diff --git a/share/mk/bsd.README b/share/mk/bsd.README
index ffbe8257dbd..89e7f1ca704 100644
--- a/share/mk/bsd.README
+++ b/share/mk/bsd.README
@@ -336,6 +336,13 @@ with the current needs of the BSD tree.
 
 It sets/uses the following variables:
 
+LIB		The name of the library to build.
+
+LIB_CXX		The name of the library to build. It also causes
+		<bsd.lib.mk> to link the library with the
+		standard C++ library.  LIB_CXX overrides the value
+		of LIB if LIB is also set.
+
 LIBDIR		Target directory for libraries.
 
 LINTLIBDIR	Target directory for lint libraries.