First try AR, then try LIBTOOL...

Makefile

@@ -105,7 +105,11 @@ lib:
 	mkdir lib
 
 lib/$(LIB.STATIC): $(LIB.OBJS)
+ifneq ($(AR),)
 	$(AR) $(ARFLAGS) $@ $^
+else ifneq ($(LIBTOOL),)
+	$(LIBTOOL) $@ $^
+endif
 ifneq ($(STRIP),)
 	$(STRIP) -x $@
 endif
@@ -149,7 +153,14 @@ glew.pc: glew.pc.in
 glew.lib.mx:  lib lib/$(LIB.SHARED.MX) lib/$(LIB.STATIC.MX) glewmx.pc
 
 lib/$(LIB.STATIC.MX): $(LIB.OBJS.MX)
+ifneq ($(AR),)
 	$(AR) $(ARFLAGS) $@ $^
+else ifneq ($(LIBTOOL),)
+	$(LIBTOOL) $@ $^
+endif
+ifneq ($(STRIP),)
+	$(STRIP) -x $@
+endif
 
 lib/$(LIB.SHARED.MX): $(LIB.SOBJS.MX)
 	$(LD) $(LDFLAGS.SO.MX) -o $@ $^ $(LIB.LDFLAGS) $(LIB.LIBS)

config/Makefile.darwin-universal

 NAME = $(GLEW_NAME)
 CC = cc
 LD = cc
-AR = LIBTOOL
-ARFLAGS = -static -o
+AR = 
+LIBTOOL = libtool -static -o
 STRIP = 
 CFLAGS.EXTRA = -dynamic -fno-common
 #CFLAGS.EXTRA += -no-cpp-precomp