philip@debian:~/src/kaleidoscope-ocaml$ ls
ast.ml  _build  codegen.ml  lexer.ml  myocamlbuild.ml  parser.ml  _tags  _tags~  token.ml  toplevel.ml  toy.byte  toy.ml  toy.native
philip@debian:~/src/kaleidoscope-ocaml$ cat _tags
<{lexer,parser}.ml>: use_camlp4, pp(camlp4of)
<*.{byte,native}>: g++, use_llvm, use_llvm_analysis

philip@debian:~/src/kaleidoscope-ocaml$ cat myocamlbuild.ml
open Ocamlbuild_plugin;;

ocaml_lib ~extern:true "llvm";;
ocaml_lib ~extern:true "llvm_analysis";;

flag ["link"; "ocaml"; "g++"] (S[A"-cc"; A"g++"]);;
philip@debian:~/src/kaleidoscope-ocaml$