diff --git a/tools/parsedeps.py b/tools/parsedeps.py
new file mode 100755
index 0000000..32d8ad7
--- /dev/null
+++ b/tools/parsedeps.py
@@ -0,0 +1,151 @@
+#!/usr/bin/env python
+# vim: ts=2 sw=2
+
+import optparse
+import re
+import sys
+
+
+class Dependency:
+  def __init__(self, tgt):
+    self.tgt = tgt
+    self.pos = ""
+    self.prereqs = set()
+    self.visit = 0
+
+  def add(self, prereq):
+    self.prereqs.add(prereq)
+
+
+class Dependencies:
+  def __init__(self):
+    self.lines = {}
+    self.__visit = 0
+    self.count = 0
+
+  def add(self, tgt, prereq):
+    t = self.lines.get(tgt)
+    if not t:
+      t = Dependency(tgt)
+      self.lines[tgt] = t
+    p = self.lines.get(prereq)
+    if not p:
+      p = Dependency(prereq)
+      self.lines[prereq] = p
+    t.add(p)
+    self.count = self.count + 1
+
+  def setPos(self, tgt, pos):
+    t = self.lines.get(tgt)
+    if not t:
+      t = Dependency(tgt)
+      self.lines[tgt] = t
+    t.pos = pos
+
+  def get(self, tgt):
+    if self.lines.has_key(tgt):
+      return self.lines[tgt]
+    else:
+      return None
+
+  def __iter__(self):
+    return self.lines.iteritems()
+
+  def trace(self, tgt, prereq):
+    self.__visit = self.__visit + 1
+    d = self.lines.get(tgt)
+    if not d:
+      return
+    return self.__trace(d, prereq)
+
+  def __trace(self, d, prereq):
+    if d.visit == self.__visit:
+      return d.trace
+    if d.tgt == prereq:
+      return [ [ d ], ]
+    d.visit = self.__visit
+    result = []
+    for pre in d.prereqs:
+      recursed = self.__trace(pre, prereq)
+      for r in recursed:
+        result.append([ d ] + r)
+    d.trace = result
+    return result
+
+def help():
+  print "Commands:"
+  print "  dep TARGET             Print the prerequisites for TARGET"
+  print "  trace TARGET PREREQ    Print the paths from TARGET to PREREQ"
+
+
+def main(argv):
+  opts = optparse.OptionParser()
+  opts.add_option("-i", "--interactive", action="store_true", dest="interactive",
+                    help="Interactive mode")
+  (options, args) = opts.parse_args()
+
+  deps = Dependencies()
+
+  filename = args[0]
+  print "Reading %s" % filename
+
+  if True:
+    f = open(filename)
+    for line in f:
+      line = line.strip()
+      if len(line) > 0:
+        if line[0] == '#':
+          pos,tgt = line.rsplit(":", 1)
+          pos = pos[1:].strip()
+          tgt = tgt.strip()
+          deps.setPos(tgt, pos)
+        else:
+          (tgt,prereq) = line.split(':', 1)
+          tgt = tgt.strip()
+          prereq = prereq.strip()
+          deps.add(tgt, prereq)
+    f.close()
+
+  print "Read %d dependencies. %d targets." % (deps.count, len(deps.lines))
+  while True:
+    line = raw_input("target> ")
+    if not line.strip():
+      continue
+    split = line.split()
+    cmd = split[0]
+    if len(split) == 2 and cmd == "dep":
+      tgt = split[1]
+      d = deps.get(tgt)
+      if d:
+        for prereq in d.prereqs:
+          print prereq.tgt
+    elif len(split) == 3 and cmd == "trace":
+      tgt = split[1]
+      prereq = split[2]
+      if False:
+        print "from %s to %s" % (tgt, prereq)
+      trace = deps.trace(tgt, prereq)
+      if trace:
+        width = 0
+        for g in trace:
+          for t in g:
+            if len(t.tgt) > width:
+              width = len(t.tgt)
+        for g in trace:
+          for t in g:
+            if t.pos:
+              print t.tgt, " " * (width-len(t.tgt)), "  #", t.pos
+            else:
+              print t.tgt
+          print
+    else:
+      help()
+
+if __name__ == "__main__":
+  try:
+    main(sys.argv)
+  except KeyboardInterrupt:
+    print
+  except EOFError:
+    print
+