diff --git a/lldb/test/make/Makefile.rules b/lldb/test/make/Makefile.rules
index 80cb409842a134d85ba7b212ffbc5a2936c0382c..75f99900af3ecb17b10960b98cf873fe000b0414 100644
--- a/lldb/test/make/Makefile.rules
+++ b/lldb/test/make/Makefile.rules
@@ -6,6 +6,12 @@
 # OBJC_SOURCES :=
 # OBJCXX_SOURCES :=
 # DYLIB_C_SOURCES :=
+# DYLIB_CXX_SOURCES :=
+#
+# Specifying DYLIB_ONLY has the effect of building dylib only, skipping
+# the building of the a.out executable program.  For example,
+# DYLIB_ONLY := YES
+#
 
 # Uncomment line below for debugging shell commands
 # SHELL = /bin/sh -x