--- a/make/autoconf/spec.gmk.in	Thu Nov 30 11:19:14 2017 -0800
+++ b/make/autoconf/spec.gmk.in	Thu Nov 30 13:29:50 2017 -0800
@@ -471,6 +471,7 @@
 STRIP:=@STRIP@
 
 LIPO:=@LIPO@
+INSTALL_NAME_TOOL:=@INSTALL_NAME_TOOL@
 
 # Options to linker to specify a mapfile.
 # (Note absence of := assignment, because we do not want to evaluate the macro body here)