diff --git a/CHANGES.txt b/CHANGES.txt
index 93eaeefda..e3677738d 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -22,6 +22,7 @@ Other
   promising support for versions supported by the Python core team,
   Ubuntu LTS, or Debian stable, and taking into consideration
   Debian oldstable and PyPy.
+* Replace `polyfill.io` with `cdnjs.cloudflare.com/polyfill`.
 
 New in v8.3.0
 =============
diff --git a/docs/manual.rst b/docs/manual.rst
index 0f8f00ea5..3caef8504 100644
--- a/docs/manual.rst
+++ b/docs/manual.rst
@@ -1692,7 +1692,7 @@ For Mako:
     % if date_fanciness != 0:
     %if date_fanciness == 2:
         <!-- Polyfill for relative dates in Safari -- best handled with a CDN -->
-        <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
+        <script src="https://cdnjs.cloudflare.com/polyfillflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
     %endif
     <!-- required scripts -- best handled with bundles -->
     <script src="/assets/js/luxon.min.js"></script>
@@ -1714,7 +1714,7 @@ For Jinja2:
     {% if date_fanciness != 0 %}
     {% if date_fanciness == 2 %}
         <!-- Polyfill for relative dates in Safari -- best handled with a CDN -->
-        <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
+        <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
     {% endif %}
     <!-- required scripts -- best handled with bundles -->
     <script src="/assets/js/luxon.min.js"></script>
diff --git a/nikola/data/themes/base-jinja/templates/base_helper.tmpl b/nikola/data/themes/base-jinja/templates/base_helper.tmpl
index 30faac67b..27e4d9ff3 100644
--- a/nikola/data/themes/base-jinja/templates/base_helper.tmpl
+++ b/nikola/data/themes/base-jinja/templates/base_helper.tmpl
@@ -79,7 +79,7 @@ lang="{{ lang }}">
     {% endif %}
     {% if date_fanciness != 0 %}
         {% if date_fanciness == 2 %}
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
         {% endif %}
         {% if use_cdn %}
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>
diff --git a/nikola/data/themes/base/templates/base_helper.tmpl b/nikola/data/themes/base/templates/base_helper.tmpl
index a03ae5070..755c83ef4 100644
--- a/nikola/data/themes/base/templates/base_helper.tmpl
+++ b/nikola/data/themes/base/templates/base_helper.tmpl
@@ -79,7 +79,7 @@ lang="${lang}">
     % endif
     % if date_fanciness != 0:
         % if date_fanciness == 2:
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
         % endif
         % if use_cdn:
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>
diff --git a/nikola/data/themes/bootblog4-jinja/templates/base_helper.tmpl b/nikola/data/themes/bootblog4-jinja/templates/base_helper.tmpl
index be879131f..04f8ae280 100644
--- a/nikola/data/themes/bootblog4-jinja/templates/base_helper.tmpl
+++ b/nikola/data/themes/bootblog4-jinja/templates/base_helper.tmpl
@@ -83,7 +83,7 @@ lang="{{ lang }}">
     {% endif %}
     {% if date_fanciness != 0 %}
         {% if date_fanciness == 2 %}
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
         {% endif %}
         {% if use_cdn %}
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>
diff --git a/nikola/data/themes/bootblog4/templates/base_helper.tmpl b/nikola/data/themes/bootblog4/templates/base_helper.tmpl
index 7ba4e9256..aa667061c 100644
--- a/nikola/data/themes/bootblog4/templates/base_helper.tmpl
+++ b/nikola/data/themes/bootblog4/templates/base_helper.tmpl
@@ -83,7 +83,7 @@ lang="${lang}">
     %endif
     %if date_fanciness != 0:
         %if date_fanciness == 2:
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
         %endif
         %if use_cdn:
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>
diff --git a/nikola/data/themes/bootstrap4-jinja/templates/base_helper.tmpl b/nikola/data/themes/bootstrap4-jinja/templates/base_helper.tmpl
index 167e8df1f..daedd89b9 100644
--- a/nikola/data/themes/bootstrap4-jinja/templates/base_helper.tmpl
+++ b/nikola/data/themes/bootstrap4-jinja/templates/base_helper.tmpl
@@ -83,7 +83,7 @@ lang="{{ lang }}">
     {% endif %}
     {% if date_fanciness != 0 %}
         {% if date_fanciness == 2 %}
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.{{ luxon_locales[lang] }}"></script>
         {% endif %}
         {% if use_cdn %}
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>
diff --git a/nikola/data/themes/bootstrap4/templates/base_helper.tmpl b/nikola/data/themes/bootstrap4/templates/base_helper.tmpl
index c5895cd2b..7f4f9dbd4 100644
--- a/nikola/data/themes/bootstrap4/templates/base_helper.tmpl
+++ b/nikola/data/themes/bootstrap4/templates/base_helper.tmpl
@@ -83,7 +83,7 @@ lang="${lang}">
     %endif
     %if date_fanciness != 0:
         %if date_fanciness == 2:
-            <script src="https://polyfill.io/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
+            <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.js?features=Intl.RelativeTimeFormat.%7Elocale.${luxon_locales[lang]}"></script>
         %endif
         %if use_cdn:
             <script src="https://cdn.jsdelivr.net/npm/luxon@3.3.0/build/global/luxon.min.js" integrity="sha256-Nn+JGDrq3PuTxcDfJmmI0Srj5LpfOFlKqEiPwQK7y40=" crossorigin="anonymous"></script>