"make install-strip" should work
With the bindists (not sure about a normal build tree) install-strip doesn't work:
$ make install-strip make: *** No rule to make target `install-strip'. Stop. $
It is defined in mk/install.mk, so it presumably is meant to. The blurb after running configure should mention it, too.
The target is described in the GNU coding standards: http://www.gnu.org/prep/standards/html_node/Standard-Targets.html