Assuming you have the AWS CLI installed, and if you are using Amazon Linux, it is installed by default, this is how you can copy a directory to S3 with public read permissions set.
aws s3 cp build s3://blog.brng.us/ --recursive --grants read=uri=http://acs.amazonaws.com/groups/global/AllUsers
About this blog: This blog will discuss technology associated with my idgon.com project. I am using Elixir and Phoenix for my backend, and React.js and Reflux for my front end. I have a library called Trabant to experiment with graph database persistence for Elixir. The views expressed on this blog are my own, and are not that of my current employer.