passing -R to libtool

[deckrider]

I'm using:

automake (GNU automake) 1.10
autoconf (GNU Autoconf) 2.61
ltmain.sh (GNU libtool) 1.5.22 (1.1220.2.365 2005/12/18 22:14:06)

Given that I don't know where a user has installed prerequisite
libraries, I assume the user can pass their location using LDFLAGS.
For instance:

./configure LDFLAGS="-L/my/path/to/the/lib"

However, for each of these -L in LDFLAGS, I think I would like to have
a corresponding -R sent to libtool.  Is this correct?  What is the
best practice for this? Does the user decide to give -R, and if so,
what variable, and should I use AC_ARG_VAR() for it?

Thanks,
Dave.