One-click static-friendly musl-based GCC OS X-to-Linux cross-compilers.
brew install FiloSottile/musl-cross/musl-cross
By default it will build a full cross compiler toolchain targeting musl Linux amd64 using richfelker/musl-cross-make.
(It takes a while, getting a cup of coffee won't do. Going for a run might if you are more fit than me.)
You can then use x86_64-linux-musl- versions of the tools to build for the target.
For example x86_64-linux-musl-cc will compile C code to run on musl Linux amd64.
The "musl" part of the target is important: the binaries will ONLY run on a musl-based system, like Alpine.
However, if you build them as static binaries by passing -static as a LDFLAG they will run anywhere.
Musl is specifically engineered to support static binaries.
Other architectures are supported. For example to get a Raspberry Pi cross-compiler use:
brew install FiloSottile/musl-cross/musl-cross --without-x86_64 --with-arm-hf
You can also use --with-i486 (x86 32-bit) and --with-arm (ARM soft-float).
Only tested on El Capitan.