diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 5016181fd7..d024b4fa59 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8056,6 +8056,7 @@ heap_xlog_clean(XLogReaderState *record)
 	xl_heap_clean *xlrec = (xl_heap_clean *) XLogRecGetData(record);
 	Buffer		buffer;
 	Size		freespace = 0;
+	bool		know_freespace = false;
 	RelFileNode rnode;
 	BlockNumber blkno;
 	XLogRedoAction action;
@@ -8107,8 +8108,6 @@ heap_xlog_clean(XLogReaderState *record)
 								nowdead, ndead,
 								nowunused, nunused);
 
-		freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
-
 		/*
 		 * Note: we don't worry about updating the page's prunability hints.
 		 * At worst this will cause an extra prune cycle to occur soon.
@@ -8118,16 +8117,16 @@ heap_xlog_clean(XLogReaderState *record)
 		MarkBufferDirty(buffer);
 	}
 	if (BufferIsValid(buffer))
+	{
+		freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
+		know_freespace = true;
 		UnlockReleaseBuffer(buffer);
+	}
 
 	/*
-	 * Update the FSM as well.
-	 *
-	 * XXX: Don't do this if the page was restored from full page image. We
-	 * don't bother to update the FSM in that case, it doesn't need to be
-	 * totally accurate anyway.
+	 * Update the FSM as well, if we can.
 	 */
-	if (action == BLK_NEEDS_REDO)
+	if (know_freespace)
 		XLogRecordPageWithFreeSpace(rnode, blkno, freespace);
 }
 
@@ -8149,6 +8148,8 @@ heap_xlog_visible(XLogReaderState *record)
 	Page		page;
 	RelFileNode rnode;
 	BlockNumber blkno;
+	Size		space;
+	bool		know_freespace = false;
 	XLogRedoAction action;
 
 	XLogRecGetBlockTag(record, 1, &rnode, NULL, &blkno);
@@ -8201,8 +8202,31 @@ heap_xlog_visible(XLogReaderState *record)
 		 * wal_log_hints enabled.)
 		 */
 	}
+
 	if (BufferIsValid(buffer))
+	{
+		space = PageGetFreeSpace(BufferGetPage(buffer));	/* for later */
+		know_freespace = true;
 		UnlockReleaseBuffer(buffer);
+	}
+
+	/*
+	 * Since FSM is not WAL-logged and only updated heuristicaly, it easily
+	 * becomes stale in standbys.  If the standby is later promoted and runs
+	 * VACUUM, it will skip updating individual free space figures for pages
+	 * that became frozen, which is troublesome when FreeSpaceMapVacuum
+	 * propagates too optimistic free space values to upper FSM layers; later
+	 * inserters try to use such pages only to find out that they are
+	 * unusable.  This can cause long stalls when there are many such pages.
+	 *
+	 * Forestall those problems by updating FSM's idea about a page that is
+	 * becoming frozen.
+	 *
+	 * Do this regardless of full-page image being applied, since the FSM data
+	 * is not in the page anyway.
+	 */
+	if ((xlrec->flags & VISIBILITYMAP_ALL_FROZEN) && know_freespace)
+		XLogRecordPageWithFreeSpace(rnode, blkno, space);
 
 	/*
 	 * Even if we skipped the heap page update due to the LSN interlock, it's