diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -587,6 +587,9 @@
 coreconfigitem('experimental', 'revlogv2',
     default=None,
 )
+coreconfigitem('experimental', 'revisions.disambiguatewithin',
+    default=None,
+)
 coreconfigitem('experimental', 'single-head-per-branch',
     default=False,
 )
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -437,9 +437,26 @@
     return '%d:%s' % (rev, hexfunc(node))
 
 def resolvehexnodeidprefix(repo, prefix):
-    # Uses unfiltered repo because it's faster when prefix is ambiguous/
-    # This matches the shortesthexnodeidprefix() function below.
-    node = repo.unfiltered().changelog._partialmatch(prefix)
+    try:
+        # Uses unfiltered repo because it's faster when prefix is ambiguous/
+        # This matches the shortesthexnodeidprefix() function below.
+        node = repo.unfiltered().changelog._partialmatch(prefix)
+    except error.AmbiguousPrefixLookupError:
+        revset = repo.ui.config('experimental', 'revisions.disambiguatewithin')
+        if revset:
+            # Clear config to avoid infinite recursion
+            configoverrides = {('experimental',
+                                'revisions.disambiguatewithin'): None}
+            with repo.ui.configoverride(configoverrides):
+                revs = repo.anyrevs([revset], user=True)
+                matches = []
+                for rev in revs:
+                    node = repo.changelog.node(rev)
+                    if hex(node).startswith(prefix):
+                        matches.append(node)
+                if len(matches) == 1:
+                    return matches[0]
+        raise
     if node is None:
         return
     repo.changelog.rev(node)  # make sure node isn't filtered
diff --git a/tests/test-revisions.t b/tests/test-revisions.t
new file mode 100644
--- /dev/null
+++ b/tests/test-revisions.t
@@ -0,0 +1,37 @@
+  $ hg init repo
+  $ cd repo
+
+  $ echo 0 > a
+  $ hg ci -qAm 0
+  $ for i in 5 8 14 43; do
+  >   hg up -q 0
+  >   echo $i > a
+  >   hg ci -qm $i
+  > done
+  $ cat <<EOF >> .hg/hgrc
+  > [alias]
+  > l = log -T '{rev}:{shortest(node,1)}\n'
+  > EOF
+
+  $ hg l
+  4:7ba5d
+  3:7ba57
+  2:72
+  1:9
+  0:b
+  $ cat <<EOF >> .hg/hgrc
+  > [experimental]
+  > revisions.disambiguatewithin=:3
+  > EOF
+9 was unambiguous and still is
+  $ hg l -r 9
+  1:9
+7 was ambiguous and still is
+  $ hg l -r 7
+  abort: 00changelog.i@7: ambiguous identifier!
+  [255]
+7b is no longer ambiguous
+  $ hg l -r 7b
+  3:7ba57
+
+  $ cd ..