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+Building Python with Emscripten
+===============================
+
+These directions should work for Python 2.7.x (last tested with 2.7.5).
+
+First, uncompress Python into two separate directories, one for native
+and one for JavaScript.
+
+In the JavaScript directory, do:
+
+````
+    EMCONFIGURE_JS=1 emconfigure ./configure --without-threads --without-pymalloc --enable-shared --disable-ipv6
+````
+
+If you are on Mac OS X, you will also want ``disable-toolbox-glue``.
+If you are on an older version of Python (such as 2.7.2), you may
+not need the ``--disable-ipv6`` option.
+
+If you are on Python 2.7.4 or later, you will need to edit the
+``Makefile`` generated and remove the ``MULTIARCH=`` line(s).
+You will also need to edit ``pyconfig.h`` and remove defines
+for ``DOUBLE_IS_BIG_ENDIAN_IEEE754``, ``DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754``,
+and ``HAVE_GCC_ASM_FOR_X87``.
+
+On Python 2.7.2, you will need to edit ``pyconfig.h`` and remove
+``HAVE_GCC_ASM_FOR_X87``, ``HAVE_SIG*`` except for ``SIGNAL_H``
+and *add* ``#define PY_NO_SHORT_FLOAT_REPR``.
+
+Now, you can run ``make``. It will fail trying to run ``pgen``.
+
+At this point, go to your native directory and run:
+
+````
+./configure --without-threads --without-pymalloc --enable-shared --disable-ipv6
+````
+
+Now, run ``make`` in the native directory and then copy the generated ``Parser/pgen``
+to your JavaScript directory. Back in your JavaScript directory, be sure to flag
+the ``pgen`` executable as executable:
+
+````
+chmod +x Parser/pgen
+````
+
+Now, run ``make`` again.
+
+You will get an error about trying to run ``python`` or ``python.exe``. This
+can be ignored.
+
+Now, you can link the bitcode file that you need:
+
+````
+llvm-link libpython2.7.so Modules/python.o -o python.bc
+````
+
+If you are on Mac OS X, you will want to look for ``libpython2.7.dylib``
+instead of ``libpython2.7.so``.
+
+Thanks to rasjidw and everyone else who has helped with this!