diff --git a/Makefile b/Makefile
index 9847f91d7c19..9b55fe6f01f3 100644
--- a/Makefile
+++ b/Makefile
@@ -89,6 +89,15 @@
 # 10.  `reboot'
 # 11.  `make delete-old-libs' (in case no 3rd party program uses them anymore)
 #
+# For individuals wanting to build from source with GCC from ports, first build
+# or install an appropriate flavor of devel/freebsd-gcc9.  The packages produced
+# by this port are named "${TARGET_ARCH}-gcc9" -- note that not all
+# architectures supported by FreeBSD have an external gcc toolchain available.
+#
+# Once the appropriate freebsd-gcc package is installed, simply pass
+# CROSS_TOOLCHAIN=${TARGET_ARCH}-gcc9 while building with the above steps,
+# e.g., `make buildworld CROSS_TOOLCHAIN=amd64-gcc9`.
+#
 # See src/UPDATING `COMMON ITEMS' for more complete information.
 #
 # If TARGET=machine (e.g. powerpc, arm64, ...) is specified you can