How to use a combined gcc/binutils/newlibc source tree to create a cross compiler:

Download into a empty directory (${HOME}/tarballs)
binutils - http://gnuftp.uib.no/binutils
gcc - http://gnuftp.uib.no/gcc/
gmp (dependency for gcc) - http://gnuftp.uib.no/gmp/
mpfr (dependency for gcc) - http://gnuftp.uib.no/mpfr/
mpc (dependency for gcc) - http://gnuftp.uib.no/mpc/
isl (OPTIONAL dependency for gcc) http://isl.gforge.inria.fr/


Create yet another directory, enter it and unpack
$ mkdir ${HOME}/src; cd ${HOME}/src
$ for i in ${HOME}/tarballs/*; do tar xf $i; done

Create combined source tree
cd gcc-*
ln -s ../gmp-* gmp
ln -s ../mpfr-* mpfr
ln -s ../mpc-* mpc
ln -s ../isl-* isl

$ for i in bfd binutils gas gold ld opcodes; do ln -s ../binutils-*/$i; done

Build the compiler

mkdir ${HOME}/obj; cd ${HOME}/obj
${HOME}/src/gcc-*/configure --prefix=/tools --libexecdir=/tools/lib --enable-languages=c,c++ --disable-libstdcxx-pch --disable-multilib --enable-checking=release --with-tune=native --with-arch=native

(optional: fix compiler flags)
sed -i 's/\-g /-pipe /' Makefile
sed -i '/^CFLAGS/s/$/ -march=native -mtune=native/' Makefile
sed -i '/^CXXFLAGS/s/$/ -march=native -mtune=native/' Makefile

Compile and install into staging area
make -j$(nproc) tooldir=/tools
mkdir -p dest/tools/lib 
ln -sf lib dest/tools/lib64
make -j2 install-strip DESTDIR=$(pwd)/dest tooldir=/tools

Do some trimming

rm -rf dest/*/share
find dest -name '*.la' -delete
find dest -name "*.a" -exec ./dest/*/bin/strip -g "{}" \;