libvpx: failes with unknown argument: '-fno-integrated-as' on Yosemite

[skymoo (Adam Mercer)]

I'm setting up a new iMac, running Mac OS X 10.10.1 and Xcode-6.1.1 and the build is failing with the following:

:info:build make: Entering directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_multimedia_libvpx/libvpx/work/libvpx-v1.3.0'
:info:build /usr/bin/clang -S -pipe -Os -arch x86_64 -m64 -arch x86_64 -O3 -fPIC -Wall -Wdeclaration-after-statement -Wdisabled-optimization -Wpointer-arith -Wtype-limits -Wcast-qual -Wvla -Wimplicit-function-declaration -Wuninitialized -Wunused-variable -fno-strict-aliasing -Wno-unused-function -I. -I"/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_multimedia_libvpx/libvpx/work/libvpx-v1.3.0" -DINLINE_ASM -fno-integrated-as -o vp8/encoder/vp8_asm_enc_offsets.c.S vp8/encoder/vp8_asm_enc_offsets.c
:info:build clang: error: unknown argument: '-fno-integrated-as'

My clang is:

$ clang --version
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.0.0
Thread model: posix
$

A full build log is attached.