diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -126,6 +126,7 @@
   llvm::StringRef outputFile;
   llvm::StringRef ltoObjPath;
   llvm::StringRef thinLTOJobs;
+  uint32_t ltoo = 2;
   bool deadStripDylibs = false;
   bool demangle = false;
   bool deadStrip = false;
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -1082,6 +1082,9 @@
   config->ltoNewPassManager =
       args.hasFlag(OPT_no_lto_legacy_pass_manager, OPT_lto_legacy_pass_manager,
                    LLVM_ENABLE_NEW_PASS_MANAGER);
+  config->ltoo = args::getInteger(args, OPT_lto_O, 2);
+  if (config->ltoo > 3)
+    error("--lto-O: invalid optimization level: " + Twine(config->ltoo));
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
   config->forceLoadObjC = args.hasArg(OPT_ObjC);
diff --git a/lld/MachO/LTO.cpp b/lld/MachO/LTO.cpp
--- a/lld/MachO/LTO.cpp
+++ b/lld/MachO/LTO.cpp
@@ -13,6 +13,7 @@
 #include "Symbols.h"
 #include "Target.h"
 
+#include "lld/Common/Args.h"
 #include "lld/Common/ErrorHandler.h"
 #include "lld/Common/Strings.h"
 #include "lld/Common/TargetOptionsCommandFlags.h"
@@ -40,6 +41,8 @@
   };
   c.TimeTraceEnabled = config->timeTraceEnabled;
   c.TimeTraceGranularity = config->timeTraceGranularity;
+  c.OptLevel = config->ltoo;
+  c.CGOptLevel = args::getCGOptLevel(config->ltoo);
   if (config->saveTemps)
     checkError(c.addSaveTemps(config->outputFile.str() + ".",
                               /*UseInputModulePath=*/true));
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -64,6 +64,10 @@
     HelpText<"Set level for identical code folding (default: none)">,
     MetaVarName<"[none,safe,all]">,
     Group<grp_lld>;
+def lto_O: Joined<["--"], "lto-O">,
+    HelpText<"Set optimization level for LTO (default: 2)">,
+    MetaVarName<"<opt-level>">,
+    Group<grp_lld>;
 
 // This is a complete Options.td compiled from Apple's ld(1) manpage
 // dated 2018-03-07 and cross checked with ld64 source code in repo