sudo add-apt-repository ppa:ubuntu-toolchain-r/test

sudo apt-get update

sudo apt-get install gcc-4.9

sudo apt-get upgrade libstdc++6

After this is complete, make sure to run the following:
sudo apt-get dist-upgrade

Also, make sure to confirm the necessary dependencies are installed for the right GLIBCXX version.
strings /usr/lib/x86_64-linux-gnu/libstdc++.so.6 | grep GLIBCXX