diff --git a/libc/tools/genseccomp.py b/libc/tools/genseccomp.py
new file mode 100755
index 0000000..b82bb12
--- /dev/null
+++ b/libc/tools/genseccomp.py
@@ -0,0 +1,171 @@
+#!/usr/bin/env python
+import os
+from subprocess import Popen, PIPE
+import textwrap
+from gensyscalls import SysCallsTxtParser
+
+
+syscall_file = "SYSCALLS.TXT"
+
+
+class SyscallRange(object):
+  def __init__(self, name, value):
+    self.names = [name]
+    self.begin = value
+    self.end = self.begin + 1
+
+  def add(self, name, value):
+    if value != self.end:
+      raise ValueError
+    self.end += 1
+    self.names.append(name)
+
+
+def generate_bpf_jge(value, ge_target, less_target):
+  return "BPF_JUMP(BPF_JMP|BPF_JGE|BPF_K, {0}, {1}, {2})".format(value, ge_target, less_target)
+
+
+# Converts the sorted ranges of allowed syscalls to a binary tree bpf
+# For a single range, output a simple jump to {fail} or {allow}. We can't set
+# the jump ranges yet, since we don't know the size of the filter, so use a
+# placeholder
+# For multiple ranges, split into two, convert the two halves and output a jump
+# to the correct half
+def convert_to_bpf(ranges):
+  if len(ranges) == 1:
+    # We will replace {fail} and {allow} with appropriate range jumps later
+    return [generate_bpf_jge(ranges[0].end, "{fail}", "{allow}") +
+            ", //" + "|".join(ranges[0].names)]
+  else:
+    half = (len(ranges) + 1) / 2
+    first = convert_to_bpf(ranges[:half])
+    second = convert_to_bpf(ranges[half:])
+    return [generate_bpf_jge(ranges[half].begin, len(first), 0) + ","] + first + second
+
+
+def construct_bpf(architecture, header_dir, output_path):
+  parser = SysCallsTxtParser()
+  parser.parse_file(syscall_file)
+  syscalls = parser.syscalls
+
+  # Select only elements matching required architecture
+  syscalls = [x for x in syscalls if architecture in x and x[architecture]]
+
+  # We only want the name
+  names = [x["name"] for x in syscalls]
+
+  # Run preprocessor over the __NR_syscall symbols, including unistd.h,
+  # to get the actual numbers
+  prefix = "__SECCOMP_"  # prefix to ensure no name collisions
+  cpp = Popen(["../../prebuilts/clang/host/linux-x86/clang-stable/bin/clang",
+               "-E", "-nostdinc", "-I" + header_dir, "-Ikernel/uapi/", "-"],
+              stdin=PIPE, stdout=PIPE)
+  cpp.stdin.write("#include <asm/unistd.h>\n")
+  for name in names:
+    # In SYSCALLS.TXT, there are two arm-specific syscalls whose names start
+    # with __ARM__NR_. These we must simply write out as is.
+    if not name.startswith("__ARM_NR_"):
+      cpp.stdin.write(prefix + name + ", __NR_" + name + "\n")
+    else:
+      cpp.stdin.write(prefix + name + ", " + name + "\n")
+  content = cpp.communicate()[0].split("\n")
+
+  # The input is now the preprocessed source file. This will contain a lot
+  # of junk from the preprocessor, but our lines will be in the format:
+  #
+  #     __SECCOMP_${NAME}, (0 + value)
+
+  syscalls = []
+  for line in content:
+    if not line.startswith(prefix):
+      continue
+
+    # We might pick up extra whitespace during preprocessing, so best to strip.
+    name, value = [w.strip() for w in line.split(",")]
+    name = name[len(prefix):]
+
+    # Note that some of the numbers were expressed as base + offset, so we
+    # need to eval, not just int
+    value = eval(value)
+    syscalls.append((name, value))
+
+  # Sort the values so we convert to ranges and binary chop
+  syscalls = sorted(syscalls, lambda x, y: cmp(x[1], y[1]))
+
+  # Turn into a list of ranges. Keep the names for the comments
+  ranges = []
+  for name, value in syscalls:
+    if not ranges:
+      ranges.append(SyscallRange(name, value))
+      continue
+
+    last_range = ranges[-1]
+    if last_range.end == value:
+      last_range.add(name, value)
+    else:
+      ranges.append(SyscallRange(name, value))
+
+  bpf = convert_to_bpf(ranges)
+
+  # Now we know the size of the tree, we can substitute the {fail} and {allow}
+  # placeholders
+  for i, statement in enumerate(bpf):
+    # Replace placeholder with
+    # "distance to jump to fail, distance to jump to allow"
+    # We will add a kill statement and an allow statement after the tree
+    # With bpfs jmp 0 means the next statement, so the distance to the end is
+    # len(bpf) - i - 1, which is where we will put the kill statement, and
+    # then the statement after that is the allow statement
+    if "{fail}" in statement and "{allow}" in statement:
+      bpf[i] = statement.format(fail=str(len(bpf) - i - 1),
+                                allow=str(len(bpf) - i))
+
+  # Add check that we aren't off the bottom of the syscalls
+  bpf.insert(0,
+             "BPF_JUMP(BPF_JMP|BPF_JGE|BPF_K, " + str(ranges[0].begin) +
+             ", 0, " + str(len(bpf)) + "),")
+
+  # Add the error and allow calls at the end
+  bpf.append("BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),")
+  bpf.append("BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),")
+
+  # And output policy
+  header = textwrap.dedent("""\
+    // Autogenerated file - edit at your peril!!
+
+    #include <linux/filter.h>
+    #include <errno.h>
+
+    #include "seccomp_policy.h"
+    const struct sock_filter {architecture}_filter[] = {{
+    """).format(architecture=architecture)
+
+  footer = textwrap.dedent("""\
+
+    }};
+
+    const size_t {architecture}_filter_size = sizeof({architecture}_filter) / sizeof(struct sock_filter);
+    """).format(architecture=architecture)
+  output = header + "\n".join(bpf) + footer
+
+  existing = ""
+  if os.path.isfile(output_path):
+    existing = open(output_path).read()
+  if output == existing:
+    print "File " + output_path + " not changed."
+  else:
+    with open(output_path, "w") as output_file:
+      output_file.write(output)
+
+    print "Generated file " + output_path
+
+
+def main():
+  # Set working directory for predictable results
+  os.chdir(os.path.join(os.environ["ANDROID_BUILD_TOP"], "bionic/libc"))
+  construct_bpf("arm", "kernel/uapi/asm-arm", "seccomp/arm_policy.c")
+  construct_bpf("arm64", "kernel/uapi/asm-arm64", "seccomp/arm64_policy.c")
+
+
+if __name__ == "__main__":
+  main()