diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -162,6 +162,8 @@
 
   // Used for /opt:lldlto=N
   unsigned ltoo = 2;
+  // Used for /opt:lldltocgo=N
+  std::optional<unsigned> ltoCgo;
 
   // Used for /opt:lldltojobs=N
   std::string thinLTOJobs;
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -1768,6 +1768,10 @@
       } else if (s.consume_front("lldlto=")) {
         if (s.getAsInteger(10, config->ltoo) || config->ltoo > 3)
           error("/opt:lldlto: invalid optimization level: " + s);
+      } else if (s.consume_front("lldltocgo=")) {
+        config->ltoCgo.emplace();
+        if (s.getAsInteger(10, *config->ltoCgo) || *config->ltoCgo > 3)
+          error("/opt:lldltocgo: invalid codegen optimization level: " + s);
       } else if (s.consume_front("lldltojobs=")) {
         if (!get_threadpool_strategy(s))
           error("/opt:lldltojobs: invalid job count: " + s);
diff --git a/lld/COFF/LTO.cpp b/lld/COFF/LTO.cpp
--- a/lld/COFF/LTO.cpp
+++ b/lld/COFF/LTO.cpp
@@ -88,7 +88,10 @@
   c.OptLevel = ctx.config.ltoo;
   c.CPU = getCPUStr();
   c.MAttrs = getMAttrs();
-  c.CGOptLevel = args::getCGOptLevel(ctx.config.ltoo);
+  std::optional<CodeGenOpt::Level> optLevelOrNone = CodeGenOpt::getLevel(
+      ctx.config.ltoCgo.value_or(args::getCGOptLevel(ctx.config.ltoo)));
+  assert(optLevelOrNone && "Invalid optimization level!");
+  c.CGOptLevel = *optLevelOrNone;
   c.AlwaysEmitRegularLTOObj = !ctx.config.ltoObjPath.empty();
   c.DebugPassManager = ctx.config.ltoDebugPassManager;
   c.CSIRProfile = std::string(ctx.config.ltoCSProfileFile);
diff --git a/lld/Common/Args.cpp b/lld/Common/Args.cpp
--- a/lld/Common/Args.cpp
+++ b/lld/Common/Args.cpp
@@ -19,11 +19,8 @@
 
 // TODO(sbc): Remove this once CGOptLevel can be set completely based on bitcode
 // function metadata.
-CodeGenOpt::Level lld::args::getCGOptLevel(int optLevelLTO) {
-  if (optLevelLTO == 3)
-    return CodeGenOpt::Aggressive;
-  assert(optLevelLTO < 3);
-  return CodeGenOpt::Default;
+int lld::args::getCGOptLevel(int optLevelLTO) {
+  return std::clamp(optLevelLTO, 2, 3);
 }
 
 static int64_t getInteger(opt::InputArgList &args, unsigned key,
diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -317,6 +317,7 @@
   uint64_t zStackSize;
   unsigned ltoPartitions;
   unsigned ltoo;
+  llvm::CodeGenOpt::Level ltoCgo;
   unsigned optimize;
   StringRef thinLTOJobs;
   unsigned timeTraceGranularity;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1139,6 +1139,14 @@
       args.hasFlag(OPT_lto_whole_program_visibility,
                    OPT_no_lto_whole_program_visibility, false);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
+  if (config->ltoo > 3)
+    error("invalid optimization level for LTO: " + Twine(config->ltoo));
+  unsigned ltoCgo =
+      args::getInteger(args, OPT_lto_CGO, args::getCGOptLevel(config->ltoo));
+  if (auto level = CodeGenOpt::getLevel(ltoCgo))
+    config->ltoCgo = *level;
+  else
+    error("invalid codegen optimization level for LTO: " + Twine(ltoCgo));
   config->ltoObjPath = args.getLastArgValue(OPT_lto_obj_path_eq);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
   config->ltoSampleProfile = args.getLastArgValue(OPT_lto_sample_profile);
@@ -1395,8 +1403,6 @@
     config->thinLTOJobs = arg->getValue();
   config->threadCount = parallel::strategy.compute_thread_count();
 
-  if (config->ltoo > 3)
-    error("invalid optimization level for LTO: " + Twine(config->ltoo));
   if (config->ltoPartitions == 0)
     error("--lto-partitions: number of threads must be > 0");
   if (!get_threadpool_strategy(config->thinLTOJobs))
diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -127,7 +127,7 @@
   c.OptLevel = config->ltoo;
   c.CPU = getCPUStr();
   c.MAttrs = getMAttrs();
-  c.CGOptLevel = args::getCGOptLevel(config->ltoo);
+  c.CGOptLevel = config->ltoCgo;
 
   c.PTO.LoopVectorization = c.OptLevel > 1;
   c.PTO.SLPVectorization = c.OptLevel > 1;
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -558,6 +558,8 @@
   HelpText<"Passes to run during LTO">;
 def lto_O: JJ<"lto-O">, MetaVarName<"<opt-level>">,
   HelpText<"Optimization level for LTO">;
+def lto_CGO: JJ<"lto-CGO">, MetaVarName<"<cgopt-level>">,
+  HelpText<"Codegen optimization level for LTO">;
 def lto_partitions: JJ<"lto-partitions=">,
   HelpText<"Number of LTO codegen partitions">;
 def lto_cs_profile_generate: FF<"lto-cs-profile-generate">,
diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -26,6 +26,10 @@
 
 #include <vector>
 
+namespace llvm::CodeGenOpt {
+enum Level : int;
+} // namespace llvm::CodeGenOpt
+
 namespace lld {
 namespace macho {
 
@@ -165,6 +169,7 @@
   llvm::StringRef thinLTOJobs;
   llvm::StringRef umbrella;
   uint32_t ltoo = 2;
+  llvm::CodeGenOpt::Level ltoCgo;
   llvm::CachePruningPolicy thinLTOCachePolicy;
   llvm::StringRef thinLTOCacheDir;
   llvm::StringRef thinLTOIndexOnlyArg;
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -1421,6 +1421,17 @@
   target = createTargetInfo(args);
   depTracker = std::make_unique<DependencyTracker>(
       args.getLastArgValue(OPT_dependency_info));
+
+  config->ltoo = args::getInteger(args, OPT_lto_O, 2);
+  if (config->ltoo > 3)
+    error("--lto-O: invalid optimization level: " + Twine(config->ltoo));
+  unsigned ltoCgo =
+      args::getInteger(args, OPT_lto_CGO, args::getCGOptLevel(config->ltoo));
+  if (auto level = CodeGenOpt::getLevel(ltoCgo))
+    config->ltoCgo = *level;
+  else
+    error("--lto-CGO: invalid codegen optimization level: " + Twine(ltoCgo));
+
   if (errorCount())
     return false;
 
@@ -1558,9 +1569,6 @@
     config->umbrella = arg->getValue();
   }
   config->ltoObjPath = args.getLastArgValue(OPT_object_path_lto);
-  config->ltoo = args::getInteger(args, OPT_lto_O, 2);
-  if (config->ltoo > 3)
-    error("--lto-O: invalid optimization level: " + Twine(config->ltoo));
   config->thinLTOCacheDir = args.getLastArgValue(OPT_cache_path_lto);
   config->thinLTOCachePolicy = getLTOCachePolicy(args);
   config->thinLTOEmitImportsFiles = args.hasArg(OPT_thinlto_emit_imports_files);
diff --git a/lld/MachO/LTO.cpp b/lld/MachO/LTO.cpp
--- a/lld/MachO/LTO.cpp
+++ b/lld/MachO/LTO.cpp
@@ -70,7 +70,7 @@
   c.TimeTraceEnabled = config->timeTraceEnabled;
   c.TimeTraceGranularity = config->timeTraceGranularity;
   c.OptLevel = config->ltoo;
-  c.CGOptLevel = args::getCGOptLevel(config->ltoo);
+  c.CGOptLevel = config->ltoCgo;
   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
@@ -84,6 +84,10 @@
     HelpText<"Set optimization level for LTO (default: 2)">,
     MetaVarName<"<opt-level>">,
     Group<grp_lld>;
+def lto_CGO: Joined<["--"], "lto-CGO">,
+    HelpText<"Set codegen optimization level for LTO (default: 2)">,
+    MetaVarName<"<cgopt-level>">,
+    Group<grp_lld>;
 def thinlto_cache_policy_eq: Joined<["--"], "thinlto-cache-policy=">,
     HelpText<"Pruning policy for the ThinLTO cache">,
     Group<grp_lld>;
diff --git a/lld/include/lld/Common/Args.h b/lld/include/lld/Common/Args.h
--- a/lld/include/lld/Common/Args.h
+++ b/lld/include/lld/Common/Args.h
@@ -23,7 +23,7 @@
 namespace lld {
 namespace args {
 
-llvm::CodeGenOpt::Level getCGOptLevel(int optLevelLTO);
+int getCGOptLevel(int optLevelLTO);
 
 int64_t getInteger(llvm::opt::InputArgList &args, unsigned key,
                    int64_t Default);
diff --git a/lld/test/COFF/lto-cgo.ll b/lld/test/COFF/lto-cgo.ll
new file mode 100644
--- /dev/null
+++ b/lld/test/COFF/lto-cgo.ll
@@ -0,0 +1,28 @@
+; REQUIRES: x86
+
+; RUN: llvm-as %s -o %t.obj
+; RUN: lld-link -opt:lldlto=0 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: lld-link -opt:lldltocgo=0 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: lld-link -opt:lldlto=3 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: lld-link -opt:lldltocgo=3 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: lld-link -opt:lldlto=0 -opt:lldltocgo=0 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: lld-link -opt:lldlto=3 -opt:lldltocgo=0 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: lld-link -opt:lldlto=0 -opt:lldltocgo=3 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: lld-link -opt:lldlto=3 -opt:lldltocgo=3 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: lld-link -opt:lldlto=0 -opt:lldltocgo=0 -opt:lldltocgo=2 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: not lld-link -opt:lldlto=4 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-O4 %s
+; RUN: not lld-link -opt:lldltocgo=4 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-CGO4 %s
+; RUN: not lld-link -opt:lldlto=4 -opt:lldltocgo=4 %t.obj -dll -noentry -out:%t.dll -mllvm:-debug-pass=Structure 2>&1 | FileCheck --check-prefixes=ERROR-O4,ERROR-CGO4 %s
+
+; NOOPT: Fast Register Allocator
+; OPT: Greedy Register Allocator
+; ERROR-O4: lld-link: error: /opt:lldlto: invalid optimization level: 4
+; ERROR-CGO4: lld-link: error: /opt:lldltocgo: invalid codegen optimization level: 4
+
+target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+define void @_start() {
+entry:
+  ret void
+}
diff --git a/lld/test/ELF/lto/cgo.ll b/lld/test/ELF/lto/cgo.ll
new file mode 100644
--- /dev/null
+++ b/lld/test/ELF/lto/cgo.ll
@@ -0,0 +1,28 @@
+; REQUIRES: x86
+
+; RUN: llvm-as %s -o %t.o
+; RUN: ld.lld --lto-O0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: ld.lld --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: ld.lld --lto-O3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: ld.lld --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: ld.lld --lto-O0 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: ld.lld --lto-O3 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: ld.lld --lto-O0 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: ld.lld --lto-O3 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: ld.lld --lto-O0 --lto-CGO0 --lto-CGO2 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: not ld.lld --lto-O4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-O4 %s
+; RUN: not ld.lld --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-CGO4 %s
+; RUN: not ld.lld --lto-O4 --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefixes=ERROR-O4,ERROR-CGO4 %s
+
+; NOOPT: Fast Register Allocator
+; OPT: Greedy Register Allocator
+; ERROR-O4: ld.lld: error: invalid optimization level for LTO: 4
+; ERROR-CGO4: ld.lld: error: invalid codegen optimization level for LTO: 4
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @_start() {
+entry:
+  ret void
+}
diff --git a/lld/test/MachO/lto-cgo.ll b/lld/test/MachO/lto-cgo.ll
new file mode 100644
--- /dev/null
+++ b/lld/test/MachO/lto-cgo.ll
@@ -0,0 +1,28 @@
+; REQUIRES: x86
+
+; RUN: llvm-as %s -o %t.o
+; RUN: %lld -dylib --lto-O0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: %lld -dylib --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: %lld -dylib --lto-O3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: %lld -dylib --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: %lld -dylib --lto-O0 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: %lld -dylib --lto-O3 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: %lld -dylib --lto-O0 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: %lld -dylib --lto-O3 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: %lld -dylib --lto-O0 --lto-CGO0 --lto-CGO2 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: not %lld -dylib --lto-O4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-O4 %s
+; RUN: not %lld -dylib --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-CGO4 %s
+; RUN: not %lld -dylib --lto-O4 --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefixes=ERROR-O4,ERROR-CGO4 %s
+
+; NOOPT: Fast Register Allocator
+; OPT: Greedy Register Allocator
+; ERROR-O4: ld64.lld: error: --lto-O: invalid optimization level: 4
+; ERROR-CGO4: ld64.lld: error: --lto-CGO: invalid codegen optimization level: 4
+
+target triple = "x86_64-apple-darwin"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @_start() {
+entry:
+  ret void
+}
diff --git a/lld/test/wasm/lto/cgo.ll b/lld/test/wasm/lto/cgo.ll
new file mode 100644
--- /dev/null
+++ b/lld/test/wasm/lto/cgo.ll
@@ -0,0 +1,28 @@
+; REQUIRES: x86
+
+; RUN: llvm-as %s -o %t.o
+; RUN: wasm-ld --lto-O0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: wasm-ld --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: wasm-ld --lto-O3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: wasm-ld --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: wasm-ld --lto-O0 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: wasm-ld --lto-O3 --lto-CGO0 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=NOOPT %s
+; RUN: wasm-ld --lto-O0 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: wasm-ld --lto-O3 --lto-CGO3 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: wasm-ld --lto-O0 --lto-CGO0 --lto-CGO2 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=OPT %s
+; RUN: not wasm-ld --lto-O4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-O4 %s
+; RUN: not wasm-ld --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefix=ERROR-CGO4 %s
+; RUN: not wasm-ld --lto-O4 --lto-CGO4 %t.o -o %t -mllvm -debug-pass=Structure 2>&1 | FileCheck --check-prefixes=ERROR-O4,ERROR-CGO4 %s
+
+; NOOPT-NOT: WebAssembly Optimize Returned
+; OPT: WebAssembly Optimize Returned
+; ERROR-O4: wasm-ld: error: invalid optimization level for LTO: 4
+; ERROR-CGO4: wasm-ld: error: invalid codegen optimization level for LTO: 4
+
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+define void @_start() {
+entry:
+  ret void
+}
diff --git a/lld/wasm/Config.h b/lld/wasm/Config.h
--- a/lld/wasm/Config.h
+++ b/lld/wasm/Config.h
@@ -16,6 +16,10 @@
 #include "llvm/Support/CachePruning.h"
 #include <optional>
 
+namespace llvm::CodeGenOpt {
+enum Level : int;
+} // namespace llvm::CodeGenOpt
+
 namespace lld {
 namespace wasm {
 
@@ -63,6 +67,7 @@
   uint64_t zStackSize;
   unsigned ltoPartitions;
   unsigned ltoo;
+  llvm::CodeGenOpt::Level ltoCgo;
   unsigned optimize;
   llvm::StringRef thinLTOJobs;
   bool ltoDebugPassManager;
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -424,6 +424,14 @@
   config->importTable = args.hasArg(OPT_import_table);
   config->importUndefined = args.hasArg(OPT_import_undefined);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
+  if (config->ltoo > 3)
+    error("invalid optimization level for LTO: " + Twine(config->ltoo));
+  unsigned ltoCgo =
+      args::getInteger(args, OPT_lto_CGO, args::getCGOptLevel(config->ltoo));
+  if (auto level = CodeGenOpt::getLevel(ltoCgo))
+    config->ltoCgo = *level;
+  else
+    error("invalid codegen optimization level for LTO: " + Twine(ltoCgo));
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
   config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
   config->mapFile = args.getLastArgValue(OPT_Map);
@@ -560,8 +568,6 @@
     error("--compress-relocations is incompatible with output debug"
           " information. Please pass --strip-debug or --strip-all");
 
-  if (config->ltoo > 3)
-    error("invalid optimization level for LTO: " + Twine(config->ltoo));
   if (config->ltoPartitions == 0)
     error("--lto-partitions: number of threads must be > 0");
   if (!get_threadpool_strategy(config->thinLTOJobs))
diff --git a/lld/wasm/LTO.cpp b/lld/wasm/LTO.cpp
--- a/lld/wasm/LTO.cpp
+++ b/lld/wasm/LTO.cpp
@@ -51,7 +51,7 @@
   c.DiagHandler = diagnosticHandler;
   c.OptLevel = config->ltoo;
   c.MAttrs = getMAttrs();
-  c.CGOptLevel = args::getCGOptLevel(config->ltoo);
+  c.CGOptLevel = config->ltoCgo;
   c.DebugPassManager = config->ltoDebugPassManager;
 
   if (config->relocatable)
diff --git a/lld/wasm/Options.td b/lld/wasm/Options.td
--- a/lld/wasm/Options.td
+++ b/lld/wasm/Options.td
@@ -256,6 +256,8 @@
 // LTO-related options.
 def lto_O: JJ<"lto-O">, MetaVarName<"<opt-level>">,
   HelpText<"Optimization level for LTO">;
+def lto_CGO: JJ<"lto-CGO">, MetaVarName<"<cgopt-level>">,
+  HelpText<"Codegen optimization level for LTO">;
 def lto_partitions: JJ<"lto-partitions=">,
   HelpText<"Number of LTO codegen partitions">;
 def disable_verify: F<"disable-verify">;