diff --git a/build b/build
new file mode 100755
index 0000000..cbb4236
--- /dev/null
+++ b/build
@@ -0,0 +1,219 @@
+#!/bin/bash
+
+################################################################################
+#                                    Config                                    #
+################################################################################
+
+# Whether to produce optimized, name-mangled, debugging-unfriendly JS.
+OPTIMIZED=0
+
+# Which functions to export to the final Module object.
+EXPORTS='["_main","_PyRun_SimpleStringFlags"]'
+
+# Where the LLVM binaries can be found.
+LLVM=/home/max/emscripten-workspace/llvm-build/Release/bin/
+
+# Which modules to build dynamically.
+# Maps each module name to the C files implementing it.
+declare -A MODULES
+MODULES[array]="arraymodule.c"
+MODULES[cmath]="cmathmodule.c _math.c"
+MODULES[math]="mathmodule.c _math.c"
+MODULES[strop]="stropmodule.c"
+MODULES[time]="timemodule.c"
+MODULES[datetime]="datetimemodule.c timemodule.c"
+MODULES[itertools]="itertoolsmodule.c"
+MODULES[future_builtins]="future_builtins.c"
+MODULES[_random]="_randommodule.c"
+MODULES[_collections]="_collectionsmodule.c"
+MODULES[_bisect]="_bisectmodule.c"
+MODULES[_heapq]="_heapqmodule.c"
+MODULES[operator]="operator.c"
+MODULES[_functools]="_functoolsmodule.c"
+MODULES[_io]="_io/bufferedio.c _io/bytesio.c _io/fileio.c _io/iobase.c _io/_iomodule.c _io/stringio.c _io/textio.c"
+MODULES[_json]="_json.c"
+MODULES[_testcapi]="_testcapimodule.c"
+MODULES[_hotshot]="_hotshot.c"
+MODULES[_lsprof]="_lsprof.c rotatingtree.c"
+MODULES[unicodedata]="unicodedata.c"
+MODULES[_locale]="_localemodule.c"
+MODULES[fcntl]="fcntlmodule.c"
+MODULES[grp]="grpmodule.c"
+MODULES[spwd]="spwdmodule.c"
+MODULES[cStringIO]="cStringIO.c"
+MODULES[cPickle]="cPickle.c"
+MODULES[mmap]="mmapmodule.c"
+MODULES[syslog]="syslogmodule.c"
+MODULES[audioop]="audioop.c"
+MODULES[imageop]="imageop.c"
+MODULES[crypt]="cryptmodule.c"
+MODULES[_csv]="_csv.c"
+MODULES[_socket]="socketmodule.c"
+MODULES[_sha]="shamodule.c"
+MODULES[_md5]="md5module.c md5.c"
+MODULES[_sha256]="sha256module.c"
+MODULES[_sha512]="sha512module.c"
+MODULES[gdbm]="gdbmmodule.c"
+MODULES[termios]="termios.c"
+MODULES[resource]="resource.c"
+MODULES[nis]="nismodule.c"
+MODULES[_curses]="_cursesmodule.c"
+MODULES[_curses_panel]="_curses_panel.c"
+MODULES[zlib]="zlibmodule.c"
+MODULES[binascii]="binascii.c"
+MODULES[bz2]="bz2module.c"
+MODULES[_elementtree]="_elementtree.c"
+MODULES[_multibytecodec]="cjkcodecs/multibytecodec.c"
+MODULES[_codecs_kr]="cjkcodecs/_codecs_kr.c"
+MODULES[_codecs_jp]="cjkcodecs/_codecs_jp.c"
+MODULES[_codecs_cn]="cjkcodecs/_codecs_cn.c"
+MODULES[_codecs_tw]="cjkcodecs/_codecs_tw.c"
+MODULES[_codecs_hk]="cjkcodecs/_codecs_hk.c"
+MODULES[_codecs_iso2022]="cjkcodecs/_codecs_iso2022.c"
+MODULES[dl]="dlmodule.c"
+MODULES[pyexpat]="pyexpat.c expat/xmlparse.c expat/xmlrole.c expat/xmltok.c"
+MODULES[parser]="parsermodule.c"
+MODULES[_struct]="_struct.c"
+
+# These are baked into the main executable but can also be built separately.
+# MODULES[_symtable]="symtablemodule.c"
+# MODULES[zipimport]="zipimport.c"
+
+# These are disabled because they contain inline assembly.
+# MODULES[fpectl]="fpectlmodule.c"
+# MODULES[select]="selectmodule.c"
+# MODULES[linuxaudiodev]="linuxaudiodev.c"
+# MODULES[ossaudiodev]="ossaudiodev.c"
+
+################################################################################
+#                                    Script                                    #
+################################################################################
+
+# TODO: Make it possible to build only the main python.js, only modules or only
+#       a specific module.
+# TODO: Build the native version too, for comparison during debugging.
+
+# Exit on first error.
+set -e
+
+# Setup optimization flags for all future emscripting.
+if [ $OPTIMIZED -eq 1 ]; then
+  OPTIMIZATION_ARGS="-s OPTIMIZE=1 -s RELOOP=1 -s ASSERTIONS=0"
+else
+  OPTIMIZATION_ARGS="-s OPTIMIZE=0 -s RELOOP=0 -s ASSERTIONS=1"
+fi
+
+# Create two folders for intermediate and final files, respectively.
+mkdir -p obj
+mkdir -p dist
+
+# Remove old build.
+rm -rf obj/*
+rm -rf dist/*
+
+# Start building in the obj folder.
+cd obj
+
+# Create the Makefile and configurations using a filtering proxy for llvm-gcc.
+CC=../ccproxy.py ../cpython/configure --without-threads --without-pymalloc
+
+# Adjust configuration.
+# Remove the closing endif so we can insert new options.
+sed -i 's~#endif /\*Py_PYCONFIG_H\*/~~' pyconfig.h
+# Emscripten doesn't support CPU-specific assembly code.
+echo '#undef HAVE_GCC_ASM_FOR_X87' >> pyconfig.h
+# Emscripten does not support interrupt signals.
+echo '#undef HAVE_SIGACTION' >> pyconfig.h
+echo '#undef HAVE_SIGINTERRUPT' >> pyconfig.h
+echo '#undef HAVE_SIGRELSE' >> pyconfig.h
+# Put the closing endif back.
+echo '#endif /*Py_PYCONFIG_H*/' >> pyconfig.h
+
+# Compile CPython.
+echo 'Compiling...'
+make
+
+# Link the resulting libraries.
+echo 'Relinking...'
+mkdir -p relinked
+cd relinked
+ar x ../libpython2.7.a
+cp ../Modules/python.o .
+${LLVM}/llvm-link -o=python.bc *.o
+cp python.bc ..
+cd ..
+
+# Run LLVM optimizations.
+if [ $OPTIMIZED -eq 1 ]; then
+  echo 'Running LLVM optimizations...'
+  ${LLVM}/opt -O3 -o python.opt.bc python.bc
+else
+  cp python.bc python.opt.bc
+fi
+
+# Compile the assembly into JS using Emscripten.
+echo 'Emscripting...'
+# TODO: Add -m/--dlmalloc once it's debugged.
+python2 ../emscripten/emscripten.py python.opt.bc -o python.js \
+    -s INCLUDE_FULL_LIBRARY=1 -s EXPORTED_FUNCTIONS=$EXPORTS \
+    $OPTIMIZATION_ARGS
+
+# Copy the main Python JS executable to dist.
+cp python.js ../dist/python.js
+
+# Copy the pure Python modules to dist.
+# TODO: Remove unnecessary files and folders.
+cp -r ../cpython/Lib/* ../dist
+
+# Create a dummy modules list.
+mkdir -p ../dist/Modules
+touch ../dist/Modules/Setup
+
+# Build dynamically loaded modules.
+echo 'Building dynamic modules...'
+function build_module {
+  echo "Building $1..."
+
+  # Compile.
+  FLAGS="-c -emit-llvm -fPIC -fno-strict-aliasing -I. -IInclude -I../cpython/Include -Wstrict-prototypes"
+  FILES=""
+  for ((i=2; i<=$#; i++)); do
+    ../ccproxy.py $FLAGS ../cpython/Modules/${!i} -o `basename ${!i}`.o
+    FILES="$FILES `basename ${!i}`.o"
+  done
+
+  # Link.
+  ../ccproxy.py $FILES -o $1.so.bc
+
+  # Optimize.
+  if [ $OPTIMIZED -eq 1 ]; then
+    ${LLVM}/opt -O3 -o $1.so.opt.bc $1.so.bc
+  else
+    cp $1.so.bc $1.so.opt.bc
+  fi
+
+  # Emscript.
+  python2 ../emscripten/emscripten.py $1.so.opt.bc -o $1.so.js \
+      -s BUILD_AS_SHARED_LIB=1 -s EXPORTED_FUNCTIONS="[\"_init$1\"]" \
+      $OPTIMIZATION_ARGS
+
+  # Copy the new module to dist.
+  cp $1.so.js ../dist/$1.so.js
+}
+for i in "${!MODULES[@]}"; do
+  build_module $i ${MODULES[$i]}
+done
+
+# Create virtual file system entries.
+echo 'Mapping virtual filesystem.'
+python2 ../map_filesystem.py ../dist ../dist/python.js
+
+# TODO: Optimize and compress the resulting JS using Closure.
+#       Below is an old version that doesn't work right now.
+# if [ $OPTIMIZED -eq 1 ]; then
+#   echo 'Running closure...'
+#   closure --compilation_level ADVANCED_OPTIMIZATIONS --variable_map_output_file python.js.vars --js python.js --js_output_file python.opt.js
+# else
+#   cp ../dist/python.js ../dist/python.opt.js
+#   touch ../dist/python.js.vars
+# fi
diff --git a/ccproxy.py b/ccproxy.py
new file mode 100755
index 0000000..f2d8407
--- /dev/null
+++ b/ccproxy.py
@@ -0,0 +1,101 @@
+#!/usr/bin/env python2
+
+from __future__ import with_statement
+
+import os
+import subprocess
+import shutil
+import sys
+
+# LLVM commands.
+# TODO: Factor out to be configurable from ./build.
+CC = '/home/max/emscripten-workspace/llvm-gcc-install/bin/llvm-gcc'
+LINK = '/home/max/emscripten-workspace/llvm-build/Release/bin/llvm-link'
+LLC = '/home/max/emscripten-workspace/llvm-build/Release/bin/llc'
+
+# Argument filters.
+SKIPPED_CC_ARGS = [
+  # Don't run optimizations prematurely.
+  '-O1',
+  '-O2',
+  '-O3',
+]
+ADDITIONAL_CC_ARGS = [
+  # Compile for the most basic posible x86 machine.
+  '-m32',
+  # Compile with debugging info, so emscripten can easily access struct members.
+  '-g',
+  # Avoid architecture-specific optimizations.
+  '-U__i386__',
+  '-U__x86_64__',
+  '-U__SSE__',
+  # Our doubles are funky. Don't rely on accuracy.
+  '-UX87_DOUBLE_ROUNDING',
+  # We can't run inline assembly.
+  '-UHAVE_GCC_ASM_FOR_X87',
+  # Use plain old utime() instead of utimes().
+  '-UHAVE_UTIMES',
+  # Tell expat we actually have MEMMOVE, despite its belief in the opposite.
+  '-DHAVE_MEMMOVE',
+  # Tell elementtree that we have expat available.
+  '-DUSE_PYEXPAT_CAPI',
+]
+ALLOWED_LINK_ARGS = [
+  # Don't allow linking to external libraries.
+  '-f',
+  '-help',
+  '-o',
+  '-print-after',
+  '-print-after-all',
+  '-print-before',
+  '-print-before-all',
+  '-time-passes',
+  '-v',
+  '-verify-dom-info',
+  '-version',
+]
+
+# Determine whether we want to call the linker or the compiler.
+call = LINK
+for arg in sys.argv[1:]:
+  if arg ==  '--version' or (not arg.startswith('-') and arg.endswith('.c')):
+    call = CC
+    break
+
+# Filter the args.
+if call == CC:
+  newargs = [arg for arg in sys.argv[1:] if arg not in SKIPPED_CC_ARGS]
+  newargs += ADDITIONAL_CC_ARGS
+  if 'conftest.c' not in newargs:
+    # For real files (rather than tests), we want to compile to LLVM bytecode.
+    newargs.append('-emit-llvm')
+    newargs.append('-c') 
+else:
+  def isArgAllowed(arg):
+    return not arg.startswith('-') or arg.split('=')[0] in ALLOWED_LINK_ARGS
+  newargs = [arg for arg in sys.argv[1:] if isArgAllowed(arg)]
+
+# Run the linker or compiler.
+with open('ccproxy.log', 'a') as log:
+  log.write('## Called with %s\n' % ' '.join(sys.argv))
+  if any(i.startswith('-print-prog-name') for i in sys.argv):
+    # Redirect any program name queries to us.
+    print sys.argv[0]
+    ret = 0
+  elif call == LINK and 'libpython2.7.a' in sys.argv:
+    # We don't care about the final Python binary. Create a fake.
+    fake_python_file = open('python', 'w')
+    fake_python_file.write('#!/bin/bash\n')
+    fake_python_file.close()
+    ret = subprocess.call(['chmod', '+x', 'python'])
+  else:
+    log.write('** Calling %s %s\n\n' % (call, ' '.join(newargs)))
+    ret = subprocess.call([call] + newargs)
+    if call == LINK and 'Parser/pgen' in sys.argv:
+      # We want to compile the parser generator to native code.
+      target = 'Parser/pgen'
+      subprocess.call([LLC, '--filetype=obj', target, '-o', target + '.tmp.o'])
+      subprocess.call([CC, '-m32', target + '.tmp.o', '-o', target])
+      os.unlink(target + '.tmp.o')
+  # Pass the subprocess result to the caller.
+  sys.exit(ret)
diff --git a/map_filesystem.py b/map_filesystem.py
new file mode 100755
index 0000000..b56edac
--- /dev/null
+++ b/map_filesystem.py
@@ -0,0 +1,30 @@
+#!/usr/bin/env python2
+
+import os
+import sys
+
+def main(root, main_filename):
+  os.chdir(root)
+  commands = []
+  for (dirpath, dirnames, filenames) in os.walk('.'):
+    for folder in dirnames:
+      commands.append('FS.createFolder("%s", "%s", true, true);' %
+                      (dirpath, folder))
+    for filename in filenames:
+      jsless_filename = filename[:-3] if filename.endswith('.js') else filename
+      commands.append('FS.createLazyFile("%s", "%s", "%s", true, false);' %
+                      (dirpath, jsless_filename, filename))
+
+  infile = open(main_filename, 'r')
+  src = infile.read().replace('// {{PRE_RUN_ADDITIONS}}', '\n'.join(commands))
+  infile.close()
+
+  outfile = open(main_filename, 'w')
+  outfile.write(src)
+  outfile.close()
+
+if __name__ == '__main__':
+  if len(sys.argv) != 3:
+    print 'Usage: %s root outfile' % sys.argv[0]
+  else:
+    main(sys.argv[1], sys.argv[2])