[Cygwin] possible OCAML bug on 'make install'

I am getting the following on doing a ‘make install’ on Cygwin platform :-

llvm[1]: Packaging HTML documentation
llvm[1]: Installing HTML documentation
llvm[1]: Building ocamldoc documentation
make[2]: Entering directory /home/ang/build/llvm/bindings/ocaml' make[2]: *** No rule to make target ocamldoc’. Stop.
make[2]: Leaving directory /home/ang/build/llvm/bindings/ocaml' make[1]: *** [regen-ocamldoc] Error 2 make[1]: Leaving directory /home/ang/build/llvm/docs’
make: *** [install] Error 1