Current Version: cctools: 921, ld64: 409.12.
Originally ported by cjacker.

SUPPORTED OPERATING SYSTEMS:

Linux, FreeBSD, Mac OS X and iOS

Other BSDs may or may not work.

SUPPORTED HOST ARCHITECTURES:

x86, x86_64, arm

Untested, but compiles:

aarch64, ppc, ppc64

armv6, armv7, armv7s, arm64, i386, x86_64,
x86_64h, armv6m, armv7k, armv7m and armv7em

Mac OS X, iOS, watchOS (untested) and tvOS (untested)

Clang 3.4+

SDKs with .tdb stubs (>= Xcode 7) require the TAPI library to be installed.
=> https://github.com/tpoechtrager/apple-libtapi

musl-libc based systems require the musl-fts library to be installed. => https://github.com/pullmoll/musl-fts

Optional, but recommended:

llvm-devel (For Link Time Optimization Support)
uuid-devel (For ld64 -random_uuid Support)
llvm-devel + xar-devel (For ld64 -bitcode_bundle Support)

You can find xar here.
Do not install libxar-dev on Ubuntu, it's a different package.

This step is only required if you intend to use SDKs with .tdb stubs.

git clone https://github.com/tpoechtrager/apple-libtapi.git
cd apple-libtapi
[INSTALLPREFIX=/home/user/cctools] ./build.sh
./install.sh

git clone https://github.com/tpoechtrager/cctools-port.git
cd cctools-port/cctools
./configure \
    [--prefix=/home/user/cctools] \
    [--with-libtapi=/home/user/cctools] \
    [--target=<target>] \
    [--with-llvm-config=...]
make
make install

target = i386-apple-darwin11, x86_64-apple-darwin11, arm-apple-darwin11, ...

If you get compile errors because of unistd.h, then please run
../tools/fix_unistd_issue.sh and restart compiling.