My machine is a Mac with OS X El Capitan installed.

Using Homebrew I have installed openssl 1.0.2h_1 but it does not allow it to be linked to usr/local.

openssl version -a returns:

OpenSSL 0.9.8zh 14 Jan 2016
built on: Feb  4 2016
platform: darwin64-x86_64-llvm
options:  bn(64,64) md2(int) rc4(ptr,char) des(idx,cisc,16,int) blowfish(idx)
compiler: -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -fasm-blocks -O3 -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -DL_ENDIAN -DMD32_REG_T=int -DOPENSSL_NO_IDEA -DOPENSSL_PIC -DOPENSSL_THREADS -DZLIB -mmacosx-version-min=10.6
OPENSSLDIR: "/System/Library/OpenSSL"

which openssl returns /usr/bin/openssl.

I want to build Boost but I understand from the answer posted to this question that Boost will use the openssl version provided by the system.

How do I force the boost build to use the version of openssl I have installed via Homebrew?