diff --git a/git-filter-repo b/git-filter-repo
index c1ff923..4532a16 100755
--- a/git-filter-repo
+++ b/git-filter-repo
@@ -1870,6 +1870,11 @@ EXAMPLES
                "merge commits have no file changes, they can be pruned.  The "
                "default ('auto') is to only prune empty merge commits which "
                "become degenerate (not which started as such)."))
+    parents.add_argument('--no-ff', action='store_true',
+        help=_("Even if the first parent is or becomes an ancestor of another "
+               "parent, do not prune it.  This modifies how "
+               "--prune-degenerate behaves, and may be useful in projects who "
+               "always use merge --no-ff."))
 
     callback = parser.add_argument_group(title=_("Generic callback code snippets"))
     callback.add_argument('--filename-callback', metavar="FUNCTION_BODY",
@@ -3034,6 +3039,12 @@ class RepoFilter(object):
            self._orig_graph.is_ancestor(orig_parents[cur],
                                         orig_parents[other]):
           continue
+        # Some folks want their history to have all first parents be merge
+        # commits (except for any root commits), and always do a merge --no-ff.
+        # For such folks, don't remove the first parent even if it's an
+        # ancestor of other commits.
+        if self._args.no_ff and cur == 0:
+          continue
         # Okay so the cur-th parent is an ancestor of the other-th parent,
         # and it wasn't that way in the original repository; mark the
         # cur-th parent as removable.
diff --git a/t/t9390-filter-repo.sh b/t/t9390-filter-repo.sh
index ea7508f..4003759 100755
--- a/t/t9390-filter-repo.sh
+++ b/t/t9390-filter-repo.sh
@@ -47,6 +47,7 @@ filter_testcase empty less-empty-keepme --path keepme --prune-empty=never \
 filter_testcase degenerate degenerate-keepme   --path moduleA/keepme
 filter_testcase degenerate degenerate-moduleA  --path moduleA
 filter_testcase degenerate degenerate-globme   --path-glob *me
+filter_testcase degenerate degenerate-keepme-noff --path moduleA/keepme --no-ff
 filter_testcase unusual unusual-filtered --path ''
 filter_testcase unusual unusual-mailmap  --mailmap ../t9390/sample-mailmap
 
diff --git a/t/t9390/degenerate-keepme-noff b/t/t9390/degenerate-keepme-noff
new file mode 100644
index 0000000..d28c7a4
--- /dev/null
+++ b/t/t9390/degenerate-keepme-noff
@@ -0,0 +1,113 @@
+feature done
+blob
+mark :1
+data 10
+keepme v1
+
+reset refs/heads/master
+commit refs/heads/master
+mark :2
+author Full Name <user@organization.tld> 2000000000 +0100
+committer Full Name <user@organization.tld> 2000000000 +0100
+data 2
+A
+M 100644 :1 moduleA/keepme
+
+blob
+mark :3
+data 10
+keepme v2
+
+commit refs/heads/branchO
+mark :4
+author Full Name <user@organization.tld> 2000050000 +0100
+committer Full Name <user@organization.tld> 2000050000 +0100
+data 2
+G
+from :2
+M 100644 :3 moduleA/keepme
+
+commit refs/heads/branchI
+mark :5
+author Full Name <user@organization.tld> 2000070000 +0100
+committer Full Name <user@organization.tld> 2000070000 +0100
+data 29
+I: Merge commit 'D' into 'H'
+from :4
+merge :2
+
+commit refs/heads/branchO
+mark :6
+author Full Name <user@organization.tld> 2000080000 +0100
+committer Full Name <user@organization.tld> 2000080000 +0100
+data 29
+J: Merge commit 'H' into 'D'
+from :2
+merge :4
+
+blob
+mark :7
+data 10
+keepme v3
+
+commit refs/heads/branchO
+mark :8
+author Full Name <user@organization.tld> 2000092000 +0100
+committer Full Name <user@organization.tld> 2000092000 +0100
+data 2
+L
+from :6
+M 100644 :7 moduleA/keepme
+
+commit refs/heads/master
+mark :9
+author Full Name <user@organization.tld> 2000099000 +0100
+committer Full Name <user@organization.tld> 2000099000 +0100
+data 29
+P: Merge commit 'M' into 'N'
+from :2
+merge :8
+
+blob
+mark :10
+data 10
+keepme v4
+
+commit refs/heads/master
+mark :11
+author Full Name <user@organization.tld> 3000000000 +0100
+committer Full Name <user@organization.tld> 3000000000 +0100
+data 2
+Q
+from :9
+M 100644 :10 moduleA/keepme
+
+blob
+mark :12
+data 10
+keepme v5
+
+commit refs/heads/master
+mark :13
+author Full Name <user@organization.tld> 3000030000 +0100
+committer Full Name <user@organization.tld> 3000030000 +0100
+data 2
+T
+from :11
+M 100644 :12 moduleA/keepme
+
+blob
+mark :14
+data 10
+keepme v6
+
+commit refs/heads/master
+mark :15
+author Full Name <user@organization.tld> 3000060000 +0100
+committer Full Name <user@organization.tld> 3000060000 +0100
+data 2
+W
+from :13
+M 100644 :14 moduleA/keepme
+
+done