I had a hard time finding a complete guide for OS X so I decided to write one.
Open your terminal and update Brew using brew doctor command.
Install steem dependecies using this command.
brew install boost cmake git openssl autoconf automake qt5
Create a symling for openssl using this command brew link --force openssl
Install berkeley-db and google-preftools
brew install google-perftools
brew install berkeley-db
brew install libtool
brew install python3
git clone https://github.com/steemit/steem.gitcd steem git submodule update --init --recursive
cmake .
make
If you receive this message [100%] Built target chain_test it means that you are good to go !
Enjoy !