diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -1165,15 +1165,19 @@ def add(ui, repo, match, dryrun, listsub
             if ui.verbose or not exact:
                 ui.status(_('adding %s\n') % match.rel(join(f)))
 
-    if listsubrepos:
-        for subpath in wctx.substate:
-            sub = wctx.sub(subpath)
-            try:
-                submatch = matchmod.narrowmatcher(subpath, match)
+    for subpath in wctx.substate:
+        sub = wctx.sub(subpath)
+        try:
+            submatch = matchmod.narrowmatcher(subpath, match)
+            if listsubrepos:
                 bad.extend(sub.add(ui, submatch, dryrun, prefix))
-            except error.LookupError:
-                ui.status(_("skipping missing subrepository: %s\n")
-                               % join(subpath))
+            else:
+                for f in sub.walk(submatch):
+                    if submatch.exact(f):
+                        bad.extend(sub.add(ui, submatch, dryrun, prefix))
+        except error.LookupError:
+            ui.status(_("skipping missing subrepository: %s\n")
+                           % join(subpath))
 
     if not dryrun:
         rejected = wctx.add(names, prefix)
diff --git a/mercurial/help/subrepos.txt b/mercurial/help/subrepos.txt
--- a/mercurial/help/subrepos.txt
+++ b/mercurial/help/subrepos.txt
@@ -73,7 +73,9 @@ Interaction with Mercurial Commands
 -----------------------------------
 
 :add: add does not recurse in subrepos unless -S/--subrepos is
-    specified. Subversion subrepositories are currently silently
+    specified.  However, if you specify the full path of a file in a
+    subrepo, it will be added even without -S/--subrepos specified.
+    Subversion subrepositories are currently silently
     ignored.
 
 :archive: archive does not recurse in subrepositories unless
diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -353,6 +353,12 @@ class abstractsubrepo(object):
                         unit=_('files'), total=total)
         ui.progress(_('archiving (%s)') % relpath, None)
 
+    def walk(self, match):
+        '''
+        walk recursively through the directory tree, finding all files
+        matched by the match function
+        '''
+        pass
 
 class hgsubrepo(abstractsubrepo):
     def __init__(self, ctx, path, state):
@@ -543,6 +549,9 @@ class hgsubrepo(abstractsubrepo):
         ctx = self._repo[rev]
         return ctx.flags(name)
 
+    def walk(self, match):
+        ctx = self._repo[None]
+        return ctx.walk(match)
 
 class svnsubrepo(abstractsubrepo):
     def __init__(self, ctx, path, state):
diff --git a/tests/test-subrepo.t b/tests/test-subrepo.t
--- a/tests/test-subrepo.t
+++ b/tests/test-subrepo.t
@@ -892,7 +892,7 @@ Test behavior of add for explicit path i
   $ hg init s
   $ hg ci -m0
   committing subrepository s
-Adding with an explicit path in a subrepo currently fails silently
+Adding with an explicit path in a subrepo adds the file
   $ echo c1 > f1
   $ echo c2 > s/f2
   $ hg st -S
@@ -900,14 +900,13 @@ Adding with an explicit path in a subrep
   ? s/f2
   $ hg add s/f2
   $ hg st -S
+  A s/f2
   ? f1
-  ? s/f2
-  $ hg ci -R s -Am0
-  adding f2
+  $ hg ci -R s -m0
   $ hg ci -Am1
   adding f1
   committing subrepository s
-Adding with an explicit path in a subrepo with -S adds the file
+Adding with an explicit path in a subrepo with -S has the same behavior
   $ echo c3 > f3
   $ echo c4 > s/f4
   $ hg st -S