diff --git a/include/rocksdb/file_system.h b/include/rocksdb/file_system.h
index 20f51f51e..fb105bc6c 100644
--- a/include/rocksdb/file_system.h
+++ b/include/rocksdb/file_system.h
@@ -25,6 +25,7 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 #include "rocksdb/env.h"
@@ -90,6 +91,14 @@ struct IOOptions {
   // Type of data being read/written
   IOType type;
 
+  // EXPERIMENTAL
+  // An option map that's opaque to RocksDB. It can be used to implement a
+  // custom contract between a FileSystem user and the provider. This is only
+  // useful in cases where a RocksDB user directly uses the FileSystem or file
+  // object for their own purposes, and wants to pass extra options to APIs
+  // such as NewRandomAccessFile and NewWritableFile.
+  std::unordered_map<std::string, std::string> property_bag;
+
   IOOptions() : timeout(0), prio(IOPriority::kIOLow), type(IOType::kUnknown) {}
 };