diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -2060,6 +2060,62 @@
             printrecords(2)
 
 
+@command(b'debugmergestatetemplated', [] + cmdutil.templateopts, b'')
+def debugmergestatetemplated(ui, repo, *args, **opts):
+    """templated output about the merge state
+
+    This command requires a template (such as '-T json').
+    """
+
+    opts = pycompat.byteskwargs(opts)
+    if not opts[b'template']:
+        raise error.Abort(_(b'template required'))
+
+    ms = mergemod.mergestate.read(repo)
+    if not ms.active():
+        return
+
+    fm = ui.formatter(b'debugmergestatetemplated', opts)
+    fm.startitem()
+
+    fm_commits = fm.nested(b'commits')
+    for name, node, label_index in (
+        (b'local', ms.local, 0),
+        (b'other', ms.other, 1),
+    ):
+        fm_commits.startitem()
+        fm_commits.data(name=name)
+        fm_commits.data(node=hex(node))
+        if ms._labels and len(ms._labels) > label_index:
+            fm_commits.data(label=ms._labels[label_index])
+    fm_commits.end()
+
+    fm_files = fm.nested(b'files')
+    for f in ms:
+        fm_files.startitem()
+        fm_files.data(name=f)
+        state = ms._state[f]
+        fm_files.data(state=state[0])
+        if state[0] == mergemod.MERGE_RECORD_UNRESOLVED:
+            fm_files.data(local_key=state[1])
+            fm_files.data(local_path=state[2])
+            fm_files.data(ancestor_path=state[3])
+            fm_files.data(ancestor_node=state[4])
+            fm_files.data(other_path=state[5])
+            fm_files.data(other_node=state[6])
+            fm_files.data(local_flags=state[7])
+        fm_extras = fm_files.nested(b'extras')
+        for k, v in ms.extras(f).items():
+            fm_extras.startitem()
+            fm_extras.data(key=k)
+            fm_extras.data(value=v)
+        fm_extras.end()
+
+    fm_files.end()
+
+    fm.end()
+
+
 @command(b'debugnamecomplete', [], _(b'NAME...'))
 def debugnamecomplete(ui, repo, *args):
     '''complete "names" - tags, open branch names, bookmark names'''
diff --git a/tests/test-completion.t b/tests/test-completion.t
--- a/tests/test-completion.t
+++ b/tests/test-completion.t
@@ -106,6 +106,7 @@
   debuglocks
   debugmanifestfulltextcache
   debugmergestate
+  debugmergestatetemplated
   debugnamecomplete
   debugnodemap
   debugobsolete
@@ -290,6 +291,7 @@
   debuglocks: force-lock, force-wlock, set-lock, set-wlock
   debugmanifestfulltextcache: clear, add
   debugmergestate: 
+  debugmergestatetemplated: style, template
   debugnamecomplete: 
   debugnodemap: dump-new, dump-disk, check, metadata
   debugobsolete: flags, record-parents, rev, exclusive, index, delete, date, user, template
diff --git a/tests/test-help.t b/tests/test-help.t
--- a/tests/test-help.t
+++ b/tests/test-help.t
@@ -1022,6 +1022,8 @@
                  cache
    debugmergestate
                  print merge state
+   debugmergestatetemplated
+                 templated output about the merge state
    debugnamecomplete
                  complete "names" - tags, open branch names, bookmark names
    debugnodemap  write and inspect on disk nodemap
diff --git a/tests/test-resolve.t b/tests/test-resolve.t
--- a/tests/test-resolve.t
+++ b/tests/test-resolve.t
@@ -327,6 +327,20 @@
   R file1
   U file2
 
+test debugmergestatetemplate
+
+  $ hg debugmergestatetemplated
+  abort: template required
+  [255]
+  $ hg debugmergestatetemplated -T json
+  [
+   {
+    "commits": [{"label": "working copy", "name": "local", "node": "57653b9f834a4493f7240b0681efcb9ae7cab745"}, {"label": "merge rev", "name": "other", "node": "dc77451844e37f03f5c559e3b8529b2b48d381d1"}],
+    "files": [{"extras": [{"key": "ancestorlinknode", "value": "99726c03216e233810a2564cbc0adfe395007eac"}], "name": "file1", "state": "r"}, {"ancestor_node": "2ed2a3912a0b24502043eae84ee4b279c18b90dd", "ancestor_path": "file2", "extras": [{"key": "ancestorlinknode", "value": "99726c03216e233810a2564cbc0adfe395007eac"}], "local_flags": "", "local_key": "cb99b709a1978bd205ab9dfd4c5aaa1fc91c7523", "local_path": "file2", "name": "file2", "other_node": "6f4310b00b9a147241b071a60c28a650827fb03d", "other_path": "file2", "state": "u"}]
+   }
+  ]
+
+
 insert unsupported mandatory merge record
 
   $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -X