--- old/make/aix/makefiles/xlc.make	2015-11-04 23:02:14.591385472 -0500
+++ new/make/aix/makefiles/xlc.make	2015-11-04 23:02:12.743281320 -0500
@@ -74,6 +74,9 @@
 CFLAGS += -qnortti
 CFLAGS += -qnoeh
 
+# for compiler-level tls
+CFLAGS += -qtls=default
+
 CFLAGS += -D_REENTRANT
 # no xlc counterpart for -fcheck-new
 # CFLAGS += -fcheck-new