diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -152,6 +152,7 @@
   llvm::SmallVector<llvm::StringRef, 0> undefined;
   llvm::SmallVector<SymbolVersion, 0> dynamicList;
   llvm::SmallVector<uint8_t, 0> buildIdVector;
+  llvm::SmallVector<llvm::StringRef, 0> mllvmOpts;
   llvm::MapVector<std::pair<const InputSectionBase *, const InputSectionBase *>,
                   uint64_t>
       callGraphProfile;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1347,8 +1347,10 @@
   config->passPlugins = args::getStrings(args, OPT_load_pass_plugins);
 
   // Parse -mllvm options.
-  for (auto *arg : args.filtered(OPT_mllvm))
+  for (auto *arg : args.filtered(OPT_mllvm)) {
     parseClangOption(arg->getValue(), arg->getSpelling());
+    config->mllvmOpts.insert(config->mllvmOpts.end(), arg->getValue());
+  }
 
   // --threads= takes a positive integer and provides the default value for
   // --thinlto-jobs=.
diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -79,6 +79,8 @@
   c.Options = initTargetOptionsFromCodeGenFlags();
   c.Options.RelaxELFRelocations = true;
   c.Options.EmitAddrsig = true;
+  for (const auto C : config->mllvmOpts)
+    c.MllvmArgs.emplace_back(C.str());
 
   // Always emit a section per function/datum with LTO.
   c.Options.FunctionSections = true;
diff --git a/lld/test/ELF/lto/cache.ll b/lld/test/ELF/lto/cache.ll
--- a/lld/test/ELF/lto/cache.ll
+++ b/lld/test/ELF/lto/cache.ll
@@ -51,6 +51,23 @@
 ; CHECK: llvmcache-newer
 ; CHECK-NOT: llvmcache-old
 
+; Check that mllvm options participate in the cache key
+; RUN: rm -rf %t.cache
+; RUN: mkdir %t.cache
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o
+; RUN: ls %t.cache | count 3
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default
+; RUN: ls %t.cache | count 5
+; Adding another option resuls in 2 more cache entries
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1
+; RUN: ls %t.cache | count 7
+; Changing order may matter - e.g. if overriding -mllvm options - so we get 2 more entries
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -max-devirt-iterations=1 -mllvm -enable-ml-inliner=default
+; RUN: ls %t.cache | count 9
+; Going back to a pre-cached order doesn't create more entries.
+; RUN: ld.lld --thinlto-cache-dir=%t.cache -o %t3 %t2.o %t.o -mllvm -enable-ml-inliner=default -mllvm -max-devirt-iterations=1
+; RUN: ls %t.cache | count 9
+
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
diff --git a/llvm/include/llvm/LTO/Config.h b/llvm/include/llvm/LTO/Config.h
--- a/llvm/include/llvm/LTO/Config.h
+++ b/llvm/include/llvm/LTO/Config.h
@@ -48,6 +48,7 @@
   TargetOptions Options;
   std::vector<std::string> MAttrs;
   std::vector<std::string> PassPlugins;
+  std::vector<std::string> MllvmArgs;
   /// For adding passes that run right before codegen.
   std::function<void(legacy::PassManager &)> PreCodeGenPassesHook;
   Optional<Reloc::Model> RelocModel = Reloc::PIC_;
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -131,6 +131,8 @@
     AddUnsigned(*Conf.CodeModel);
   else
     AddUnsigned(-1);
+  for (const auto &S : Conf.MllvmArgs)
+    AddString(S);
   AddUnsigned(Conf.CGOptLevel);
   AddUnsigned(Conf.CGFileType);
   AddUnsigned(Conf.OptLevel);