Installation on Amazon Linux fails

Spun up a new Amazon instance, selecting the AMI specified in the installation instructions (specifically AMI ID amzn-ami-hvm-2018.03.0.20180622-x86_64-gp2 (ami-cfe4b2b0)). Was able to follow instructions up to the command:

> cmake3 .. -DCMAKE_INSTALL_PREFIX=/usr

which appeared to be successful until this output:

> -- Found FLEX: /usr/bin/flex (found version "2.5.37")
> CMake Error at CMakeLists.txt:29 (find_package):
> Could not find a package configuration file provided by "LLVM" with any of
> the following names:
>
> LLVMConfig.cmake
> llvm-config.cmake
>
> Add the installation prefix of "LLVM" to CMAKE_PREFIX_PATH or set
> "LLVM_DIR" to a directory containing one of the above files. If "LLVM"
> provides a separate development package or SDK, be sure it has been
> installed.
>
>
> -- Configuring incomplete, errors occurred!
>