-Os -> libXaw.so: undefined reference to `.L91'

Cross-posted because the failure happens when compiling teTex even 
though the problem is really caused by (XFree86|xorg)-libraries. 
Ignorant folks (like me) may not know to do a "pkg_which 
/usr/X11R6/lib/libXaw.so" and ask on the -x11 list.  Also, this shows 
that -Os may not be as reliable as expected.  I apologize if I shouldn't 
have cross-posted.

Short version:
Don't compile (XFree86|xorg)-libraries with -Os.

Long, rambling version:
I have been running into the following problem when attempting to 
compile teTex:
/usr/X11R6/lib/libXaw.so: undefined reference to `.L91'

A search turned up this page (not sure on the language -- all I know is 
that I can't read it!):
http://www.bsdguru.org/dyskusja/viewtopic.php?t=2707

My deductive reasoning skills noted the following details about the 
final post:
1) smiley face (with shades!), usually indicative of a problem solved
2) -Os, a flag I have in /etc/make.conf
3) "bibliotek XFree", which I assume is XFree86-libraries (go high 
school Spanish!)

I recompiled the xorg-libraries port with just -O (instead of -Os) and, 
violà, everything compiles nicely.  In retrospect, it was a simple 
library problem and I should have known to recompile 
(XFree86|xorg)-libraries based on the origin of libXaw.so.

Anyone run into problems with -Os on other ports?  I've seen some ports 
not compile with it (mplayer is the only that immediately comes to 
mind), but never a delayed issue like this where it affects a different 
port.

Jon Noack