diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 4060e600ff..69b6ef352b 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -35,6 +35,7 @@
 #include "access/clog.h"
 #include "access/slru.h"
 #include "access/transam.h"
+#include "miscadmin.h"
 #include "pg_trace.h"
 
 /*
@@ -409,6 +410,34 @@ TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn)
 	return status;
 }
 
+/*
+ * Number of shared CLOG buffers.
+ *
+ * Testing during the PostgreSQL 9.2 development cycle revealed that on a
+ * large multi-processor system, it was possible to have more CLOG page
+ * requests in flight at one time than the numebr of CLOG buffers which existed
+ * at that time, which was hardcoded to 8.  Further testing revealed that
+ * performance dropped off with more than 32 CLOG buffers, possibly because
+ * the linear buffer search algorithm doesn't scale well.
+ *
+ * Unconditionally increasing the number of CLOG buffers to 32 did not seem
+ * like a good idea, because it would increase the minimum amount of shared
+ * memory required to start, which could be a problem for people running very
+ * small configurations.  The following formula seems to represent a reasonable
+ * compromise: people with very low values for shared_buffers will get fewer
+ * CLOG buffers as well, and everyone else will get 32.
+ *
+ * It is likely that some further work will be needed here in future releases;
+ * for example, on a 64-core server, the maximum number of CLOG requests that
+ * can be simultaneously in flight will be even larger.  But that will
+ * apparently require more than just changing the formula, so for now we take
+ * the easy way out.
+ */
+Size
+CLOGShmemBuffers(void)
+{
+	return Min(32, Max(4, NBuffers / 512));
+}
 
 /*
  * Initialization of shared memory for CLOG
@@ -416,14 +445,14 @@ TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn)
 Size
 CLOGShmemSize(void)
 {
-	return SimpleLruShmemSize(NUM_CLOG_BUFFERS, CLOG_LSNS_PER_PAGE);
+	return SimpleLruShmemSize(CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE);
 }
 
 void
 CLOGShmemInit(void)
 {
 	ClogCtl->PagePrecedes = CLOGPagePrecedes;
-	SimpleLruInit(ClogCtl, "CLOG Ctl", NUM_CLOG_BUFFERS, CLOG_LSNS_PER_PAGE,
+	SimpleLruInit(ClogCtl, "CLOG Ctl", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE,
 				  CLogControlLock, "pg_clog");
 }
 
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 96f0d3822e..cc4156826b 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -171,7 +171,7 @@ NumLWLocks(void)
 	numLocks += MaxBackends + NUM_AUXILIARY_PROCS;
 
 	/* clog.c needs one per CLOG buffer */
-	numLocks += NUM_CLOG_BUFFERS;
+	numLocks += CLOGShmemBuffers();
 
 	/* subtrans.c needs one per SubTrans buffer */
 	numLocks += NUM_SUBTRANS_BUFFERS;
diff --git a/src/include/access/clog.h b/src/include/access/clog.h
index 9cf54a4486..bed3b8cf26 100644
--- a/src/include/access/clog.h
+++ b/src/include/access/clog.h
@@ -28,14 +28,11 @@ typedef int XidStatus;
 #define TRANSACTION_STATUS_SUB_COMMITTED	0x03
 
 
-/* Number of SLRU buffers to use for clog */
-#define NUM_CLOG_BUFFERS	8
-
-
 extern void TransactionIdSetTreeStatus(TransactionId xid, int nsubxids,
 				   TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
 extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);
 
+extern Size CLOGShmemBuffers(void);
 extern Size CLOGShmemSize(void);
 extern void CLOGShmemInit(void);
 extern void BootStrapCLOG(void);