diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -10,6 +10,7 @@ from i18n import _
 import os, sys, errno, re, glob, tempfile
 import mdiff, bdiff, util, templater, patch, error, encoding, templatekw
 import match as _match
+import similar
 
 revrangesep = ':'
 
@@ -286,52 +287,6 @@ def matchall(repo):
 def matchfiles(repo, files):
     return _match.exact(repo.root, repo.getcwd(), files)
 
-def findrenames(repo, added, removed, threshold):
-    '''find renamed files -- yields (before, after, score) tuples'''
-    copies = {}
-    ctx = repo['.']
-    for i, r in enumerate(removed):
-        repo.ui.progress(_('searching'), i, total=len(removed))
-        if r not in ctx:
-            continue
-        fctx = ctx.filectx(r)
-
-        # lazily load text
-        @util.cachefunc
-        def data():
-            orig = fctx.data()
-            return orig, mdiff.splitnewlines(orig)
-
-        def score(text):
-            if not len(text):
-                return 0.0
-            if not fctx.cmp(text):
-                return 1.0
-            if threshold == 1.0:
-                return 0.0
-            orig, lines = data()
-            # bdiff.blocks() returns blocks of matching lines
-            # count the number of bytes in each
-            equal = 0
-            matches = bdiff.blocks(text, orig)
-            for x1, x2, y1, y2 in matches:
-                for line in lines[y1:y2]:
-                    equal += len(line)
-
-            lengths = len(text) + len(orig)
-            return equal * 2.0 / lengths
-
-        for a in added:
-            bestscore = copies.get(a, (None, threshold))[1]
-            myscore = score(repo.wread(a))
-            if myscore >= bestscore:
-                copies[a] = (r, myscore)
-    repo.ui.progress(_('searching'), None)
-
-    for dest, v in copies.iteritems():
-        source, score = v
-        yield source, dest, score
-
 def addremove(repo, pats=[], opts={}, dry_run=None, similarity=None):
     if dry_run is None:
         dry_run = opts.get('dry_run')
@@ -366,8 +321,8 @@ def addremove(repo, pats=[], opts={}, dr
             added.append(abs)
     copies = {}
     if similarity > 0:
-        for old, new, score in findrenames(repo, added + unknown,
-                                           removed + deleted, similarity):
+        for old, new, score in similar.findrenames(repo,
+                added + unknown, removed + deleted, similarity):
             if repo.ui.verbose or not m.exact(old) or not m.exact(new):
                 repo.ui.status(_('recording removal of %s as rename to %s '
                                  '(%d%% similar)\n') %
diff --git a/mercurial/similar.py b/mercurial/similar.py
new file mode 100644
--- /dev/null
+++ b/mercurial/similar.py
@@ -0,0 +1,59 @@
+# similar.py - mechanisms for finding similar files
+#
+# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from i18n import _
+import util
+import mdiff
+import bdiff
+
+def findrenames(repo, added, removed, threshold):
+    '''find renamed files -- yields (before, after, score) tuples'''
+    copies = {}
+    ctx = repo['.']
+    for i, r in enumerate(removed):
+        repo.ui.progress(_('searching'), i, total=len(removed))
+        if r not in ctx:
+            continue
+        fctx = ctx.filectx(r)
+
+        # lazily load text
+        @util.cachefunc
+        def data():
+            orig = fctx.data()
+            return orig, mdiff.splitnewlines(orig)
+
+        def score(text):
+            if not len(text):
+                return 0.0
+            if not fctx.cmp(text):
+                return 1.0
+            if threshold == 1.0:
+                return 0.0
+            orig, lines = data()
+            # bdiff.blocks() returns blocks of matching lines
+            # count the number of bytes in each
+            equal = 0
+            matches = bdiff.blocks(text, orig)
+            for x1, x2, y1, y2 in matches:
+                for line in lines[y1:y2]:
+                    equal += len(line)
+
+            lengths = len(text) + len(orig)
+            return equal * 2.0 / lengths
+
+        for a in added:
+            bestscore = copies.get(a, (None, threshold))[1]
+            myscore = score(repo.wread(a))
+            if myscore >= bestscore:
+                copies[a] = (r, myscore)
+    repo.ui.progress(_('searching'), None)
+
+    for dest, v in copies.iteritems():
+        source, score = v
+        yield source, dest, score
+
+