Compiling and linking programs

[chuck noyes]

I'm trying to compile and link gnuplot and I consistently receive the
following error:

/usr/i486-linux/bin/ld: cannot open -lX11: No such file or directory

I think the loader is complaining about not being able to find libX11.a.
Is this right?  Is there a way around this, maybe by specifting a
different library?

I'm running slackware96 with a 2.0.24 ELF kernel.

                            Thanks,
                                    Chuck