diff --git a/hgext/convert/hg.py b/hgext/convert/hg.py
--- a/hgext/convert/hg.py
+++ b/hgext/convert/hg.py
@@ -217,7 +217,8 @@
         """
         anc = [p1ctx.ancestor(p2ctx)]
         # Calculate what files are coming from p2
-        actions, diverge, rename = mergemod.calculateupdates(
+        # TODO: this might be achieved using commitinfo
+        actions, diverge, rename, commitinfo = mergemod.calculateupdates(
             self.repo,
             p1ctx,
             p2ctx,
diff --git a/hgext/largefiles/overrides.py b/hgext/largefiles/overrides.py
--- a/hgext/largefiles/overrides.py
+++ b/hgext/largefiles/overrides.py
@@ -543,12 +543,12 @@
     origfn, repo, p1, p2, pas, branchmerge, force, acceptremote, *args, **kwargs
 ):
     overwrite = force and not branchmerge
-    actions, diverge, renamedelete = origfn(
+    actions, diverge, renamedelete, commitinfo = origfn(
         repo, p1, p2, pas, branchmerge, force, acceptremote, *args, **kwargs
     )
 
     if overwrite:
-        return actions, diverge, renamedelete
+        return actions, diverge, renamedelete, commitinfo
 
     # Convert to dictionary with filename as key and action as value.
     lfiles = set()
@@ -620,7 +620,7 @@
                 actions[lfile] = (b'g', largs, b'replaces standin')
                 actions[standin] = (b'r', None, b'replaced by non-standin')
 
-    return actions, diverge, renamedelete
+    return actions, diverge, renamedelete, commitinfo
 
 
 @eh.wrapfunction(mergestatemod, b'recordupdates')
diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -565,6 +565,8 @@
     diverge: mapping of source name -> list of dest name for divergent renames
     renamedelete: mapping of source name -> list of destinations for files
                   deleted on one side and renamed on other.
+    commitinfo: dict containing data which should be used on commit
+                contains a filename -> info mapping
     """
     if matcher is not None and matcher.always():
         matcher = None
@@ -578,6 +580,10 @@
     branch_copies1 = copies.branch_copies()
     branch_copies2 = copies.branch_copies()
     diverge = {}
+    # information from merge which is needed at commit time
+    # for example choosing filelog of which parent to commit
+    # TODO: use specific constants in future for this mapping
+    commitinfo = {}
     if followcopies:
         branch_copies1, branch_copies2, diverge = copies.mergecopies(
             repo, wctx, p2, pa
@@ -671,6 +677,8 @@
                             (fl2, False),
                             b'remote is newer',
                         )
+                        if branchmerge:
+                            commitinfo[f] = b'other'
                 elif nol and n2 == a:  # remote only changed 'x'
                     actions[f] = (
                         mergestatemod.ACTION_EXEC,
@@ -685,6 +693,8 @@
                         (fl1, False),
                         b'remote is newer',
                     )
+                    if branchmerge:
+                        commitinfo[f] = b'other'
                 else:  # both changed something
                     actions[f] = (
                         mergestatemod.ACTION_MERGE,
@@ -846,7 +856,7 @@
     renamedelete = branch_copies1.renamedelete
     renamedelete.update(branch_copies2.renamedelete)
 
-    return actions, diverge, renamedelete
+    return actions, diverge, renamedelete, commitinfo
 
 
 def _resolvetrivial(repo, wctx, mctx, ancestor, actions):
@@ -892,13 +902,13 @@
 
     Also filters out actions which are unrequired if repository is sparse.
 
-    Returns same 3 element tuple as manifestmerge().
+    Returns same 4 element tuple as manifestmerge().
     """
     # Avoid cycle.
     from . import sparse
 
     if len(ancestors) == 1:  # default
-        actions, diverge, renamedelete = manifestmerge(
+        actions, diverge, renamedelete, commitinfo = manifestmerge(
             repo,
             wctx,
             mctx,
@@ -928,7 +938,7 @@
         diverge, renamedelete = None, None
         for ancestor in ancestors:
             repo.ui.note(_(b'\ncalculating bids for ancestor %s\n') % ancestor)
-            actions, diverge1, renamedelete1 = manifestmerge(
+            actions, diverge1, renamedelete1, commitinfo = manifestmerge(
                 repo,
                 wctx,
                 mctx,
@@ -1011,7 +1021,7 @@
     )
     _resolvetrivial(repo, wctx, mctx, ancestors[0], actions)
 
-    return prunedactions, diverge, renamedelete
+    return prunedactions, diverge, renamedelete, commitinfo
 
 
 def _getcwd():
@@ -1735,7 +1745,7 @@
             followcopies = False
 
         ### calculate phase
-        actionbyfile, diverge, renamedelete = calculateupdates(
+        actionbyfile, diverge, renamedelete, commitinfo = calculateupdates(
             repo,
             wc,
             p2,