An update from the one I wrote years ago. That one overrides entire CFLAGS and thus missing -O3 and all those good optimization stuff.

In short, do this first:

export cflags="-I/usr/local/include"
export LDFLAGS="-L/usr/local/lib"

And then build as usual: ./configure --prefix=... && make ....

I usually put that block of config in a script called _build:

#!/bin/sh

<the export lines above>

exec "$@"

To use it just prefix the build commands with it: _build ./configure ... && _build ....