diff -u b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
--- b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
@@ -192,7 +192,7 @@
   public function testAdminXss() {
     // Mark the string as safe. This is for test purposes only.
     $text = '<marquee>text</marquee>';
-    SafeMarkup::set($text);
+    $this->safeMarkupSet($text);
 
     // SafeMarkup::escape() will not escape the markup tag since the string was
     // marked safe above.
@@ -213,7 +213,7 @@
   public function testAdminXss() {
     // Mark the string as safe. This is for test purposes only.
     $text = '<marquee>text</marquee>';
-    $this->safeMarkupSet($text);
+    SafeMarkup::set($text);
 
     // SafeMarkup::escape() will not escape the markup tag since the string was
     // marked safe above.
@@ -223,7 +223,7 @@
  * Marks text as safe.
  *
  * SafeMarkupTestSafeString is used to mark text as safe because
- * SafeMarkup::set() is a global static that affects all tests.
+ * SafeMarkup::$safeStrings is a global static that affects all tests.
  */
 class SafeMarkupTestSafeString implements SafeStringInterface {
 
@@ -301,7 +301,7 @@
  * Marks text as safe.
  *
  * SafeMarkupTestSafeString is used to mark text as safe because
- * SafeMarkup::$safeStrings is a global static that affects all tests.
+ * SafeMarkup::set() is a global static that affects all tests.
  */
 class SafeMarkupTestSafeString implements SafeStringInterface {
 
only in patch2:
unchanged:
--- a/core/lib/Drupal/Component/Utility/SafeMarkup.php
+++ b/core/lib/Drupal/Component/Utility/SafeMarkup.php
@@ -35,57 +35,22 @@ class SafeMarkup {
   /**
    * The list of safe strings.
    *
+   * Strings in this list are marked as secure for the entire page render, not
+   * just the code or element that set it. Therefore, only valid HTML should be
+   * marked as safe (never partial markup). For example, you should never mark
+   * string such as '<' or '<script>' safe.
+   *
    * @var array
    */
   protected static $safeStrings = array();
 
   /**
-   * Adds a string to a list of strings marked as secure.
-   *
-   * This method is for internal use. Do not use it to prevent escaping of
-   * markup; instead, use the appropriate
-   * @link sanitization sanitization functions @endlink or the
-   * @link theme_render theme and render systems @endlink so that the output
-   * can be themed, escaped, and altered properly.
-   *
-   * This marks strings as secure for the entire page render, not just the code
-   * or element that set it. Therefore, only valid HTML should be
-   * marked as safe (never partial markup). For example, you should never do:
-   * @code
-   *   SafeMarkup::set('<');
-   * @endcode
-   * or:
-   * @code
-   *   SafeMarkup::set('<script>');
-   * @endcode
-   *
-   * @param string $string
-   *   The content to be marked as secure.
-   * @param string $strategy
-   *   The escaping strategy used for this string. Two values are supported
-   *   by default:
-   *   - 'html': (default) The string is safe for use in HTML code.
-   *   - 'all': The string is safe for all use cases.
-   *   See the
-   *   @link http://twig.sensiolabs.org/doc/filters/escape.html Twig escape documentation @endlink
-   *   for more information on escaping strategies in Twig.
-   *
-   * @return string
-   *   The input string that was marked as safe.
-   */
-  public static function set($string, $strategy = 'html') {
-    $string = (string) $string;
-    static::$safeStrings[$string][$strategy] = TRUE;
-    return $string;
-  }
-
-  /**
    * Checks if a string is safe to output.
    *
    * @param string|\Drupal\Component\Utility\SafeStringInterface $string
    *   The content to be checked.
    * @param string $strategy
-   *   The escaping strategy. See self::set(). Defaults to 'html'.
+   *   The escaping strategy. See self::setMultiple(). Defaults to 'html'.
    *
    * @return bool
    *   TRUE if the string has been marked secure, FALSE otherwise.
@@ -100,12 +65,23 @@ public static function isSafe($string, $strategy = 'html') {
   /**
    * Adds previously retrieved known safe strings to the safe string list.
    *
-   * This is useful for the batch and form APIs, where it is important to
-   * preserve the safe markup state across page requests. The strings will be
-   * added to any safe strings already marked for the current request.
+   * This method is for internal use only. It is used in the batch and form
+   * APIs, where it is important to preserve the safe markup state across page
+   * requests. The strings will be added to any safe strings already marked for
+   * the current request.
    *
    * @param array $safe_strings
    *   A list of safe strings as previously retrieved by self::getAll().
+   *   every string in this list will be represented by a an associative
+   *   array with as key the string and as value an asssociative array
+   *   with the escaping strategy used for this string as a key and
+   *   the boolean TRUE as a value. Two escaping strategies are supported
+   *   by default:
+   *   - 'html': (default) The string is safe for use in HTML code.
+   *   - 'all': The string is safe for all use cases.
+   *   See the
+   *   @link http://twig.sensiolabs.org/doc/filters/escape.html Twig escape documentation @endlink
+   *   for more information on escaping strategies in Twig.
    *
    * @throws \UnexpectedValueException
    */
@@ -131,8 +107,8 @@ public static function setMultiple(array $safe_strings) {
    *   A string.
    *
    * @return string
-   *   The escaped string. If $string was already set as safe with
-   *   self::set(), it won't be escaped again.
+   *   The escaped string. If $string was already set as safe previously, it
+   *   won't be escaped again.
    */
   public static function escape($string) {
     return static::isSafe($string) ? $string : static::checkPlain($string);
only in patch2:
unchanged:
--- a/core/lib/Drupal/Component/Utility/SafeStringInterface.php
+++ b/core/lib/Drupal/Component/Utility/SafeStringInterface.php
@@ -29,7 +29,6 @@
  *   and to fast render fields.
  *
  * @see \Drupal\Component\Utility\SafeStringTrait
- * @see \Drupal\Component\Utility\SafeMarkup::set()
  * @see \Drupal\Component\Utility\SafeMarkup::isSafe()
  * @see \Drupal\Core\Template\TwigExtension::escapeFilter()
  */
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php
+++ b/core/tests/Drupal/Tests/Core/Utility/LinkGeneratorTest.php
@@ -372,8 +372,8 @@ public function testGenerateWithHtml() {
     ), $result);
 
     // Test that safe HTML is output inside the anchor tag unescaped. The
-    // SafeMarkup::set() call is an intentional unit test for the interaction
-    // between SafeMarkup and the LinkGenerator.
+    // SafeString::create() call is an intentional unit test for the interaction
+    // between SafeString::create() and the LinkGenerator.
     $url = new Url('test_route_5', array());
     $url->setUrlGenerator($this->urlGenerator);
     $result = $this->linkGenerator->generate(SafeString::create('<em>HTML output</em>'), $url);