How to prevent libtool to add system path (i.e. /usr/lib) to RUNPATH (rpath)?

How to prevent libtool to add system path (i.e. /usr/lib) to RUNPATH (rpath)?

During testing (checking) MPFR libtool adds system path to rpath before testing path, i.e.:

0x000000000000001d (RUNPATH) Library runpath: [/usr/lib:/LFSC/native/src/bmpfr/src/.libs]

As a result, tests can run installed libs (in the first path (system)) instead of testing ones. This happens usually when reinstalling software. Maybe this affects installing of upgrades.

This is because of existing dependency’s .la file, e.g. libquadmath.la

Removing .la files resolves this problem.

But there is no reason at all to add system path into hardcoded RUNPATH.

Is there any way to resolve this problem without deleting .la files?