diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index 8d0903c175..acd5c2431d 100644
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -452,7 +452,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
 	if (XLogArchivingActive())
 	{
 		TLHistoryFileName(histfname, newTLI);
-		XLogArchiveNotify(histfname);
+		XLogArchiveNotify(histfname, true);
 	}
 }
 
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e51a7a749d..24165ab03e 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -724,6 +724,18 @@ typedef struct XLogCtlData
 	XLogRecPtr	lastFpwDisableRecPtr;
 
 	slock_t		info_lck;		/* locks shared variables shown above */
+
+	/*
+	 * Variables used to track segment-boundary-crossing WAL records.  See
+	 * RegisterSegmentBoundary.  Protected by segtrack_lck.
+	 */
+	XLogSegNo	lastNotifiedSeg;
+	XLogSegNo	earliestSegBoundary;
+	XLogRecPtr	earliestSegBoundaryEndPtr;
+	XLogSegNo	latestSegBoundary;
+	XLogRecPtr	latestSegBoundaryEndPtr;
+
+	slock_t		segtrack_lck;	/* locks shared variables shown above */
 } XLogCtlData;
 
 static XLogCtlData *XLogCtl = NULL;
@@ -920,6 +932,7 @@ static void RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo,
 						   XLogSegNo *endlogSegNo);
 static void UpdateLastRemovedPtr(char *filename);
 static void ValidateXLOGDirectoryStructure(void);
+static void RegisterSegmentBoundary(XLogSegNo seg, XLogRecPtr pos);
 static void CleanupBackupHistory(void);
 static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force);
 static XLogRecord *ReadRecord(XLogReaderState *xlogreader,
@@ -1154,23 +1167,56 @@ XLogInsertRecord(XLogRecData *rdata,
 	END_CRIT_SECTION();
 
 	/*
-	 * Update shared LogwrtRqst.Write, if we crossed page boundary.
+	 * If we crossed page boundary, update LogwrtRqst.Write; if we crossed
+	 * segment boundary, register that and wake up walwriter.
 	 */
 	if (StartPos / XLOG_BLCKSZ != EndPos / XLOG_BLCKSZ)
 	{
+		XLogSegNo	StartSeg;
+		XLogSegNo	EndSeg;
+
+		XLByteToSeg(StartPos, StartSeg, wal_segment_size);
+		XLByteToSeg(EndPos, EndSeg, wal_segment_size);
+
+		/*
+		 * Register our crossing the segment boundary if that occurred.
+		 *
+		 * Note that we did not use XLByteToPrevSeg() for determining the
+		 * ending segment.  This is so that a record that fits perfectly into
+		 * the end of the segment causes the latter to get marked ready for
+		 * archival immediately.
+		 */
+		if (StartSeg != EndSeg && XLogArchivingActive())
+			RegisterSegmentBoundary(EndSeg, EndPos);
+
+		/*
+		 * Advance LogwrtRqst.Write so that it includes new block(s).
+		 *
+		 * We do this after registering the segment boundary so that the
+		 * comparison with the flushed pointer below can use the latest value
+		 * known globally.
+		 */
 		SpinLockAcquire(&XLogCtl->info_lck);
-		/* advance global request to include new block(s) */
 		if (XLogCtl->LogwrtRqst.Write < EndPos)
 			XLogCtl->LogwrtRqst.Write = EndPos;
 		/* update local result copy while I have the chance */
 		LogwrtResult = XLogCtl->LogwrtResult;
 		SpinLockRelease(&XLogCtl->info_lck);
+
+		/*
+		 * There's a chance that the record was already flushed to disk and we
+		 * missed marking segments as ready for archive.  If this happens, we
+		 * nudge the WALWriter, which will take care of notifying segments as
+		 * needed.
+		 */
+		if (StartSeg != EndSeg && XLogArchivingActive() &&
+			LogwrtResult.Flush >= EndPos && ProcGlobal->walwriterLatch)
+			SetLatch(ProcGlobal->walwriterLatch);
 	}
 
 	/*
 	 * If this was an XLOG_SWITCH record, flush the record and the empty
-	 * padding space that fills the rest of the segment, and perform
-	 * end-of-segment actions (eg, notifying archiver).
+	 * padding space that fills the rest of the segment.
 	 */
 	if (isLogSwitch)
 	{
@@ -2421,6 +2467,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
 
 	/* We should always be inside a critical section here */
 	Assert(CritSectionCount > 0);
+	Assert(LWLockHeldByMe(WALWriteLock));
 
 	/*
 	 * Update local LogwrtResult (caller probably did this already, but...)
@@ -2586,11 +2633,12 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
 			 * later. Doing it here ensures that one and only one backend will
 			 * perform this fsync.
 			 *
-			 * This is also the right place to notify the Archiver that the
-			 * segment is ready to copy to archival storage, and to update the
-			 * timer for archive_timeout, and to signal for a checkpoint if
-			 * too many logfile segments have been used since the last
-			 * checkpoint.
+			 * If WAL archiving is active, we attempt to notify the archiver
+			 * of any segments that are now ready for archival.
+			 *
+			 * This is also the right place to update the timer for
+			 * archive_timeout and to signal for a checkpoint if too many
+			 * logfile segments have been used since the last checkpoint.
 			 */
 			if (finishing_seg)
 			{
@@ -2602,7 +2650,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
 				LogwrtResult.Flush = LogwrtResult.Write;	/* end of page */
 
 				if (XLogArchivingActive())
-					XLogArchiveNotifySeg(openLogSegNo);
+					NotifySegmentsReadyForArchive(LogwrtResult.Flush);
 
 				XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL);
 				XLogCtl->lastSegSwitchLSN = LogwrtResult.Flush;
@@ -2690,6 +2738,9 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
 			XLogCtl->LogwrtRqst.Flush = LogwrtResult.Flush;
 		SpinLockRelease(&XLogCtl->info_lck);
 	}
+
+	if (XLogArchivingActive())
+		NotifySegmentsReadyForArchive(LogwrtResult.Flush);
 }
 
 /*
@@ -4328,6 +4379,131 @@ ValidateXLOGDirectoryStructure(void)
 	}
 }
 
+/*
+ * RegisterSegmentBoundary
+ *
+ * WAL records that are split across a segment boundary require special
+ * treatment for archiving: the initial segment must not be archived until
+ * the end segment has been flushed, in case we crash before we have
+ * the chance to flush the end segment (because after recovery we would
+ * overwrite that WAL record with a different one, and so the file we
+ * archived no longer represents truth.)  This also applies to streaming
+ * physical replication.
+ *
+ * To handle this, we keep track of the LSN of WAL records that cross
+ * segment boundaries.  Two such are sufficient: the ones with the
+ * earliest and the latest end pointers we know about, since the flush
+ * position advances monotonically.  WAL record writers register
+ * boundary-crossing records here, which is used by .ready file creation
+ * to delay until the end segment is known flushed.
+ */
+static void
+RegisterSegmentBoundary(XLogSegNo seg, XLogRecPtr endpos)
+{
+	XLogSegNo	segno PG_USED_FOR_ASSERTS_ONLY;
+
+	/* verify caller computed segment number correctly */
+	AssertArg((XLByteToSeg(endpos, segno, wal_segment_size), segno == seg));
+
+	SpinLockAcquire(&XLogCtl->segtrack_lck);
+
+	/*
+	 * If no segment boundaries are registered, store the new segment boundary
+	 * in earliestSegBoundary.  Otherwise, store the greater segment
+	 * boundaries in latestSegBoundary.
+	 */
+	if (XLogCtl->earliestSegBoundary == MaxXLogSegNo)
+	{
+		XLogCtl->earliestSegBoundary = seg;
+		XLogCtl->earliestSegBoundaryEndPtr = endpos;
+	}
+	else if (seg > XLogCtl->earliestSegBoundary &&
+			 (XLogCtl->latestSegBoundary == MaxXLogSegNo ||
+			  seg > XLogCtl->latestSegBoundary))
+	{
+		XLogCtl->latestSegBoundary = seg;
+		XLogCtl->latestSegBoundaryEndPtr = endpos;
+	}
+
+	SpinLockRelease(&XLogCtl->segtrack_lck);
+}
+
+/*
+ * NotifySegmentsReadyForArchive
+ *
+ * Mark segments as ready for archival, given that it is safe to do so.
+ * This function is idempotent.
+ */
+void
+NotifySegmentsReadyForArchive(XLogRecPtr flushRecPtr)
+{
+	XLogSegNo	latest_boundary_seg;
+	XLogSegNo	last_notified;
+	XLogSegNo	flushed_seg;
+	XLogSegNo	seg;
+	bool		keep_latest;
+
+	XLByteToSeg(flushRecPtr, flushed_seg, wal_segment_size);
+
+	SpinLockAcquire(&XLogCtl->segtrack_lck);
+
+	if (XLogCtl->latestSegBoundary <= flushed_seg &&
+		XLogCtl->latestSegBoundaryEndPtr <= flushRecPtr)
+	{
+		latest_boundary_seg = XLogCtl->latestSegBoundary;
+		keep_latest = false;
+	}
+	else if (XLogCtl->earliestSegBoundary <= flushed_seg &&
+			 XLogCtl->earliestSegBoundaryEndPtr <= flushRecPtr)
+	{
+		latest_boundary_seg = XLogCtl->earliestSegBoundary;
+		keep_latest = true;
+	}
+	else
+	{
+		SpinLockRelease(&XLogCtl->segtrack_lck);
+		return;
+	}
+
+	last_notified = XLogCtl->lastNotifiedSeg;
+
+	/*
+	 * Update shared memory and discard segment boundaries that are no longer
+	 * needed.
+	 *
+	 * It is safe to update shared memory before we attempt to create the
+	 * .ready files.  If our calls to XLogArchiveNotifySeg() fail,
+	 * RemoveOldXlogFiles() will retry it as needed.
+	 */
+	if (last_notified < latest_boundary_seg - 1)
+		XLogCtl->lastNotifiedSeg = latest_boundary_seg - 1;
+
+	if (keep_latest)
+	{
+		XLogCtl->earliestSegBoundary = XLogCtl->latestSegBoundary;
+		XLogCtl->earliestSegBoundaryEndPtr = XLogCtl->latestSegBoundaryEndPtr;
+	}
+	else
+	{
+		XLogCtl->earliestSegBoundary = MaxXLogSegNo;
+		XLogCtl->earliestSegBoundaryEndPtr = InvalidXLogRecPtr;
+	}
+
+	XLogCtl->latestSegBoundary = MaxXLogSegNo;
+	XLogCtl->latestSegBoundaryEndPtr = InvalidXLogRecPtr;
+
+	SpinLockRelease(&XLogCtl->segtrack_lck);
+
+	/*
+	 * Notify archiver about segments that are ready for archival (by creating
+	 * the corresponding .ready files).
+	 */
+	for (seg = last_notified + 1; seg < latest_boundary_seg; seg++)
+		XLogArchiveNotifySeg(seg, false);
+
+	PgArchWakeup();
+}
+
 /*
  * Remove previous backup history files.  This also retries creation of
  * .ready files for any backup history files for which XLogArchiveNotify
@@ -5230,9 +5406,17 @@ XLOGShmemInit(void)
 
 	SpinLockInit(&XLogCtl->Insert.insertpos_lck);
 	SpinLockInit(&XLogCtl->info_lck);
+	SpinLockInit(&XLogCtl->segtrack_lck);
 	SpinLockInit(&XLogCtl->ulsn_lck);
 	InitSharedLatch(&XLogCtl->recoveryWakeupLatch);
 	ConditionVariableInit(&XLogCtl->recoveryNotPausedCV);
+
+	/* Initialize stuff for marking segments as ready for archival. */
+	XLogCtl->lastNotifiedSeg = MaxXLogSegNo;
+	XLogCtl->earliestSegBoundary = MaxXLogSegNo;
+	XLogCtl->earliestSegBoundaryEndPtr = InvalidXLogRecPtr;
+	XLogCtl->latestSegBoundary = MaxXLogSegNo;
+	XLogCtl->latestSegBoundaryEndPtr = InvalidXLogRecPtr;
 }
 
 /*
@@ -7873,6 +8057,20 @@ StartupXLOG(void)
 	XLogCtl->LogwrtRqst.Write = EndOfLog;
 	XLogCtl->LogwrtRqst.Flush = EndOfLog;
 
+	/*
+	 * Initialize XLogCtl->lastNotifiedSeg to the previous WAL file.
+	 */
+	if (XLogArchivingActive())
+	{
+		XLogSegNo	EndOfLogSeg;
+
+		XLByteToSeg(EndOfLog, EndOfLogSeg, wal_segment_size);
+
+		SpinLockAcquire(&XLogCtl->segtrack_lck);
+		XLogCtl->lastNotifiedSeg = EndOfLogSeg - 1;
+		SpinLockRelease(&XLogCtl->segtrack_lck);
+	}
+
 	/*
 	 * Update full_page_writes in shared memory and write an XLOG_FPW_CHANGE
 	 * record before resource manager writes cleanup WAL records or checkpoint
@@ -8000,7 +8198,7 @@ StartupXLOG(void)
 				XLogArchiveCleanup(partialfname);
 
 				durable_rename(origpath, partialpath, ERROR);
-				XLogArchiveNotify(partialfname);
+				XLogArchiveNotify(partialfname, true);
 			}
 		}
 	}
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 26b023e754..b9c19b2085 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -433,7 +433,7 @@ KeepFileRestoredFromArchive(const char *path, const char *xlogfname)
 	if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 		XLogArchiveForceDone(xlogfname);
 	else
-		XLogArchiveNotify(xlogfname);
+		XLogArchiveNotify(xlogfname, true);
 
 	/*
 	 * If the existing file was replaced, since walsenders might have it open,
@@ -462,9 +462,12 @@ KeepFileRestoredFromArchive(const char *path, const char *xlogfname)
  * by the archiver, e.g. we write 0000000100000001000000C6.ready
  * and the archiver then knows to archive XLOGDIR/0000000100000001000000C6,
  * then when complete, rename it to 0000000100000001000000C6.done
+ *
+ * Optionally, nudge the archiver process so that it'll notice the file we
+ * create.
  */
 void
-XLogArchiveNotify(const char *xlog)
+XLogArchiveNotify(const char *xlog, bool nudge)
 {
 	char		archiveStatusPath[MAXPGPATH];
 	FILE	   *fd;
@@ -489,8 +492,8 @@ XLogArchiveNotify(const char *xlog)
 		return;
 	}
 
-	/* Notify archiver that it's got something to do */
-	if (IsUnderPostmaster)
+	/* If caller requested, let archiver know it's got work to do */
+	if (nudge)
 		PgArchWakeup();
 }
 
@@ -498,12 +501,12 @@ XLogArchiveNotify(const char *xlog)
  * Convenience routine to notify using segment number representation of filename
  */
 void
-XLogArchiveNotifySeg(XLogSegNo segno)
+XLogArchiveNotifySeg(XLogSegNo segno, bool nudge)
 {
 	char		xlog[MAXFNAMELEN];
 
 	XLogFileName(xlog, ThisTimeLineID, segno, wal_segment_size);
-	XLogArchiveNotify(xlog);
+	XLogArchiveNotify(xlog, nudge);
 }
 
 /*
@@ -608,7 +611,7 @@ XLogArchiveCheckDone(const char *xlog)
 		return true;
 
 	/* Retry creation of the .ready file */
-	XLogArchiveNotify(xlog);
+	XLogArchiveNotify(xlog, true);
 	return false;
 }
 
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 626fae8454..6a1e16edc2 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -248,6 +248,13 @@ WalWriterMain(void)
 		/* Process any signals received recently */
 		HandleWalWriterInterrupts();
 
+		/*
+		 * Notify the archiver of any WAL segments that are ready.  We do this
+		 * here to handle a race condition where WAL is flushed to disk prior
+		 * to registering the segment boundary.
+		 */
+		NotifySegmentsReadyForArchive(GetFlushRecPtr());
+
 		/*
 		 * Do what we're here for; then, if XLogBackgroundFlush() found useful
 		 * work to do, reset hibernation counter.
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 9a2bc37fd7..60de3be92c 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -622,7 +622,7 @@ WalReceiverMain(void)
 			if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 				XLogArchiveForceDone(xlogfname);
 			else
-				XLogArchiveNotify(xlogfname);
+				XLogArchiveNotify(xlogfname, true);
 		}
 		recvFile = -1;
 
@@ -760,7 +760,7 @@ WalRcvFetchTimeLineHistoryFiles(TimeLineID first, TimeLineID last)
 			if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 				XLogArchiveForceDone(fname);
 			else
-				XLogArchiveNotify(fname);
+				XLogArchiveNotify(fname, true);
 
 			pfree(fname);
 			pfree(content);
@@ -915,7 +915,7 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 				if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 					XLogArchiveForceDone(xlogfname);
 				else
-					XLogArchiveNotify(xlogfname);
+					XLogArchiveNotify(xlogfname, true);
 			}
 			recvFile = -1;
 
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 0a8ede700d..6b6ae81c2d 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -315,6 +315,7 @@ extern XLogRecPtr GetInsertRecPtr(void);
 extern XLogRecPtr GetFlushRecPtr(void);
 extern XLogRecPtr GetLastImportantRecPtr(void);
 extern void RemovePromoteSignalFiles(void);
+extern void NotifySegmentsReadyForArchive(XLogRecPtr flushRecPtr);
 
 extern bool PromoteIsTriggered(void);
 extern bool CheckPromoteSignal(void);
diff --git a/src/include/access/xlogarchive.h b/src/include/access/xlogarchive.h
index 3edd1a976c..935b4cb02d 100644
--- a/src/include/access/xlogarchive.h
+++ b/src/include/access/xlogarchive.h
@@ -23,8 +23,8 @@ extern bool RestoreArchivedFile(char *path, const char *xlogfname,
 extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
 								   bool failOnSignal);
 extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
-extern void XLogArchiveNotify(const char *xlog);
-extern void XLogArchiveNotifySeg(XLogSegNo segno);
+extern void XLogArchiveNotify(const char *xlog, bool nudge);
+extern void XLogArchiveNotifySeg(XLogSegNo segno, bool nudge);
 extern void XLogArchiveForceDone(const char *xlog);
 extern bool XLogArchiveCheckDone(const char *xlog);
 extern bool XLogArchiveIsBusy(const char *xlog);
diff --git a/src/include/access/xlogdefs.h b/src/include/access/xlogdefs.h
index 60348d1850..9b455e88e3 100644
--- a/src/include/access/xlogdefs.h
+++ b/src/include/access/xlogdefs.h
@@ -46,6 +46,7 @@ typedef uint64 XLogRecPtr;
  * XLogSegNo - physical log file sequence number.
  */
 typedef uint64 XLogSegNo;
+#define MaxXLogSegNo	((XLogSegNo) 0xFFFFFFFFFFFFFFFF)
 
 /*
  * TimeLineID (TLI) - identifies different database histories to prevent