MacPorts supports arm-elf-gcc.
$ port search arm-elf
arm-elf-binutils @ 2.20.51.0.2 (cross, devel)
FSF binutils for arm-elf cross development
arm-elf-gcc @ 4.3.2 (cross, devel)
gcc cross-compilers for arm-elf, with newlib runtime library.
arm-elf-gcc3 @ 3.4.6 (cross, devel)
gcc 3.x cross-compilers for arm-elf, with newlib runtime library.
Found 3 ports.
After installing MacPorts, all you need is:
$ sudo port install arm-elf-gcc
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