diff --git a/hgext/convert/p4.py b/hgext/convert/p4.py
--- a/hgext/convert/p4.py
+++ b/hgext/convert/p4.py
@@ -55,6 +55,7 @@ class p4_source(common.converter_source)
 
         common.checktool('p4', abort=False)
 
+        self.revmap = {}
         self.p4changes = {}
         self.heads = []
         self.changeset = {}
@@ -77,6 +78,19 @@ class p4_source(common.converter_source)
                                "multiple revisions"))
         self._parse(ui, path)
 
+    def setrevmap(self, revmap):
+        """Sets the parsed revmap dictionary.
+
+        Revmap stores mappings from a source revision to a target revision.
+        It is set in convertcmd.convert and provided by the user as a file
+        on the commandline.
+
+        Revisions in the map are considered beeing present in the
+        repository and ignored during _parse(). This allows for incremental
+        imports if a revmap is provided.
+        """
+        self.revmap = revmap
+
     def _parse_view(self, path):
         "Read changes affecting the path"
         cmd = 'p4 -G changes -s submitted %s' % util.shellquote(path)
@@ -132,6 +146,10 @@ class p4_source(common.converter_source)
                 continue
             if self.revs and int(change) > int(self.revs[0]):
                 continue
+            if change in self.revmap:
+                # Ignore already present revisions, but set the parent pointer.
+                lastid = change
+                continue
 
             cmd = "p4 -G describe -s %s" % change
             stdout = util.popen(cmd, mode='rb')