Can you use debuild to only apply patches to source and then exit?

I am trying to build gcc-6 source package on Raspbian stretch; so I do:

apt source gcc-6
cd gcc-6-6.3.0/debian
debuild -b -uc -us

The debuild command starts the full build. Since the build crashes on my platform, what I'd like to run a command, that will unpack the sources and apply the Debian patches, but then stop before configuring (so I can apply my own patches) - and then I could continue afterwards with debuild -b -uc -us -nc. Is there a command that would help me do that?