diff --git a/ompi/mca/mtl/portals4/mtl_portals4_cancel.c b/ompi/mca/mtl/portals4/mtl_portals4_cancel.c
new file mode 100644
index 0000000000..70a5110793
--- /dev/null
+++ b/ompi/mca/mtl/portals4/mtl_portals4_cancel.c
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2012      Sandia National Laboratories.  All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#include "ompi_config.h"
+
+#include <portals4.h>
+
+#include "mtl_portals4.h"
+#include "mtl_portals4_request.h"
+
+
+int
+ompi_mtl_portals4_cancel(struct mca_mtl_base_module_t* mtl,
+                         mca_mtl_request_t *mtl_request,
+                         int flag)
+{
+    ompi_mtl_portals4_base_request_t *base_request = 
+        (ompi_mtl_portals4_base_request_t*) mtl_request;
+    int ret;
+
+    switch (base_request->type) {
+    case portals4_req_isend:
+        /* can't cancel sends yet */
+        break;
+
+    case portals4_req_recv:
+        {
+            ompi_mtl_portals4_recv_request_t *recvreq = 
+                (ompi_mtl_portals4_recv_request_t*) base_request;
+
+            /* Cancel receive requests if not yet matched (otherwise,
+               they are guaranteed to complete and don't need to be
+               cancelled).  If the me_h is already INVALID, that means
+               that not only has matching occurred, but the
+               communication end event has been seen.  If MEUnlink
+               fails, that means that either something bad has
+               happened or the ME is in use (meaning no cancel).  Need
+               to drain queue to make sure there isn't a pending
+               receive completion event... */
+            ompi_mtl_portals4_progress();
+
+            if (PTL_INVALID_HANDLE != recvreq->me_h) {
+                ret = PtlMEUnlink(recvreq->me_h);
+                if (PTL_OK == ret) {
+                    recvreq->super.super.ompi_req->req_status._cancelled = true;
+                    recvreq->super.super.completion_callback(&recvreq->super.super);
+                }
+            }
+        }
+        break;
+
+    default:
+        return OMPI_ERROR;
+    }
+
+    return OMPI_SUCCESS;
+}
+
+
diff --git a/ompi/mca/mtl/portals4/mtl_portals4_recv.c b/ompi/mca/mtl/portals4/mtl_portals4_recv.c
index 93ba3aa99e..54dda3115c 100644
--- a/ompi/mca/mtl/portals4/mtl_portals4_recv.c
+++ b/ompi/mca/mtl/portals4/mtl_portals4_recv.c
@@ -56,6 +56,8 @@ ompi_mtl_portals4_recv_progress(ptl_event_t *ev,
             goto callback_error;
         }
 
+        ptl_request->me_h = PTL_INVALID_HANDLE;
+
         msg_length = MTL_PORTALS4_GET_LENGTH(ev->hdr_data);
         ptl_request->super.super.ompi_req->req_status.MPI_SOURCE =
             MTL_PORTALS4_GET_SOURCE(ev->match_bits);
@@ -179,6 +181,8 @@ ompi_mtl_portals4_recv_progress(ptl_event_t *ev,
             goto callback_error;
         }
 
+        ptl_request->me_h = PTL_INVALID_HANDLE;
+
         msg_length = MTL_PORTALS4_GET_LENGTH(ev->hdr_data);
         ptl_request->super.super.ompi_req->req_status.MPI_SOURCE =
             MTL_PORTALS4_GET_SOURCE(ev->match_bits);