diff --git a/sys/dev/bge/if_bge.c b/sys/dev/bge/if_bge.c
index 8ca0c734d690..b42d44f9135e 100644
--- a/sys/dev/bge/if_bge.c
+++ b/sys/dev/bge/if_bge.c
@@ -483,12 +483,29 @@ DRIVER_MODULE(bge, pci, bge_driver, bge_devclass, 0, 0);
 DRIVER_MODULE(miibus, bge, miibus_driver, miibus_devclass, 0, 0);
 
 static int bge_allow_asf = 1;
+/*
+ * A common design characteristic for many Broadcom client controllers
+ * is that they only support a single outstanding DMA read operation
+ * on the PCIe bus. This means that it will take twice as long to fetch
+ * a TX frame that is split into header and payload buffers as it does
+ * to fetch a single, contiguous TX frame (2 reads vs. 1 read). For
+ * these controllers, coalescing buffers to reduce the number of memory
+ * reads is effective way to get maximum performance(about 940Mbps).
+ * Without collapsing TX buffers the maximum TCP bulk transfer
+ * performance is about 850Mbps. However forcing coalescing mbufs
+ * consumes a lot of CPU cycles, so leave it off by default.
+ */
+static int bge_forced_collapse = 0;
 
 TUNABLE_INT("hw.bge.allow_asf", &bge_allow_asf);
+TUNABLE_INT("hw.bge.forced_collapse", &bge_forced_collapse);
 
 SYSCTL_NODE(_hw, OID_AUTO, bge, CTLFLAG_RD, 0, "BGE driver parameters");
 SYSCTL_INT(_hw_bge, OID_AUTO, allow_asf, CTLFLAG_RD, &bge_allow_asf, 0,
 	"Allow ASF mode if available");
+SYSCTL_INT(_hw_bge, OID_AUTO, forced_collapse, CTLFLAG_RD, &bge_forced_collapse,
+	0, "Number of fragmented TX buffers of a frame allowed before "
+	"forced collapsing");
 
 #define	SPARC64_BLADE_1500_MODEL	"SUNW,Sun-Blade-1500"
 #define	SPARC64_BLADE_1500_PATH_BGE	"/pci@1f,700000/network@2"
@@ -3915,6 +3932,26 @@ bge_encap(struct bge_softc *sc, struct mbuf **m_head, uint32_t *txidx)
 			csum_flags |= BGE_TXBDFLAG_IP_FRAG;
 	}
 
+	if ((m->m_pkthdr.csum_flags & CSUM_TSO) == 0 &&
+	    bge_forced_collapse > 0 && (sc->bge_flags & BGE_FLAG_PCIE) != 0 &&
+	    m->m_next != NULL) {
+		/*
+		 * Forcedly collapse mbuf chains to overcome hardware
+		 * limitation which only support a single outstanding
+		 * DMA read operation.
+		 */
+		if (bge_forced_collapse == 1)
+			m = m_defrag(m, M_DONTWAIT);
+		else
+			m = m_collapse(m, M_DONTWAIT, bge_forced_collapse);
+		if (m == NULL) {
+			m_freem(*m_head);
+			*m_head = NULL;
+			return (ENOBUFS);
+		}
+		*m_head = m;
+	}
+
 	map = sc->bge_cdata.bge_tx_dmamap[idx];
 	error = bus_dmamap_load_mbuf_sg(sc->bge_cdata.bge_tx_mtag, map, m, segs,
 	    &nsegs, BUS_DMA_NOWAIT);