diff --git a/src/backend/partitioning/partdesc.c b/src/backend/partitioning/partdesc.c
index 5f349ad46ad..a65cc526da5 100644
--- a/src/backend/partitioning/partdesc.c
+++ b/src/backend/partitioning/partdesc.c
@@ -67,19 +67,8 @@ RelationBuildPartitionDesc(Relation rel)
 				nparts;
 	PartitionKey key = RelationGetPartitionKey(rel);
 	MemoryContext oldcxt;
-	MemoryContext rbcontext;
 	int		   *mapping;
 
-	/*
-	 * While building the partition descriptor, we create various temporary
-	 * data structures; in CLOBBER_CACHE_ALWAYS mode, at least, it's important
-	 * not to leak them, since this can get called a lot.
-	 */
-	rbcontext = AllocSetContextCreate(CurrentMemoryContext,
-									  "RelationBuildPartitionDesc",
-									  ALLOCSET_DEFAULT_SIZES);
-	oldcxt = MemoryContextSwitchTo(rbcontext);
-
 	/*
 	 * Get partition oids from pg_inherits.  This uses a single snapshot to
 	 * fetch the list of children, so while more children may be getting
@@ -197,14 +186,15 @@ RelationBuildPartitionDesc(Relation rel)
 	/* If there are no partitions, the rest of the partdesc can stay zero */
 	if (nparts > 0)
 	{
-		/* Create PartitionBoundInfo, using the temporary context. */
+		/* Create PartitionBoundInfo, using the caller's context. */
 		boundinfo = partition_bounds_create(boundspecs, nparts, key, &mapping);
 
 		/* Now copy all info into relcache's partdesc. */
-		MemoryContextSwitchTo(rel->rd_pdcxt);
+		oldcxt = MemoryContextSwitchTo(rel->rd_pdcxt);
 		partdesc->boundinfo = partition_bounds_copy(boundinfo, key);
 		partdesc->oids = (Oid *) palloc(nparts * sizeof(Oid));
 		partdesc->is_leaf = (bool *) palloc(nparts * sizeof(bool));
+		MemoryContextSwitchTo(oldcxt);
 
 		/*
 		 * Assign OIDs from the original array into mapped indexes of the
@@ -214,9 +204,8 @@ RelationBuildPartitionDesc(Relation rel)
 		 *
 		 * Also record leaf-ness of each partition.  For this we use
 		 * get_rel_relkind() which may leak memory, so be sure to run it in
-		 * the temporary context.
+		 * the caller's context.
 		 */
-		MemoryContextSwitchTo(rbcontext);
 		for (i = 0; i < nparts; i++)
 		{
 			int			index = mapping[i];
@@ -228,10 +217,6 @@ RelationBuildPartitionDesc(Relation rel)
 	}
 
 	rel->rd_partdesc = partdesc;
-
-	/* Return to caller's context, and blow away the temporary context. */
-	MemoryContextSwitchTo(oldcxt);
-	MemoryContextDelete(rbcontext);
 }
 
 /*
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index eba77491fd5..84609e07253 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -93,6 +93,19 @@
 
 #define RELCACHE_INIT_FILEMAGIC		0x573266	/* version ID value */
 
+/*
+ * Default policy for whether to apply RECOVER_RELATION_BUILD_MEMORY:
+ * do so in clobber-cache builds but not otherwise.  This choice can be
+ * overridden at compile time with -DRECOVER_RELATION_BUILD_MEMORY=1 or =0.
+ */
+#ifndef RECOVER_RELATION_BUILD_MEMORY
+#if defined(CLOBBER_CACHE_ALWAYS) || defined(CLOBBER_CACHE_RECURSIVELY)
+#define RECOVER_RELATION_BUILD_MEMORY 1
+#else
+#define RECOVER_RELATION_BUILD_MEMORY 0
+#endif
+#endif
+
 /*
  *		hardcoded tuple descriptors, contents generated by genbki.pl
  */
@@ -1014,6 +1027,28 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 	HeapTuple	pg_class_tuple;
 	Form_pg_class relp;
 
+	/*
+	 * This function and its subroutines can allocate a good deal of transient
+	 * data in CurrentMemoryContext.  Traditionally we've just leaked that
+	 * data, reasoning that the caller's context is at worst of transaction
+	 * scope, and relcache loads shouldn't happen so often that it's essential
+	 * to recover transient data before end of statement/transaction.  However
+	 * that's definitely not true in clobber-cache test builds, and perhaps
+	 * it's not true in other cases.  If RECOVER_RELATION_BUILD_MEMORY is not
+	 * zero, arrange to allocate the junk in a temporary context that we'll
+	 * free before returning.  Make it a child of caller's context so that it
+	 * will get cleaned up appropriately if we error out partway through.
+	 */
+#if RECOVER_RELATION_BUILD_MEMORY
+	MemoryContext tmpcxt;
+	MemoryContext oldcxt;
+
+	tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
+								   "RelationBuildDesc workspace",
+								   ALLOCSET_DEFAULT_SIZES);
+	oldcxt = MemoryContextSwitchTo(tmpcxt);
+#endif
+
 	/*
 	 * find the tuple in pg_class corresponding to the given relation id
 	 */
@@ -1023,7 +1058,14 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 	 * if no such tuple exists, return NULL
 	 */
 	if (!HeapTupleIsValid(pg_class_tuple))
+	{
+#if RECOVER_RELATION_BUILD_MEMORY
+		/* Return to caller's context, and blow away the temporary context */
+		MemoryContextSwitchTo(oldcxt);
+		MemoryContextDelete(tmpcxt);
+#endif
 		return NULL;
+	}
 
 	/*
 	 * get information from the pg_class_tuple
@@ -1203,6 +1245,12 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 	/* It's fully valid */
 	relation->rd_isvalid = true;
 
+#if RECOVER_RELATION_BUILD_MEMORY
+	/* Return to caller's context, and blow away the temporary context */
+	MemoryContextSwitchTo(oldcxt);
+	MemoryContextDelete(tmpcxt);
+#endif
+
 	return relation;
 }