Cannot link boost libraries with CMake

I have a sample C++ code that uses boost (program options module) as shown below:

#include <iostream>

#include <boost/program_options/options_description.hpp>
#include <boost/program_options/parsers.hpp>
#include <boost/program_options/variables_map.hpp>

namespace po = boost::program_options;

int main(int argc, const char* argv[]){
    po::options_description description("MyTool Usage");

    description.add_options()
        ("help,h", "Display this help message")
        ("version,v", "Display the version number");

    po::positional_options_description p;

    po::variables_map vm;
    po::store(po::command_line_parser(argc, argv).options(description).positional(p).run(), vm);
    po::notify(vm);

    if(vm.count("help")){
        std::cout << description;

        return 0;
    }

    if(vm.count("version")){
        std::cout << "MyTool Version 1.0" << std::endl;

        return 0;
    }

    return 0;
}

I tried to compile using cmake. The corresponding CMakeLists.txt file is shown below:

cmake_minimum_required(VERSION 2.6)

set(CMAKE_CXX_LINK_FLAGS "-std=c++11 -g -Wall -fsigned-char -lboost_program_options-mt")

set(BOOST_ROOT /opt/local/include/boost)
set(BOOST_LIBRARYDIR /opt/local/lib)
find_package(Boost COMPONENTS program_options system filesystem REQUIRED)
include_directories(${BOOST_INCLUDE_DIR})
link_libraries(${BOOST_LIBRARIES})

add_executable(testboostpo testboostpo_simple.cpp)
target_link_libraries(testboostpo ${Boost_LIBRARIES})

Although cmake . seems to succeed and it also detects all the boost modules I typically use (program options, system, filesystem),

$ cmake .
-- The C compiler identification is GNU 5.5.0
-- The CXX compiler identification is GNU 5.5.0
-- Checking whether C compiler has -isysroot
-- Checking whether C compiler has -isysroot - yes
-- Checking whether C compiler supports OSX deployment target flag
-- Checking whether C compiler supports OSX deployment target flag - yes
-- Check for working C compiler: /opt/local/bin/gcc-mp-5
-- Check for working C compiler: /opt/local/bin/gcc-mp-5 -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Checking whether CXX compiler has -isysroot
-- Checking whether CXX compiler has -isysroot - yes
-- Checking whether CXX compiler supports OSX deployment target flag
-- Checking whether CXX compiler supports OSX deployment target flag - yes
-- Check for working CXX compiler: /opt/local/bin/g++-mp-5
-- Check for working CXX compiler: /opt/local/bin/g++-mp-5 -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Boost version: 1.66.0
-- Found the following Boost libraries:
--   program_options
--   system
--   filesystem
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/params/libraries/coding_interview/every_test/boost_test

the next step make fails with the following error: $ make

Scanning dependencies of target testboostpo
[ 50%] Building CXX object CMakeFiles/testboostpo.dir/testboostpo_simple.cpp.o
[100%] Linking CXX executable testboostpo
ld: library not found for -lboost_program_options-mt
collect2: error: ld returned 1 exit status
make[2]: *** [testboostpo] Error 1
make[1]: *** [CMakeFiles/testboostpo.dir/all] Error 2
make: *** [all] Error 2

There seems to be a problem linking boost library for program options. However, I can see that the library is installed at /opt/local/lib/libboost_program_options-mt.dylib

Alternatively, I also tried isolating the compilation but it fails as well.

$ g++ -L/opt/local/lib testboostpo_simple.cpp -lboost_program_options-mt
Undefined symbols for architecture x86_64:
  "boost::program_options::to_internal(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
      std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > boost::program_options::to_internal<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&) in ccg8tggM.o
  ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status

$ g++ -L/opt/local/lib testboostpo_simple.cpp /opt/local/lib/libboost_program_options-mt.dylib
Undefined symbols for architecture x86_64:
  "boost::program_options::to_internal(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
      std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > boost::program_options::to_internal<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&) in ccg8tggM.o
  ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status

I am using gcc5, boost 1.66 and cmake 3.12 (all of them installed using macports). boost header files are in location: /opt/local/include/boost/ and the boost library files are in location: /opt/local/lib

Does anybody here know what might be causing the boost linking to still fail despite providing the paths? Anything else missing here or incorrectly specified?

Thanks,