +127,33 @@ public function testFormatDate() {
   }
 
   /**
+   * Tests the active_theme_path function.
+   */
+  public function testActiveThemePath() {
+    $renderer = $this->getMock('\Drupal\Core\Render\RendererInterface');
+    $extension = new TwigExtension($renderer);
+    $theme_manager = $this->getMock('\Drupal\Core\Theme\ThemeManagerInterface');
+    $active_theme = $this->getMockBuilder('\Drupal\Core\Theme\ActiveTheme')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $active_theme
+      ->expects($this->once())
+      ->method('getPath')
+      ->willReturn('foo/bar');
+    $theme_manager
+      ->expects($this->once())
+      ->method('getActiveTheme')
+      ->willReturn($active_theme);
+    $extension->setThemeManager($theme_manager);
+
+    $loader = new \Twig_Loader_String();
+    $twig = new \Twig_Environment($loader);
+    $twig->addExtension($extension);
+    $result = $twig->render('{{ active_theme_path() }}');
+    $this->assertEquals('foo/bar', $result);
+  }
+
+  /**
    * Tests the escaping of objects implementing MarkupInterface.
    *
    * @covers ::escapeFilter