diff --git a/core/modules/aggregator/src/Plugin/aggregator/processor/DefaultProcessor.php b/core/modules/aggregator/src/Plugin/aggregator/processor/DefaultProcessor.php
index 199e224..f6c1412 100644
--- a/core/modules/aggregator/src/Plugin/aggregator/processor/DefaultProcessor.php
+++ b/core/modules/aggregator/src/Plugin/aggregator/processor/DefaultProcessor.php
@@ -11,6 +11,7 @@
 use Drupal\aggregator\Plugin\AggregatorPluginSettingsBase;
 use Drupal\aggregator\Plugin\ProcessorInterface;
 use Drupal\aggregator\FeedInterface;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Database\Database;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Datetime\DateFormatter;
@@ -213,8 +214,8 @@ public function process(FeedInterface $feed) {
       }
 
       // Make sure the item title and author fit in the 255 varchar column.
-      $entry->setTitle(truncate_utf8($item['title'], 255, TRUE, TRUE));
-      $entry->setAuthor(truncate_utf8($item['author'], 255, TRUE, TRUE));
+      $entry->setTitle(Unicode::truncate($item['title'], 255, TRUE, TRUE));
+      $entry->setAuthor(Unicode::truncate($item['author'], 255, TRUE, TRUE));
 
       $entry->setFeedId($feed->id());
       $entry->setLink($item['link']);
diff --git a/core/modules/dblog/src/Tests/DbLogTest.php b/core/modules/dblog/src/Tests/DbLogTest.php
index d397493..fe86e88 100644
--- a/core/modules/dblog/src/Tests/DbLogTest.php
+++ b/core/modules/dblog/src/Tests/DbLogTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\dblog\Tests;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Component\Utility\Xss;
 use Drupal\Core\Logger\RfcLogLevel;
 use Drupal\dblog\Controller\DbLogController;
@@ -296,7 +297,7 @@ private function doUser() {
     $this->assertLogMessage(t('Session closed for %name.', array('%name' => $name)), 'DBLog event was recorded: [logout user]');
     // Delete user.
     $message = t('Deleted user: %name %email.', array('%name' => $name, '%email' => '<' . $user->getEmail() . '>'));
-    $message_text = truncate_utf8(Xss::filter($message, array()), 56, TRUE, TRUE);
+    $message_text = Unicode::truncate(Xss::filter($message, array()), 56, TRUE, TRUE);
     // Verify that the full message displays on the details page.
     $link = FALSE;
     if ($links = $this->xpath('//a[text()="' . html_entity_decode($message_text) . '"]')) {
@@ -649,7 +650,7 @@ protected function asText(\SimpleXMLElement $element) {
    *   The message to pass to simpletest.
    */
   protected function assertLogMessage($log_message, $message) {
-    $message_text = truncate_utf8(Xss::filter($log_message, array()), 56, TRUE, TRUE);
+    $message_text = Unicode::truncate(Xss::filter($log_message, array()), 56, TRUE, TRUE);
     // After \Drupal\Component\Utility\Xss::filter(), HTML entities should be
     // converted to their character equivalents because assertLink() uses this
     // string in xpath() to query the Document Object Model (DOM).
diff --git a/core/modules/field_ui/src/FieldOverview.php b/core/modules/field_ui/src/FieldOverview.php
index 838c116..312832f 100644
--- a/core/modules/field_ui/src/FieldOverview.php
+++ b/core/modules/field_ui/src/FieldOverview.php
@@ -8,6 +8,7 @@
 namespace Drupal\field_ui;
 
 use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Entity\EntityListBuilderInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
@@ -228,7 +229,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $entity_t
           '@label' => $info['label'],
           '@field' => $info['field'],
         ));
-        $existing_field_options[$field_name] = truncate_utf8($text, 80, FALSE, TRUE);
+        $existing_field_options[$field_name] = Unicode::truncate($text, 80, FALSE, TRUE);
       }
       asort($existing_field_options);
       $name = '_add_existing_field';
diff --git a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
index 3aabb67..ff7b1b4 100644
--- a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
+++ b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
@@ -8,6 +8,7 @@
 namespace Drupal\link\Plugin\Field\FieldFormatter;
 
 use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\FormatterBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -142,7 +143,7 @@ public function viewElements(FieldItemListInterface $items) {
 
       // Trim the link text to the desired length.
       if (!empty($settings['trim_length'])) {
-        $link_title = truncate_utf8($link_title, $settings['trim_length'], FALSE, TRUE);
+        $link_title = Unicode::truncate($link_title, $settings['trim_length'], FALSE, TRUE);
       }
 
       if (!empty($settings['url_only']) && !empty($settings['url_plain'])) {
diff --git a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkSeparateFormatter.php b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkSeparateFormatter.php
index a32e611..c88b8ff 100644
--- a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkSeparateFormatter.php
+++ b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkSeparateFormatter.php
@@ -12,6 +12,7 @@
 
 namespace Drupal\link\Plugin\Field\FieldFormatter;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Field\FieldItemListInterface;
 
 /**
@@ -67,8 +68,8 @@ public function viewElements(FieldItemListInterface $items) {
       }
       $url_title = $url->toString();
       if (!empty($settings['trim_length'])) {
-        $link_title = truncate_utf8($link_title, $settings['trim_length'], FALSE, TRUE);
-        $url_title = truncate_utf8($url_title, $settings['trim_length'], FALSE, TRUE);
+        $link_title = Unicode::truncate($link_title, $settings['trim_length'], FALSE, TRUE);
+        $url_title = Unicode::truncate($url_title, $settings['trim_length'], FALSE, TRUE);
       }
 
       $element[$delta] = array(
diff --git a/core/modules/link/src/Tests/LinkFieldTest.php b/core/modules/link/src/Tests/LinkFieldTest.php
index 4bd30cd..223acdb 100644
--- a/core/modules/link/src/Tests/LinkFieldTest.php
+++ b/core/modules/link/src/Tests/LinkFieldTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\link\Tests;
 
 use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\Unicode;
 use Drupal\link\LinkItemInterface;
 use Drupal\simpletest\WebTestBase;
 
@@ -384,11 +385,11 @@ function testLinkFormatter() {
         switch ($setting) {
           case 'trim_length':
             $url = $url1;
-            $title = isset($new_value) ? truncate_utf8($title1, $new_value, FALSE, TRUE) : $title1;
+            $title = isset($new_value) ? Unicode::truncate($title1, $new_value, FALSE, TRUE) : $title1;
             $this->assertRaw('<a href="' . String::checkPlain($url) . '">' . String::checkPlain($title) . '</a>');
 
             $url = $url2;
-            $title = isset($new_value) ? truncate_utf8($title2, $new_value, FALSE, TRUE) : $title2;
+            $title = isset($new_value) ? Unicode::truncate($title2, $new_value, FALSE, TRUE) : $title2;
             $this->assertRaw('<a href="' . String::checkPlain($url) . '">' . String::checkPlain($title) . '</a>');
             break;
 
@@ -503,15 +504,15 @@ function testLinkSeparateFormatter() {
         switch ($setting) {
           case 'trim_length':
             $url = $url1;
-            $url_title = isset($new_value) ? truncate_utf8($url, $new_value, FALSE, TRUE) : $url;
+            $url_title = isset($new_value) ? Unicode::truncate($url, $new_value, FALSE, TRUE) : $url;
             $expected = '<div class="link-item">';
             $expected .= '<div class="link-url"><a href="' . String::checkPlain($url) . '">' . String::checkPlain($url_title) . '</a></div>';
             $expected .= '</div>';
             $this->assertRaw($expected);
 
             $url = $url2;
-            $url_title = isset($new_value) ? truncate_utf8($url, $new_value, FALSE, TRUE) : $url;
-            $title = isset($new_value) ? truncate_utf8($title2, $new_value, FALSE, TRUE) : $title2;
+            $url_title = isset($new_value) ? Unicode::truncate($url, $new_value, FALSE, TRUE) : $url;
+            $title = isset($new_value) ? Unicode::truncate($title2, $new_value, FALSE, TRUE) : $title2;
             $expected = '<div class="link-item">';
             $expected .= '<div class="link-title">' . String::checkPlain($title) . '</div>';
             $expected .= '<div class="link-url"><a href="' . String::checkPlain($url) . '">' . String::checkPlain($url_title) . '</a></div>';
diff --git a/core/modules/path/src/Controller/PathController.php b/core/modules/path/src/Controller/PathController.php
index 5f6f3c6..c56097c 100644
--- a/core/modules/path/src/Controller/PathController.php
+++ b/core/modules/path/src/Controller/PathController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\path\Controller;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Path\AliasStorageInterface;
 use Drupal\Core\Path\AliasManagerInterface;
@@ -74,10 +75,10 @@ public function adminOverview($keys) {
     $destination = drupal_get_destination();
     foreach ($this->aliasStorage->getAliasesForAdminListing($header, $keys) as $data) {
       $row = array();
-      $row['data']['alias'] = _l(truncate_utf8($data->alias, 50, FALSE, TRUE), $data->source, array(
+      $row['data']['alias'] = _l(Unicode::truncate($data->alias, 50, FALSE, TRUE), $data->source, array(
         'attributes' => array('title' => $data->alias),
       ));
-      $row['data']['source'] = _l(truncate_utf8($data->source, 50, FALSE, TRUE), $data->source, array(
+      $row['data']['source'] = _l(Unicode::truncate($data->source, 50, FALSE, TRUE), $data->source, array(
         'alias' => TRUE,
         'attributes' => array('title' => $data->source),
       ));
diff --git a/core/modules/search/search.module b/core/modules/search/search.module
index c622556..7e57bca 100644
--- a/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -357,7 +357,7 @@ function _search_index_truncate(&$text) {
   if (is_numeric($text)) {
     $text = ltrim($text, '0');
   }
-  $text = truncate_utf8($text, 50);
+  $text = Unicode::truncate($text, 50);
 }
 
 /**
@@ -663,7 +663,7 @@ function search_excerpt($keys, $text, $langcode = NULL) {
     // We didn't find any keyword matches, so just return the first part of the
     // text. We also need to re-encode any HTML special characters that we
     // entity-decoded above.
-    return String::checkPlain(truncate_utf8($text, 256, TRUE, TRUE));
+    return String::checkPlain(Unicode::truncate($text, 256, TRUE, TRUE));
   }
 
   // Sort the text ranges by starting position.
diff --git a/core/modules/text/text.module b/core/modules/text/text.module
index 96dcd8f..0ea98e0 100644
--- a/core/modules/text/text.module
+++ b/core/modules/text/text.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\Component\Utility\Html;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
 
@@ -98,7 +99,7 @@ function text_summary($text, $format = NULL, $size = NULL) {
   // sentence boundaries.
 
   // The summary may not be longer than maximum length specified. Initial slice.
-  $summary = truncate_utf8($text, $size);
+  $summary = Unicode::truncate($text, $size);
 
   // Store the actual length of the UTF8 string -- which might not be the same
   // as $size.