XML::LibXML install: /usr/bin/ld: cannot find -lxml2

After fighting with it for a couple hours yesterday, I was not able to
install the Perl module XML::LibXML.  libxml2.so.2 is in /usr/lib but
cc/ld can't find it even with a "-L/usr/lib" directive.

The problem is here:

LD_RUN_PATH="" cc  -shared -L/usr/local/lib Conftest.o  -o blib/arch/auto/Conftest/Conftest.so   -lxml2 -lz -lm

During the make invocation I specified "LIBS='-L/usr/lib", so I don't
understand why it uses '-L/usr/local/lib' here, but I didn't bother to
track this problem down.  Instead I ran the correct command manually

LD_RUN_PATH="" cc  -shared -L/usr/lib Conftest.o  -o blib/arch/auto/Conftest/Conftest.so   -lxml2 -lz -lm

*Both* versions fail with

/usr/bin/ld: cannot find -lxml2
collect2: ld returned 1 exit status

This makes no sense to me.  libxml2.so.2 is right there in /usr/lib.

Any ideas?

Thanks,

kj