diff --git a/src/engine/config_toolset.bat b/src/engine/config_toolset.bat
index 5280ea6abc..31ba6af5ea 100644
--- a/src/engine/config_toolset.bat
+++ b/src/engine/config_toolset.bat
@@ -156,7 +156,7 @@ REM return to current directory as vsdevcmd_end.bat switches to %USERPROFILE%\So
 pushd %CD%
 if "_%VSINSTALLDIR%_" == "__" call :Call_If_Exists "%B2_TOOLSET_ROOT%Auxiliary\Build\vcvarsall.bat" %B2_BUILD_ARGS%
 popd
-set "B2_CXX="%CXX%" /nologo /MD /TP /Feb2 /wd4996 /wd4675 /O2 /GL /EHsc /Zc:wchar_t /Gw"
+set "B2_CXX="%CXX%" /nologo /MD /TP /Feb2 /wd4996 /wd4675 /Ox /GL /EHsc /Zc:wchar_t /Gw"
 set "B2_CXX_LINK=/link kernel32.lib advapi32.lib user32.lib"
 set "_known_=1"
 goto :Embed_Minafest_Via_Link