diff --git a/contrib/simplemerge b/contrib/simplemerge
--- a/contrib/simplemerge
+++ b/contrib/simplemerge
@@ -106,11 +106,16 @@
     except error.Abort:
         sys.exit(1)
 
-    sys.exit(
-        simplemerge.simplemerge(
-            ui, local_input, base_input, other_input, **opts
-        )
+    merged_text, conflicts = simplemerge.simplemerge(
+        ui, local_input, base_input, other_input, **opts
     )
+    if merged_text is not None:
+        if opts['print']:
+            ui.fout.write(merged_text)
+        else:
+            with open(local, 'wb') as f:
+                f.write(merged_text)
+    sys.exit(1 if conflicts else 0)
 except ParseError as e:
     e = stringutil.forcebytestr(e)
     procutil.stdout.write(b"%s: %s\n" % (sys.argv[0].encode('utf8'), e))
diff --git a/mercurial/filemerge.py b/mercurial/filemerge.py
--- a/mercurial/filemerge.py
+++ b/mercurial/filemerge.py
@@ -434,12 +434,18 @@
             base.verifytext(ui, quiet=True)
             other.verifytext(ui, quiet=True)
         except error.Abort:
-            r = True
+            return 1
         else:
-            r = simplemerge.simplemerge(ui, local, base, other, mode=mode)
-        if not r:
-            ui.debug(b" premerge successful\n")
-            return 0
+            merged_text, conflicts = simplemerge.simplemerge(
+                ui, local, base, other, mode=mode
+            )
+            # fcd.flags() already has the merged flags (done in
+            # mergestate.resolve())
+            if merged_text is not None:
+                local.fctx.write(merged_text, local.fctx.flags())
+            if not conflicts:
+                ui.debug(b" premerge successful\n")
+                return 0
         if premerge not in validkeep:
             # restore from backup and try again
             _restorebackup(local.fctx, backup)
@@ -480,10 +486,16 @@
         base.verifytext(ui)
         other.verifytext(ui)
     except error.Abort:
-        r = True
+        conflicts = True
     else:
-        r = simplemerge.simplemerge(ui, local, base, other, mode=mode)
-    return True, r, False
+        merged_text, conflicts = simplemerge.simplemerge(
+            ui, local, base, other, mode=mode
+        )
+        # fcd.flags() already has the merged flags (done in
+        # mergestate.resolve())
+        if merged_text is not None:
+            local.fctx.write(merged_text, local.fctx.flags())
+    return True, conflicts, False
 
 
 @internaltool(
diff --git a/mercurial/simplemerge.py b/mercurial/simplemerge.py
--- a/mercurial/simplemerge.py
+++ b/mercurial/simplemerge.py
@@ -522,11 +522,4 @@
             lines, conflicts = render_minimized(m3, *labels)
 
     mergedtext = b''.join(lines)
-    if opts.get('print'):
-        ui.fout.write(mergedtext)
-    else:
-        # local.fctx.flags() already has the merged flags (done in
-        # mergestate.resolve())
-        local.fctx.write(mergedtext, local.fctx.flags())
-
-    return conflicts
+    return mergedtext, conflicts