diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 07f3cf26fd..16c072d6a9 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -563,6 +563,7 @@ Variables that Control the Build
    /variable/CMAKE_TRY_COMPILE_TARGET_TYPE
    /variable/CMAKE_UNITY_BUILD
    /variable/CMAKE_UNITY_BUILD_BATCH_SIZE
+   /variable/CMAKE_UNITY_BUILD_RELOCATABLE
    /variable/CMAKE_UNITY_BUILD_UNIQUE_ID
    /variable/CMAKE_VERIFY_INTERFACE_HEADER_SETS
    /variable/CMAKE_VISIBILITY_INLINES_HIDDEN
diff --git a/Help/variable/CMAKE_UNITY_BUILD_RELOCATABLE.rst b/Help/variable/CMAKE_UNITY_BUILD_RELOCATABLE.rst
new file mode 100644
index 0000000000..09bc5cc26e
--- /dev/null
+++ b/Help/variable/CMAKE_UNITY_BUILD_RELOCATABLE.rst
@@ -0,0 +1,9 @@
+CMAKE_UNITY_BUILD_RELOCATABLE
+-----------------------------
+
+.. versionadded:: 4.0
+
+This variable is used to initialize the :prop_tgt:`UNITY_BUILD_RELOCATABLE`
+property of targets when they are created.  Setting it to true causes
+sources generated for :variable:`CMAKE_UNITY_BUILD` to ``#include`` the
+original source files using relative paths where possible.