diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index d092e44e7..87afae7ed 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -376,6 +376,7 @@ struct IDLOptions {
   std::string go_namespace;
   bool reexport_ts_modules;
   bool protobuf_ascii_alike;
+  bool prefix_size;
 
   // Possible options for the more general generator below.
   enum Language {
@@ -428,6 +429,7 @@ struct IDLOptions {
       skip_flatbuffers_import(false),
       reexport_ts_modules(true),
       protobuf_ascii_alike(false),
+      prefix_size(false),
       lang(IDLOptions::kJava),
       mini_reflect(IDLOptions::kNone),
       lang_to_generate(0) {}
diff --git a/src/flatc.cpp b/src/flatc.cpp
index abc948c2c..61e434312 100644
--- a/src/flatc.cpp
+++ b/src/flatc.cpp
@@ -113,6 +113,7 @@ std::string FlatCompiler::GetUsageString(const char* program_name) const {
       "  --no-ts-reexport   Don't re-export imported dependencies for TypeScript.\n"
       "  --reflect-types    Add minimal type reflection to code generation.\n"
       "  --reflect-names    Add minimal type/name reflection.\n"
+      "  --prefix-size      Prefix size field to generated buffers.\n"
       "FILEs may be schemas (must end in .fbs), or JSON files (conforming to preceding\n"
       "schema). FILEs after the -- must be binary flatbuffer format files.\n"
       "Output files are named using the base file name of the input,\n"
@@ -249,6 +250,8 @@ int FlatCompiler::Compile(int argc, const char** argv) {
         opts.mini_reflect = IDLOptions::kTypes;
       } else if(arg == "--reflect-names") {
         opts.mini_reflect = IDLOptions::kTypesAndNames;
+      } else if(arg == "--prefix-size") {
+        opts.prefix_size = true;
       } else {
         for (size_t i = 0; i < params_.num_generators; ++i) {
           if (arg == params_.generators[i].generator_opt_long ||
diff --git a/src/idl_parser.cpp b/src/idl_parser.cpp
index b919c3c53..be52de006 100644
--- a/src/idl_parser.cpp
+++ b/src/idl_parser.cpp
@@ -2204,8 +2204,13 @@ CheckedError Parser::DoParse(const char *source,
       }
       uoffset_t toff;
       ECHECK(ParseTable(*root_struct_def_, nullptr, &toff));
-      builder_.Finish(Offset<Table>(toff),
-                file_identifier_.length() ? file_identifier_.c_str() : nullptr);
+      if (opts.prefix_size) {
+        builder_.FinishSizePrefixed(Offset<Table>(toff),
+                  file_identifier_.length() ? file_identifier_.c_str() : nullptr);
+      } else {
+        builder_.Finish(Offset<Table>(toff),
+                  file_identifier_.length() ? file_identifier_.c_str() : nullptr);
+      }
     } else if (IsIdent("enum")) {
       ECHECK(ParseEnum(false, nullptr));
     } else if (IsIdent("union")) {
@@ -2317,7 +2322,11 @@ void Parser::Serialize() {
                          root_struct_def_
                            ? root_struct_def_->serialized_location
                            : 0);
-  builder_.Finish(schema_offset, reflection::SchemaIdentifier());
+  if (opts.prefix_size) {
+    builder_.FinishSizePrefixed(schema_offset, reflection::SchemaIdentifier());
+  } else {
+    builder_.Finish(schema_offset, reflection::SchemaIdentifier());
+  }
 }
 
 Offset<reflection::Object> StructDef::Serialize(FlatBufferBuilder *builder,