diff --git a/tools/filter_openocd_log.py b/tools/filter_openocd_log.py
new file mode 100755
index 000000000..b7ae6e0e8
--- /dev/null
+++ b/tools/filter_openocd_log.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+
+import sys
+
+# This function is the only OpenOCD-specific part of this script.
+def make_canonical(line):
+    # Remove the line number and time stamp.
+    parts = line.split(None, 3)
+    if len(parts) > 3:
+        return "%s - - %s" % (parts[0], parts[3])
+    else:
+        return line
+
+def buf_startswith(buf, sequence):
+    if len(buf) < len(sequence):
+        return False
+    for i, entry in enumerate(sequence):
+        if entry[1] != buf[i][1]:
+            return False
+    return True
+
+def shorten_buffer(outfd, buf, current_repetition):
+    """Do something to the buffer to make it shorter. If we can't compress
+    anything, then print out the first line and remove it."""
+    length_before = len(buf)
+
+    if current_repetition:
+        while buf_startswith(buf, current_repetition[0]):
+            del buf[:len(current_repetition[0])]
+            current_repetition[1] += 1
+        if len(buf) < length_before:
+            return current_repetition
+        outfd.write("## The following %d lines repeat %d times:\n" % (
+                len(current_repetition[0]), current_repetition[1]))
+        for entry in current_repetition[0]:
+            outfd.write("# %s" % entry[1])
+
+    # Look for repeated sequences...
+    repetitions = []
+    for length in range(1, len(buf)/2):
+        # Is there a repeating sequence of `length` lines?
+        matched_lines = 0
+        for i, entry in enumerate(buf[length:]):
+            if entry[1] == buf[i % length][1]:
+                matched_lines += 1
+            else:
+                break
+        if matched_lines >= length:
+            repetitions.append((matched_lines + length, length))
+
+    if repetitions:
+        repetitions.sort(key=lambda entry: (entry[0] * (entry[1] / entry[0]), -entry[1]))
+        matched_lines, length = repetitions[-1]
+        repeated = matched_lines / length
+        if repeated * length >= 3:
+            sequence = buf[:length]
+            del buf[:repeated * length]
+
+            if matched_lines == length_before:
+                # Could be continued...
+                return [sequence, repeated]
+
+            else:
+                outfd.write("## The following %d lines repeat %d times:\n" %
+                        (length, repeated))
+                for entry in sequence:
+                    outfd.write("# %s" % entry[1])
+                return None
+
+    if len(buf) >= length_before:
+        line, _ = buf[0]
+        outfd.write(line)
+        buf.pop(0)
+
+    if length_before <= len(buf):
+        print "Buffer:"
+        for entry in buf:
+            print "%r" % entry[0]
+        assert False
+
+    return None
+
+def compress_log(infd, outfd, window):
+    """Compress log by finding repeated runs of lines. Runs in O(lines *
+    window**2), which can probably be improved."""
+    # Contains line, canonical tuples
+    buf = []
+    current_repetition = None
+
+    for line in infd:
+        buf.append((line, make_canonical(line)))
+        if len(buf) > window:
+            current_repetition = shorten_buffer(outfd, buf, current_repetition)
+
+    while len(buf) > 0:
+        current_repetition = shorten_buffer(outfd, buf, current_repetition)
+
+def main(args):
+    import argparse
+    parser = argparse.ArgumentParser(
+            description='Combine repeated OpenOCD debug output lines. This is '
+            'very helpful when looking at verbose log files where e.g. target '
+            'polling is repeated over and over.',
+            epilog='If no files are specified, read standard input.',
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument('file', nargs='*', help='input file')
+    parser.add_argument('-o', '--output', help='output file', default=sys.stdout)
+    parser.add_argument('-w', '--window', type=int, default=100,
+            help='number of lines to consider when looking for repetitions')
+    args = parser.parse_args(args)
+
+    if args.file:
+        for f in args.file:
+            compress_log(open(f, "r"), args.output, args.window)
+    else:
+        compress_log(sys.stdin, args.output, args.window)
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv[1:]))