diff --git a/lib/common/src/Attribute.php b/lib/common/src/Attribute.php
index 8321e408596..a7e4df5b05a 100644
--- a/lib/common/src/Attribute.php
+++ b/lib/common/src/Attribute.php
@@ -59,6 +59,8 @@ interface Attribute
     const ALL_AMP4ADS   = [self::AMP4ADS, self::AMP4ADS_EMOJI, self::AMP4ADS_EMOJI_ALT];
     const ALL_AMP4EMAIL = [self::AMP4EMAIL, self::AMP4EMAIL_EMOJI, self::AMP4EMAIL_EMOJI_ALT];
 
+    const ALL_BOILERPLATES = [self::AMP_BOILERPLATE, self::AMP4ADS_BOILERPLATE, self::AMP4EMAIL_BOILERPLATE];
+
     const TYPE_HTML    = 'text/html';
     const TYPE_JSON    = 'application/json';
     const TYPE_LD_JSON = 'application/ld+json';
diff --git a/lib/optimizer/src/Transformer/AmpBoilerplate.php b/lib/optimizer/src/Transformer/AmpBoilerplate.php
index e49d6ddfc2d..5acf7c405c6 100644
--- a/lib/optimizer/src/Transformer/AmpBoilerplate.php
+++ b/lib/optimizer/src/Transformer/AmpBoilerplate.php
@@ -4,7 +4,6 @@
 
 use AmpProject\Amp;
 use AmpProject\Attribute;
-use AmpProject\DevMode;
 use AmpProject\Dom\Document;
 use AmpProject\Optimizer\ErrorCollection;
 use AmpProject\Optimizer\Transformer;
@@ -12,8 +11,8 @@
 use DOMElement;
 
 /**
- * Transformer that removes <style> and <noscript> tags in <head>, keeping only the amp-custom style tag. It then
- * inserts the amp-boilerplate.
+ * Transformer that removes AMP boilerplate <style> and <noscript> tags in <head>, keeping only the amp-custom style tag.
+ * It then (re-)inserts the amp-boilerplate unless the document is marked with the i-amphtml-no-boilerplate attribute.
  *
  * This is ported from the Go optimizer.
  *
@@ -68,31 +67,44 @@ public function transform(Document $document, ErrorCollection $errors)
     }
 
     /**
-     * Remove all <style> and <noscript> tags except for the <style amp-custom> tag.
+     * Remove all <style> and <noscript> tags which are for the boilerplate.
      *
      * @param Document $document Document to remove the tags from.
      */
     private function removeStyleAndNoscriptTags(Document $document)
     {
-        $headNode = $document->head->firstChild;
-        $devMode = DevMode::isActiveForDocument($document);
-        while ($headNode) {
-            $nextSibling = $headNode->nextSibling;
-            if ($headNode instanceof DOMElement && (! $devMode || ! DevMode::hasExemptionForNode($headNode))) {
-                switch ($headNode->tagName) {
-                    case Tag::STYLE:
-                        if (! $headNode->hasAttribute(Attribute::AMP_CUSTOM)) {
-                            $document->head->removeChild($headNode);
-                        }
-                        break;
-                    case Tag::NOSCRIPT:
-                        $document->head->removeChild($headNode);
-                        break;
-                }
+        /**
+         * Style element.
+         *
+         * @var DOMElement $style
+         */
+        foreach (iterator_to_array($document->head->getElementsByTagName('style')) as $style) {
+            if (! $this->isBoilerplateStyle($style)) {
+                continue;
             }
+            if (Tag::NOSCRIPT === $style->parentNode->nodeName) {
+                $style->parentNode->parentNode->removeChild($style->parentNode);
+            } else {
+                $style->parentNode->removeChild($style);
+            }
+        }
+    }
 
-            $headNode = $nextSibling;
+    /**
+     * Check whether an element is a boilerplate style.
+     *
+     * @param DOMElement $element Element to check.
+     * @return bool Whether the element is a boilerplate style.
+     */
+    private function isBoilerplateStyle(DOMElement $element)
+    {
+        foreach (Attribute::ALL_BOILERPLATES as $boilerplate) {
+            if ($element->hasAttribute($boilerplate)) {
+                return true;
+            }
         }
+
+        return false;
     }
 
     /**
diff --git a/lib/optimizer/tests/Transformer/AmpBoilerplateTest.php b/lib/optimizer/tests/Transformer/AmpBoilerplateTest.php
index 1d7e7a3a5fc..b7b6ab078e6 100644
--- a/lib/optimizer/tests/Transformer/AmpBoilerplateTest.php
+++ b/lib/optimizer/tests/Transformer/AmpBoilerplateTest.php
@@ -26,27 +26,16 @@ final class AmpBoilerplateTest extends TestCase
      */
     public function dataTransform()
     {
-        $inputWithBoilerplate = static function ($html, $boilerplate) {
+        $htmlDocument = static function ($html, $headEnd = '') {
             return TestMarkup::DOCTYPE . $html . '<head>' .
                    TestMarkup::META_CHARSET . TestMarkup::META_VIEWPORT . TestMarkup::SCRIPT_AMPRUNTIME .
                    TestMarkup::LINK_FAVICON . TestMarkup::LINK_CANONICAL .
-                   $boilerplate .
+                   $headEnd .
                    '</head><body></body></html>';
         };
 
-        $inputWithoutBoilerplate = static function ($html) {
-            return TestMarkup::DOCTYPE . $html . '<head>' .
-                   TestMarkup::META_CHARSET . TestMarkup::META_VIEWPORT . TestMarkup::SCRIPT_AMPRUNTIME .
-                   TestMarkup::LINK_FAVICON . TestMarkup::LINK_CANONICAL .
-                   '</head><body></body></html>';
-        };
-
-        $expected = static function ($html, $boilerplate) {
-            return TestMarkup::DOCTYPE . $html . '<head>' .
-                   TestMarkup::META_CHARSET . TestMarkup::META_VIEWPORT . TestMarkup::SCRIPT_AMPRUNTIME .
-                   TestMarkup::LINK_FAVICON . TestMarkup::LINK_CANONICAL .
-                   $boilerplate .
-                   '</head><body></body></html>';
+        $repeatTwice = static function ($value) {
+            return array_fill(0, 2, $value);
         };
 
         $ampBoilerplate = '<style ' . Attribute::AMP_BOILERPLATE . '>' . Amp::BOILERPLATE_CSS . '</style>' .
@@ -57,65 +46,81 @@ public function dataTransform()
         $amp4EmailBoilerplate = '<style ' . Attribute::AMP4EMAIL_BOILERPLATE . '>' . Amp::AMP4ADS_AND_AMP4EMAIL_BOILERPLATE_CSS . '</style>';
 
         return [
-            'keeps boilerplate' => [
-                $inputWithBoilerplate('<html ⚡>', $ampBoilerplate),
-                $expected('<html ⚡>', $ampBoilerplate),
-            ],
+            'keeps boilerplate' => $repeatTwice(
+                $htmlDocument('<html ⚡>', $ampBoilerplate)
+            ),
 
-            'keeps boilerplate for amp4ads' => [
-                $inputWithBoilerplate('<html amp4ads>', $amp4AdsBoilerplate),
-                $expected('<html amp4ads>', $amp4AdsBoilerplate),
-            ],
+            'keeps boilerplate again' => $repeatTwice(
+                $htmlDocument('<html amp>', $ampBoilerplate)
+            ),
 
-            'keeps boilerplate for ⚡4ads' => [
-                $inputWithBoilerplate('<html ⚡4ads>', $amp4AdsBoilerplate),
-                $expected('<html ⚡4ads>', $amp4AdsBoilerplate),
+            'removes incorrect boilerplates' => [
+                $htmlDocument('<html amp>', $ampBoilerplate . $amp4AdsBoilerplate . $amp4EmailBoilerplate),
+                $htmlDocument('<html amp>', $ampBoilerplate),
             ],
 
-            'keeps boilerplate for amp4email' => [
-                $inputWithBoilerplate('<html amp4email>', $amp4EmailBoilerplate),
-                $expected('<html amp4email>', $amp4EmailBoilerplate),
-            ],
+            'leaves out boilerplate' => $repeatTwice(
+                $htmlDocument('<html amp i-amphtml-no-boilerplate>')
+            ),
 
-            'keeps boilerplate for ⚡4email' => [
-                $inputWithBoilerplate('<html ⚡4email>', $amp4EmailBoilerplate),
-                $expected('<html ⚡4email>', $amp4EmailBoilerplate),
+            'removes boilerplate' => [
+                $htmlDocument('<html amp i-amphtml-no-boilerplate>', $ampBoilerplate),
+                $htmlDocument('<html amp i-amphtml-no-boilerplate>'),
             ],
 
+            'keeps boilerplate for amp4ads' => $repeatTwice(
+                $htmlDocument('<html amp4ads>', $amp4AdsBoilerplate)
+            ),
+
+            'keeps boilerplate for ⚡4ads' => $repeatTwice(
+                $htmlDocument('<html ⚡4ads>', $amp4AdsBoilerplate)
+            ),
+
+            'keeps boilerplate for amp4email' => $repeatTwice(
+                $htmlDocument('<html amp4email>', $amp4EmailBoilerplate)
+            ),
+
+            'keeps boilerplate for ⚡4email' => $repeatTwice(
+                $htmlDocument('<html ⚡4email>', $amp4EmailBoilerplate)
+            ),
+
             'adds boilerplate if missing' => [
-                $inputWithoutBoilerplate('<html ⚡>'),
-                $expected('<html ⚡>', $ampBoilerplate),
+                $htmlDocument('<html ⚡>'),
+                $htmlDocument('<html ⚡>', $ampBoilerplate),
             ],
 
             'adds boilerplate if missing for amp4ads' => [
-                $inputWithoutBoilerplate('<html amp4ads>'),
-                $expected('<html amp4ads>', $amp4AdsBoilerplate),
+                $htmlDocument('<html amp4ads>'),
+                $htmlDocument('<html amp4ads>', $amp4AdsBoilerplate),
             ],
 
             'adds boilerplate if missing for ⚡4ads' => [
-                $inputWithoutBoilerplate('<html ⚡4ads>'),
-                $expected('<html ⚡4ads>', $amp4AdsBoilerplate),
+                $htmlDocument('<html ⚡4ads>'),
+                $htmlDocument('<html ⚡4ads>', $amp4AdsBoilerplate),
             ],
 
             'adds boilerplate if missing for amp4email' => [
-                $inputWithoutBoilerplate('<html amp4email>'),
-                $expected('<html amp4email>', $amp4EmailBoilerplate),
+                $htmlDocument('<html amp4email>'),
+                $htmlDocument('<html amp4email>', $amp4EmailBoilerplate),
             ],
 
             'adds boilerplate if missing for ⚡4email' => [
-                $inputWithoutBoilerplate('<html ⚡4email>'),
-                $expected('<html ⚡4email>', $amp4EmailBoilerplate),
+                $htmlDocument('<html ⚡4email>'),
+                $htmlDocument('<html ⚡4email>', $amp4EmailBoilerplate),
             ],
 
-            'keeps devmode nodes when in devmode' => [
-                $inputWithBoilerplate('<html ⚡ data-ampdevmode>', '<style data-ampdevmode>h1: red;</style>' . $ampBoilerplate),
-                $expected('<html ⚡ data-ampdevmode>', '<style data-ampdevmode>h1: red;</style>' . $ampBoilerplate),
-            ],
+            'leaves styles that lack boilerplate attribute' => $repeatTwice(
+                $htmlDocument('<html ⚡>', '<style>h1{color:red}</style><noscript><style>h2{color:blue}</style></noscript>' . $ampBoilerplate)
+            ),
 
-            'removes devmode nodes when not in devmode' => [
-                $inputWithBoilerplate('<html ⚡>', '<style data-ampdevmode>h1: red;</style>' . $ampBoilerplate),
-                $expected('<html ⚡>', $ampBoilerplate),
+            'leaves styles that lack boilerplate attribute and adds boilerplate' => [
+                $htmlDocument('<html ⚡>', '<style>h1{color:red}</style><noscript><style>h2{color:blue}</style></noscript>'),
+                $htmlDocument('<html ⚡>', '<style>h1{color:red}</style><noscript><style>h2{color:blue}</style></noscript>' . $ampBoilerplate),
             ],
+
+            'leaves styles that lack boilerplate attribute and leaves out boilerplate' => $repeatTwice(
+                $htmlDocument('<html amp i-amphtml-no-boilerplate>', '<style>h1{color:red}</style><noscript><style>h2{color:blue}</style></noscript>')
+            ),
         ];
     }
 
