diff --git a/testbild.py b/testbild.py
new file mode 100755
index 000000000..3dea1be6b
--- /dev/null
+++ b/testbild.py
@@ -0,0 +1,161 @@
+#!/usr/bin/env python
+from collections import OrderedDict
+
+"""
+This script uses my experimental build tool http://www.bildtool.org
+
+In order to build the complete ANTLR4 product with Java, CSharp, Python 2/3, and JavaScript
+targets, do the following from a UNIX command line.  Windows build using this script
+is not yet supported.
+
+You will also need python 2.7, python 3.4, node.js and mono (on Mac/Linux)
+
+mkdir -p /usr/local/antlr # somewhere appropriate where you want to install stuff
+cd /usr/local/antlr
+git clone git@github.com:antlr/antlr4.git
+cd antlr4
+./testbild.py tests
+
+This script must be run from the main antlr4 directory.
+"""
+
+# bootstrap by downloading bilder.py if not found
+import urllib
+import os
+
+if not os.path.exists("bilder.py"):
+    print "bootstrapping; downloading bilder.py"
+    urllib.urlretrieve(
+        "https://raw.githubusercontent.com/parrt/bild/master/src/python/bilder.py",
+        "bilder.py")
+
+# assumes bilder.py is in current directory
+from bilder import *
+
+BOOTSTRAP_VERSION = "4.5"
+VERSION = "4.5.1"
+
+TARGETS = ["Java", "CSharp", "Python2", "Python3", "JavaScript"]
+
+TOOL_PATH = []
+TEST_PATH = []
+
+BUILD = "build"
+
+JUNIT = ["junit-4.11.jar", "hamcrest-core-1.3.jar"]
+
+RUNTIME_SRC = ["runtime/Java/src","gen4"]
+RUNTIME_DEP = ["antlr-"+BOOTSTRAP_VERSION+"-complete.jar"]
+RUNTIME_RES = []
+
+RUNTIME_TEST_SRC = ["runtime-testsuite/test"]
+RUNTIME_TEST_DEP = RUNTIME_DEP + JUNIT
+RUNTIME_TEST_RES = []
+RUNTIME_TEST_MOD_DEP = ["runtime"]
+RUNTIME_TEST_SKIP = [
+    'org/antlr/v4/test/runtime/javascript/firefox',
+    'org/antlr/v4/test/runtime/javascript/chrome',
+    'org/antlr/v4/test/runtime/javascript/explorer',
+    'org/antlr/v4/test/runtime/javascript/safari',
+]
+
+TOOL_SRC = ["gen3", "tool/src"]
+TOOL_DEP = ["antlr-3.5.2-runtime.jar", "ST-4.0.8.jar"]
+TOOL_RES = ["tool/resources"]
+TOOL_MOD_DEP = ["runtime"]
+
+TOOLTEST_SRC = ["tool-testsuite/test"]
+TOOLTEST_DEP = ["antlr-3.5.2-runtime.jar", "ST-4.0.8.jar"] + JUNIT
+TOOLTEST_RES = ["tool-testsuite/test/org/antlr/v4/test/tool"] + TOOL_RES # some grammars in the code area
+TOOLTEST_MOD_DEP = ["tool", "runtime", "runtime-tests"]
+
+def download_libs():
+    global junit_jar, hamcrest_jar
+    junit_jar, hamcrest_jar = load_junitjars()
+    depends("http://www.antlr3.org/download/antlr-3.5.2-runtime.jar")
+    depends("http://www.stringtemplate.org/download/ST-4.0.8.jar")
+    copyfile(src="runtime/Java/lib/org.abego.treelayout.core.jar", trg=JARCACHE)
+
+
+def mycompile(goal,srcpaths,dependencies,skip=[]):
+    args = ["-Xlint", "-Xlint:-serial", "-g"]
+    jars=None
+    trgdir = os.path.join(BUILD, goal)
+    if len(dependencies)>0:
+        dependencies = [uniformpath(d) for d in dependencies] # need absolute paths for CLASSPATH
+        jars = string.join(dependencies, os.pathsep)
+    jars += os.pathsep+trgdir # we can also see the code we're generating
+    args += ["-sourcepath", string.join(srcpaths, ":")] # javac says always ':'
+    for src in srcpaths:
+        javac(srcdir=src, trgdir=trgdir, version="1.6", cp=jars, args=args, skip=skip)
+
+def parsers():
+    antlr3("tool/src/org/antlr/v4/parse", "gen3", version="3.5.2", package="org.antlr.v4.parse")
+    antlr3("tool/src/org/antlr/v4/codegen", "gen3", version="3.5.2", package="org.antlr.v4.codegen",
+           args=["-lib", uniformpath("gen3/org/antlr/v4/parse")])
+    antlr4("runtime/Java/src/org/antlr/v4/runtime/tree/xpath", "gen4",
+           version=BOOTSTRAP_VERSION, package="org.antlr.v4.runtime.tree.xpath")
+
+def runtime():
+    require(parsers)
+    mycompile("runtime",
+              RUNTIME_SRC,
+              [os.path.join(JARCACHE,d) for d in RUNTIME_DEP])
+
+def tool():
+    require(parsers)
+    require(runtime)
+    mycompile("tool",
+              TOOL_SRC,
+              [os.path.join(JARCACHE,d) for d in TOOL_DEP] +
+              [os.path.join(BUILD,d) for d in TOOL_MOD_DEP])
+
+
+def runtime_tests():
+    require(runtime)
+    mycompile("runtime-tests",
+              RUNTIME_TEST_SRC,
+              [os.path.join(JARCACHE,d) for d in RUNTIME_TEST_DEP] +
+              [os.path.join(BUILD,d) for d in RUNTIME_TEST_MOD_DEP],
+              skip=RUNTIME_TEST_SKIP)
+
+
+def tool_tests():
+    require(runtime_tests)
+    require(tool)
+    mycompile("tool-tests",
+              TOOLTEST_SRC,
+              [os.path.join(JARCACHE,d) for d in TOOLTEST_DEP] +
+              [os.path.join(BUILD,d) for d in TOOLTEST_MOD_DEP])
+    cp = [os.path.join(JARCACHE,d) for d in TOOLTEST_DEP] +\
+         TOOLTEST_RES +\
+         [os.path.join(BUILD,d) for d in TOOLTEST_MOD_DEP]
+    cp = [uniformpath(p) for p in cp]
+    junit(os.path.join(BUILD,"tool-tests"), cp=string.join(cp,os.pathsep), verbose=False)
+
+def regen_tests():
+    """
+    Generate all runtime Test*.java files for all targets into
+    runtime-testsuite/test/org/antlr/v4/test/runtime/targetname
+    """
+
+
+def clean(dist=True):
+    if dist:
+        rmdir("dist")
+    rmdir(BUILD)
+    rmdir("gen3")
+    rmdir("gen4")
+    rmdir("doc")
+
+
+def all():
+    download_libs()
+    runtime()
+    tool()
+
+
+def depends(url):
+    download(url, JARCACHE)
+
+processargs(globals())  # E.g., "python bild.py all"