diff --git a/History.markdown b/History.markdown
index 7402aa80..9824648e 100644
--- a/History.markdown
+++ b/History.markdown
@@ -79,6 +79,14 @@
 
   * Improvements to CSS (#7834)
 
+## 4.2.1 / 2021-09-27
+
+### Bug Fixes
+
+  * Backport #8620 for v4.2.x: Revert #7253: "Don't reset site.url to localhost:4000 by default" (#8808)
+  * Backport #8756 for v4.2.x: Respect collections_dir config within include tag (#8794)
+  * Backport #8786 for v4.2.x: Fix regression in Convertible module from v4.2.0 (#8793)
+
 ## 4.2.0 / 2020-12-14
 
 ### Minor Enhancements
diff --git a/docs/_config.yml b/docs/_config.yml
index 1c6c1151..4fe4dbce 100644
--- a/docs/_config.yml
+++ b/docs/_config.yml
@@ -1,5 +1,5 @@
 ---
-version: 4.2.0
+version: 4.2.1
 name: Jekyll • Simple, blog-aware, static sites
 description: Transform your plain text into static websites and blogs
 url: https://jekyllrb.com
diff --git a/docs/_docs/history.md b/docs/_docs/history.md
index 621f0d28..d377478c 100644
--- a/docs/_docs/history.md
+++ b/docs/_docs/history.md
@@ -4,6 +4,17 @@ permalink: "/docs/history/"
 note: This file is autogenerated. Edit /History.markdown instead.
 ---
 
+## 4.2.1 / 2021-09-27
+{: #v4-2-1}
+
+### Bug Fixes
+{: #bug-fixes-v4-2-1}
+
+- Backport [#8620]({{ site.repository }}/issues/8620) for v4.2.x: Revert [#7253]({{ site.repository }}/issues/7253): "Don't reset site.url to localhost:4000 by default" ([#8808]({{ site.repository }}/issues/8808))
+- Backport [#8756]({{ site.repository }}/issues/8756) for v4.2.x: Respect collections_dir config within include tag ([#8794]({{ site.repository }}/issues/8794))
+- Backport [#8786]({{ site.repository }}/issues/8786) for v4.2.x: Fix regression in Convertible module from v4.2.0 ([#8793]({{ site.repository }}/issues/8793))
+
+
 ## 4.2.0 / 2020-12-14
 {: #v4-2-0}
 
@@ -1672,7 +1683,7 @@ note: This file is autogenerated. Edit /History.markdown instead.
 ### Minor Enhancements
 {: #minor-enhancements-v3-2-0}
 
-- Stop testing with Ruby 2.0.x, which is EOL'd. ([#4381]({{ site.repository }}/issues/4381))
+- Stop testing with Ruby 2.0.x EOL ([#4381]({{ site.repository }}/issues/4381))
 - Allow collections to have documents that have no file extension ([#4545]({{ site.repository }}/issues/4545))
 - Add size property to `group_by` result ([#4557]({{ site.repository }}/issues/4557))
 - Site Template: Removed unnecessary nesting from `_base.scss` ([#4637]({{ site.repository }}/issues/4637))
diff --git a/docs/latest_version.txt b/docs/latest_version.txt
index 6aba2b24..fae6e3d0 100644
--- a/docs/latest_version.txt
+++ b/docs/latest_version.txt
@@ -1 +1 @@
-4.2.0
+4.2.1
diff --git a/lib/jekyll/version.rb b/lib/jekyll/version.rb
index 1b23b987..f6cd7edd 100644
--- a/lib/jekyll/version.rb
+++ b/lib/jekyll/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Jekyll
-  VERSION = "4.2.0"
+  VERSION = "4.2.1"
 end