diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst
index a0f7726c46f8..1796b3eba37b 100644
--- a/Documentation/kbuild/kbuild.rst
+++ b/Documentation/kbuild/kbuild.rst
@@ -134,6 +134,11 @@ KBUILD_OUTPUT
 -------------
 Specify the output directory when building the kernel.
 
+This variable can also be used to point to the kernel output directory when
+building external modules against a pre-built kernel in a separate build
+directory. Please note that this does NOT specify the output directory for the
+external modules themselves.
+
 The output directory can also be specified using "O=...".
 
 Setting "O=..." takes precedence over KBUILD_OUTPUT.
diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst
index 080e11372351..b24448f789b3 100644
--- a/Documentation/kbuild/modules.rst
+++ b/Documentation/kbuild/modules.rst
@@ -45,7 +45,7 @@ Command Syntax
 
 	The command to build an external module is::
 
-		$ make -C <path_to_kernel_src> M=$PWD
+		$ make -C <path_to_kernel_dir> M=$PWD
 
 	The kbuild system knows that an external module is being built
 	due to the "M=<dir>" option given in the command.
@@ -62,12 +62,15 @@ Command Syntax
 Options
 -------
 
-	($KDIR refers to the path of the kernel source directory.)
+	($KDIR refers to the path of the kernel source directory, or the path
+	of the kernel output directory if the kernel was built in a separate
+	build directory.)
 
 	make -C $KDIR M=$PWD
 
 	-C $KDIR
-		The directory where the kernel source is located.
+		The directory that contains the kernel and relevant build
+		artifacts used for building an external module.
 		"make" will actually change to the specified directory
 		when executing and will change back when finished.