diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8569e5ec7b..487eb8520d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -343,7 +343,7 @@ if(NOT OPTION_DEDICATED)
     endif()
 endif()
 
-include(CheckAtomic)
+include(3rdparty/llvm/CheckAtomic)
 
 if(APPLE)
     link_package(Iconv TARGET Iconv::Iconv)
diff --git a/README.md b/README.md
index 7b78c4248f..96a3a6eb93 100644
--- a/README.md
+++ b/README.md
@@ -212,8 +212,8 @@ See `src/3rdparty/monocypher/LICENSE.md` for the complete license text.
 The OpenTTD Social Integration API in `src/3rdparty/openttd_social_integration_api` is licensed under the MIT license.
 See `src/3rdparty/openttd_social_integration_api/LICENSE` for the complete license text.
 
-The atomic datatype support detection in `cmake/CheckAtomic.cmake` is licensed under the Apache 2.0 license.
-See `src/3rdparty/llvm/14.0.0-LICENSE.TXT` for the complete license text.
+The atomic datatype support detection in `cmake/3rdparty/llvm/CheckAtomic.cmake` is licensed under the Apache 2.0 license.
+See `cmake/3rdparty/llvm/LICENSE.txt` for the complete license text.
 
 ## 4.0 Credits
 
diff --git a/cmake/CheckAtomic.cmake b/cmake/3rdparty/llvm/CheckAtomic.cmake
similarity index 90%
rename from cmake/CheckAtomic.cmake
rename to cmake/3rdparty/llvm/CheckAtomic.cmake
index 990c52c37c..2dc895d75b 100644
--- a/cmake/CheckAtomic.cmake
+++ b/cmake/3rdparty/llvm/CheckAtomic.cmake
@@ -1,3 +1,11 @@
+#
+# This was originally part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See (https://llvm.org/)LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+# Modifications have been made to suit building OpenTTD.
+#
+
 # atomic builtins are required for threading support.
 
 INCLUDE(CheckCXXSourceCompiles)
diff --git a/src/3rdparty/llvm/14.0.0-LICENSE.TXT b/cmake/3rdparty/llvm/LICENSE.txt
similarity index 100%
rename from src/3rdparty/llvm/14.0.0-LICENSE.TXT
rename to cmake/3rdparty/llvm/LICENSE.txt