diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fc16b257d5af..de6973aa3384 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-09-24  Martin Liska  <mliska@suse.cz>
+
+	* memory-block.h (memory_block_pool::release): Annotate with
+	valgrind that the memory is not accessible.
+
 2018-09-24  Martin Liska  <mliska@suse.cz>
 
 	PR sanitizer/85774
diff --git a/gcc/memory-block.h b/gcc/memory-block.h
index 5440428240d0..c045d2e95ab2 100644
--- a/gcc/memory-block.h
+++ b/gcc/memory-block.h
@@ -68,6 +68,11 @@ memory_block_pool::release (void *uncast_block)
   block_list *block = new (uncast_block) block_list;
   block->m_next = instance.m_blocks;
   instance.m_blocks = block;
+
+  VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
+						+ sizeof (block_list),
+						block_size
+						- sizeof (block_list)));
 }
 
 extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;