diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -590,6 +590,11 @@
 coreconfigitem(
     b'experimental', b'maxdeltachainspan', default=-1,
 )
+# tracks files which were undeleted (merge might delete them but we explicitly
+# kept/undeleted them) and creates new filenodes for them
+coreconfigitem(
+    b'experimental', b'merge-track-undeleted', default=False,
+)
 coreconfigitem(
     b'experimental', b'mergetempdirprefix', default=None,
 )
diff --git a/tests/test-merge-criss-cross.t b/tests/test-merge-criss-cross.t
--- a/tests/test-merge-criss-cross.t
+++ b/tests/test-merge-criss-cross.t
@@ -486,6 +486,14 @@
 explicit choices made by users to revert the removal and on criss-cross merging
 removes the file again.
 
+Enable the config option
+------------------------
+
+  $ cat >> $HGRCPATH <<EOF
+  > [experimental]
+  > merge-track-undeleted = True
+  > EOF
+
 "Simple" case where the filenode changes
 ----------------------------------------