diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2544,6 +2544,19 @@
   let Documentation = [VectorCallDocs];
 }
 
+def ZeroCallUsedRegs : InheritableAttr {
+  let Spellings = [GCC<"zero_call_used_regs">];
+  let Subjects = SubjectList<[Function], ErrorDiag>;
+  let Args = [
+    EnumArgument<"ZeroCallUsedRegs", "ZeroCallUsedRegsKind",
+                 ["skip", "used-gpr-arg", "used-gpr", "used-arg", "used",
+                  "all-gpr-arg", "all-gpr", "all-arg", "all"],
+                 ["Skip", "UsedGPRArg", "UsedGPR", "UsedArg", "Used",
+                  "AllGPRArg", "AllGPR", "AllArg", "All"]>
+  ];
+  let Documentation = [ZeroCallUsedRegsDocs];
+}
+
 def Pascal : DeclOrTypeAttr {
   let Spellings = [Clang<"pascal">, Keyword<"__pascal">, Keyword<"_pascal">];
 //  let Subjects = [Function, ObjCMethod];
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -6101,3 +6101,36 @@
   }
   }];
 }
+
+def ZeroCallUsedRegsDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+This attribute, when attached to a funcditon, causes the compiler to zero a
+subset of all call-used registers before the function returns. It's used to
+increase program security by either mitigating `Return-Oriented Programming`_
+(ROP) attacks or preventing information leakage through registers.
+
+The `choice` parameters gives the programmer flexibility to choose the subset
+of the call-used registers to be zeroed:
+
+- ``skip`` doesn't zero any call-used registers.
+- ``used`` only zeros call-used registers used in the function. By ``used``, we
+  mean a register whose contents have been set or referenced in the function.
+- ``used-gpr`` only zeros call-used GPR registers used in the funciton.
+- ``used-arg`` only zeros call-used registers used to pass arguments to the
+  function.
+- ``used-gpr-arg`` only zeros call-used GPR registers used to pass arguments to
+  the function.
+- ``all`` zeros all call-used registers.
+- ``all-gpr`` zeros all call-used GPR registers.
+- ``all-arg`` zeros all call-used registers used to pass arguments to the
+  function.
+- ``all-gpr-arg`` zeros all call-used GPR registers used to pass arguments to
+  the function.
+
+The default for the attribute is contolled by the ``-fzero-call-used-regs``
+flag.
+
+.. _Return-Oriented Programming: https://en.wikipedia.org/wiki/Return-oriented_programming
+  }];
+}
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -451,6 +451,10 @@
 ENUM_CODEGENOPT(SwiftAsyncFramePointer, SwiftAsyncFramePointerKind, 2,
                 SwiftAsyncFramePointerKind::Always)
 
+/// Whether to zero out caller-used registers before returning.
+ENUM_CODEGENOPT(ZeroCallUsedRegs, llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind,
+                5, llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Skip)
+
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
 #undef VALUE_CODEGENOPT
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2856,6 +2856,14 @@
     HelpText<"Enable matrix data type and related builtin functions">,
     MarshallingInfoFlag<LangOpts<"MatrixTypes">>;
 
+def fzero_call_used_regs_EQ
+    : Joined<["-"], "fzero-call-used-regs=">, Group<f_Group>, Flags<[CC1Option]>,
+      HelpText<"Clear call-used registers upon function return.">,
+      Values<"skip,used-gpr-arg,used-gpr,used-arg,used,all-gpr-arg,all-gpr,all-arg,all">,
+      NormalizedValues<["Skip", "UsedGPRArg", "UsedGPR", "UsedArg", "Used",
+                        "AllGPRArg", "AllGPR", "AllArg", "All"]>,
+      NormalizedValuesScope<"llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind">,
+      MarshallingInfoEnum<CodeGenOpts<"ZeroCallUsedRegs">, "Skip">;
 
 def fdebug_types_section: Flag <["-"], "fdebug-types-section">, Group<f_Group>,
   HelpText<"Place debug types in their own section (ELF Only)">;
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1877,6 +1877,37 @@
 
     if (CodeGenOpts.SpeculativeLoadHardening)
       FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
+
+    // Add zero-call-used-regs attribute.
+    switch (CodeGenOpts.getZeroCallUsedRegs()) {
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Skip:
+      FuncAttrs.removeAttribute("zero-call-used-regs");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::UsedGPRArg:
+      FuncAttrs.addAttribute("zero-call-used-regs", "used-gpr-arg");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::UsedGPR:
+      FuncAttrs.addAttribute("zero-call-used-regs", "used-gpr");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::UsedArg:
+      FuncAttrs.addAttribute("zero-call-used-regs", "used-arg");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Used:
+      FuncAttrs.addAttribute("zero-call-used-regs", "used");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::AllGPRArg:
+      FuncAttrs.addAttribute("zero-call-used-regs", "all-gpr-arg");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::AllGPR:
+      FuncAttrs.addAttribute("zero-call-used-regs", "all-gpr");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::AllArg:
+      FuncAttrs.addAttribute("zero-call-used-regs", "all-arg");
+      break;
+    case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::All:
+      FuncAttrs.addAttribute("zero-call-used-regs", "all");
+      break;
+    }
   }
 
   if (getLangOpts().assumeFunctionsAreConvergent()) {
@@ -2166,6 +2197,15 @@
       FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
     if (TargetDecl->hasAttr<NoSplitStackAttr>())
       FuncAttrs.removeAttribute("split-stack");
+    if (TargetDecl->hasAttr<ZeroCallUsedRegsAttr>()) {
+      // A function "__attribute__((...))" overrides the command-line flag.
+      auto Kind =
+          TargetDecl->getAttr<ZeroCallUsedRegsAttr>()->getZeroCallUsedRegs();
+      FuncAttrs.removeAttribute("zero-call-used-regs");
+      FuncAttrs.addAttribute(
+          "zero-call-used-regs",
+          ZeroCallUsedRegsAttr::ConvertZeroCallUsedRegsKindToStr(Kind));
+    }
 
     // Add NonLazyBind attribute to function declarations when -fno-plt
     // is used.
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5728,6 +5728,7 @@
   Args.AddLastArg(CmdArgs, options::OPT_fdigraphs, options::OPT_fno_digraphs);
   Args.AddLastArg(CmdArgs, options::OPT_femulated_tls,
                   options::OPT_fno_emulated_tls);
+  Args.AddLastArg(CmdArgs, options::OPT_fzero_call_used_regs_EQ);
 
   // AltiVec-like language extensions aren't relevant for assembling.
   if (!isa<PreprocessJobAction>(JA) || Output.getType() != types::TY_PP_Asm)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -7574,6 +7574,24 @@
   D->addAttr(::new (S.Context) OpenCLAccessAttr(S.Context, AL));
 }
 
+static void handleZeroCallUsedRegsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  // Check that the argument is a string literal.
+  StringRef KindStr;
+  SourceLocation LiteralLoc;
+  if (!S.checkStringLiteralArgumentAttr(AL, 0, KindStr, &LiteralLoc))
+    return;
+
+  ZeroCallUsedRegsAttr::ZeroCallUsedRegsKind kind;
+  if (!ZeroCallUsedRegsAttr::ConvertStrToZeroCallUsedRegsKind(KindStr, kind)) {
+    S.Diag(LiteralLoc, diag::warn_attribute_type_not_supported)
+        << AL << KindStr;
+    return;
+  }
+
+  D->dropAttr<ZeroCallUsedRegsAttr>();
+  D->addAttr(ZeroCallUsedRegsAttr::Create(S.Context, kind, AL));
+}
+
 static void handleSYCLKernelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   // The 'sycl_kernel' attribute applies only to function templates.
   const auto *FD = cast<FunctionDecl>(D);
@@ -8309,6 +8327,9 @@
   case ParsedAttr::AT_InternalLinkage:
     handleInternalLinkageAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_ZeroCallUsedRegs:
+    handleZeroCallUsedRegsAttr(S, D, AL);
+    break;
 
   // Microsoft attributes:
   case ParsedAttr::AT_LayoutVersion:
diff --git a/clang/test/CodeGen/zero-call-used-regs.c b/clang/test/CodeGen/zero-call-used-regs.c
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/zero-call-used-regs.c
@@ -0,0 +1,249 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=skip -o - | FileCheck %s --check-prefix CHECK-SKIP
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=used-gpr-arg -o - | FileCheck %s --check-prefix CHECK-USED-GPR-ARG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=used-gpr -o - | FileCheck %s --check-prefix CHECK-USED-GPR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=used-arg -o - | FileCheck %s --check-prefix CHECK-USED-ARG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=used -o - | FileCheck %s --check-prefix CHECK-USED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=all-gpr-arg -o - | FileCheck %s --check-prefix CHECK-ALL-GPR-ARG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=all-gpr -o - | FileCheck %s --check-prefix CHECK-ALL-GPR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=all-arg -o - | FileCheck %s --check-prefix CHECK-ALL-ARG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -emit-llvm -fzero-call-used-regs=all -o - | FileCheck %s --check-prefix CHECK-ALL
+
+// -fzero-call-used-regs=skip:
+//
+// CHECK-SKIP:               define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-SKIP:               define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-SKIP-NOT:           attributes #[[ATTR_NUM]] = {{.*}} "zero-call-used-regs"=
+// CHECK-SKIP:               attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-SKIP:               attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=used-gpr-arg:
+//
+// CHECK-USED-GPR-ARG:       define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-USED-GPR-ARG:       define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-USED-GPR-ARG:       attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=used-gpr:
+//
+// CHECK-USED-GPR:           define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR]]
+// CHECK-USED-GPR:           define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-USED-GPR:           define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-USED-GPR:           attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=used-arg:
+//
+// CHECK-USED-ARG:           define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG]]
+// CHECK-USED-ARG:           define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-USED-ARG:           define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-USED-ARG:           attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=used:
+//
+// CHECK-USED:               define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-USED:               define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-USED:               define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-USED:               define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-USED:               define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-USED:               define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED]]
+// CHECK-USED:               define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-USED:               define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-USED:               define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-USED:               define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-USED:               attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-USED:               attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-USED:               attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-USED:               attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-USED:               attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-USED:               attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-USED:               attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-USED:               attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-USED:               attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=all-gpr-arg:
+//
+// CHECK-ALL-GPR-ARG:        define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-ALL-GPR-ARG:        define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-ALL-GPR-ARG:        attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=all-gpr:
+//
+// CHECK-ALL-GPR:            define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR]]
+// CHECK-ALL-GPR:            define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-ALL-GPR:            define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-ALL-GPR:            attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=all-arg:
+//
+// CHECK-ALL-ARG:            define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-ALL-ARG:            define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG]]
+// CHECK-ALL-ARG:            define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+//
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-ALL-ARG:            attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+
+// -fzero-call-used-regs=all:
+//
+// CHECK-ALL:                define {{.*}} @no_attribute({{.*}} #[[ATTR_NUM_ALL:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @skip_test({{.*}} #[[ATTR_NUM_SKIP:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @used_gpr_arg_test({{.*}} #[[ATTR_NUM_USED_GPR_ARG:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @used_gpr_test({{.*}} #[[ATTR_NUM_USED_GPR:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @used_arg_test({{.*}} #[[ATTR_NUM_USED_ARG:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @used_test({{.*}} #[[ATTR_NUM_USED:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @all_gpr_arg_test({{.*}} #[[ATTR_NUM_ALL_GPR_ARG:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @all_gpr_test({{.*}} #[[ATTR_NUM_ALL_GPR:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @all_arg_test({{.*}} #[[ATTR_NUM_ALL_ARG:[0-9]*]]
+// CHECK-ALL:                define {{.*}} @all_test({{.*}} #[[ATTR_NUM_ALL]]
+//
+// CHECK-ALL:                attributes #[[ATTR_NUM_ALL]] = {{.*}} "zero-call-used-regs"="all"
+// CHECK-ALL:                attributes #[[ATTR_NUM_SKIP]] = {{.*}} "zero-call-used-regs"="skip"
+// CHECK-ALL:                attributes #[[ATTR_NUM_USED_GPR_ARG]] = {{.*}} "zero-call-used-regs"="used-gpr-arg"
+// CHECK-ALL:                attributes #[[ATTR_NUM_USED_GPR]] = {{.*}} "zero-call-used-regs"="used-gpr"
+// CHECK-ALL:                attributes #[[ATTR_NUM_USED_ARG]] = {{.*}} "zero-call-used-regs"="used-arg"
+// CHECK-ALL:                attributes #[[ATTR_NUM_USED]] = {{.*}} "zero-call-used-regs"="used"
+// CHECK-ALL:                attributes #[[ATTR_NUM_ALL_GPR_ARG]] = {{.*}} "zero-call-used-regs"="all-gpr-arg"
+// CHECK-ALL:                attributes #[[ATTR_NUM_ALL_GPR]] = {{.*}} "zero-call-used-regs"="all-gpr"
+// CHECK-ALL:                attributes #[[ATTR_NUM_ALL_ARG]] = {{.*}} "zero-call-used-regs"="all-arg"
+
+#define __zero_call_used_regs(...) __attribute__((zero_call_used_regs(__VA_ARGS__)))
+
+void no_attribute() {
+}
+
+void __zero_call_used_regs("skip") skip_test() {
+}
+
+void __zero_call_used_regs("used-gpr-arg") used_gpr_arg_test() {
+}
+
+void __zero_call_used_regs("used-gpr") used_gpr_test() {
+}
+
+void __zero_call_used_regs("used-arg") used_arg_test() {
+}
+
+void __zero_call_used_regs("used") used_test() {
+}
+
+void __zero_call_used_regs("all-gpr-arg") all_gpr_arg_test() {
+}
+
+void __zero_call_used_regs("all-gpr") all_gpr_test() {
+}
+
+void __zero_call_used_regs("all-arg") all_arg_test() {
+}
+
+void __zero_call_used_regs("all") all_test() {
+}
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -188,4 +188,5 @@
 // CHECK-NEXT: WorkGroupSizeHint (SubjectMatchRule_function)
 // CHECK-NEXT: XRayInstrument (SubjectMatchRule_function, SubjectMatchRule_objc_method)
 // CHECK-NEXT: XRayLogArgs (SubjectMatchRule_function, SubjectMatchRule_objc_method)
+// CHECK-NEXT: ZeroCallUsedRegs (SubjectMatchRule_function)
 // CHECK-NEXT: End of supported attributes.
diff --git a/clang/test/Sema/zero_call_used_regs.c b/clang/test/Sema/zero_call_used_regs.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/zero_call_used_regs.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 %s -verify -fno-builtin
+
+#define _zero_call_used_regs(...) __attribute__((zero_call_used_regs(__VA_ARGS__)))
+
+void failure() _zero_call_used_regs();                   // expected-error {{takes one argument}}
+void failure() _zero_call_used_regs("used", "used-gpr"); // expected-error {{takes one argument}}
+void failure() _zero_call_used_regs(0);                  // expected-error {{requires a string}}
+void failure() _zero_call_used_regs("hello");            // expected-warning {{argument not supported: hello}}
+
+void success() _zero_call_used_regs("skip");
+void success() _zero_call_used_regs("used-gpr-arg");
+void success() _zero_call_used_regs("used-gpr");
+void success() _zero_call_used_regs("used-arg");
+void success() _zero_call_used_regs("used");
+void success() _zero_call_used_regs("all-gpr-arg");
+void success() _zero_call_used_regs("all-gpr");
+void success() _zero_call_used_regs("all-arg");
+void success() _zero_call_used_regs("all");
diff --git a/llvm/include/llvm/Support/CodeGen.h b/llvm/include/llvm/Support/CodeGen.h
--- a/llvm/include/llvm/Support/CodeGen.h
+++ b/llvm/include/llvm/Support/CodeGen.h
@@ -69,6 +69,35 @@
   // Specify what functions should keep the frame pointer.
   enum class FramePointerKind { None, NonLeaf, All };
 
+  // Specify what type of zeroing callee-used registers.
+  namespace ZeroCallUsedRegs {
+  const unsigned ONLY_USED = 1UL << 1;
+  const unsigned ONLY_GPR = 1UL << 2;
+  const unsigned ONLY_ARG = 1UL << 3;
+  const unsigned ENABLED = 1UL << 4;
+
+  enum class ZeroCallUsedRegsKind : unsigned int {
+    // Don't zero any call-used regs.
+    Skip = 1UL << 0,
+    // Only zeros call-used GPRs used in the fn and pass args.
+    UsedGPRArg = ENABLED | ONLY_USED | ONLY_GPR | ONLY_ARG,
+    // Only zeros call-used GPRs used in the fn.
+    UsedGPR = ENABLED | ONLY_USED | ONLY_GPR,
+    // Only zeros call-used regs used in the fn and pass args.
+    UsedArg = ENABLED | ONLY_USED | ONLY_ARG,
+    // Only zeros call-used regs used in the fn.
+    Used = ENABLED | ONLY_USED,
+    // Zeros all call-used GPRs that pass args.
+    AllGPRArg = ENABLED | ONLY_GPR | ONLY_ARG,
+    // Zeros all call-used GPRs.
+    AllGPR = ENABLED | ONLY_GPR,
+    // Zeros all call-used regs that pass args.
+    AllArg = ENABLED | ONLY_ARG,
+    // Zeros all call-used regs.
+    All = ENABLED,
+  };
+  } // namespace ZeroCallUsedRegs
+
 }  // end llvm namespace
 
 #endif
diff --git a/llvm/lib/Target/X86/X86FrameLowering.h b/llvm/lib/Target/X86/X86FrameLowering.h
--- a/llvm/lib/Target/X86/X86FrameLowering.h
+++ b/llvm/lib/Target/X86/X86FrameLowering.h
@@ -227,6 +227,11 @@
                                        const DebugLoc &DL, uint64_t Offset,
                                        uint64_t Align) const;
 
+  /// Emit target zero call-used regs.
+  void emitZeroCallUsedRegs(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator &MBBI,
+                            const DebugLoc &DL) const;
+
   void adjustFrameForMsvcCxxEh(MachineFunction &MF) const;
 
   /// Aligns the stack pointer by ANDing it with -MaxAlign.
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -484,6 +484,178 @@
   }
 }
 
+void X86FrameLowering::emitZeroCallUsedRegs(MachineBasicBlock &MBB,
+                                            MachineBasicBlock::iterator &MBBI,
+                                            const DebugLoc &DL) const {
+  MachineFunction &MF = *MBB.getParent();
+  const Function &F = MF.getFunction();
+
+  if (!F.hasFnAttribute("zero-call-used-regs") ||
+      // No need to zero call regs in main().
+      (F.hasExternalLinkage() && F.getName() == "main"))
+    return;
+
+  using namespace ZeroCallUsedRegs;
+
+  ZeroCallUsedRegsKind ZeroRegsKind =
+      StringSwitch<ZeroCallUsedRegsKind>(
+          F.getFnAttribute("zero-call-used-regs").getValueAsString())
+          .Case("skip", ZeroCallUsedRegsKind::Skip)
+          .Case("used-gpr-arg", ZeroCallUsedRegsKind::UsedGPRArg)
+          .Case("used-gpr", ZeroCallUsedRegsKind::UsedGPR)
+          .Case("used-arg", ZeroCallUsedRegsKind::UsedArg)
+          .Case("used", ZeroCallUsedRegsKind::Used)
+          .Case("all-gpr-arg", ZeroCallUsedRegsKind::AllGPRArg)
+          .Case("all-gpr", ZeroCallUsedRegsKind::AllGPR)
+          .Case("all-arg", ZeroCallUsedRegsKind::AllArg)
+          .Case("all", ZeroCallUsedRegsKind::All);
+
+  if (ZeroRegsKind == ZeroCallUsedRegsKind::Skip)
+    return;
+
+  const bool Is64Bit = STI.is64Bit();
+  const bool OnlyGPR = static_cast<unsigned>(ZeroRegsKind) & ONLY_GPR;
+  const bool OnlyUsed = static_cast<unsigned>(ZeroRegsKind) & ONLY_USED;
+  const bool OnlyArg = static_cast<unsigned>(ZeroRegsKind) & ONLY_ARG;
+
+  const X86RegisterInfo &MRI = *STI.getRegisterInfo();
+  BitVector ArgumentRegs = MRI.getArgumentRegs(MF);
+
+  // Add call-used registers we could zero out.
+  auto AddRegs = [&](BitVector &Regs, const TargetRegisterClass &TRC) {
+    llvm::for_each(TRI->getAllocatableSet(MF, &TRC).set_bits(),
+                   [&](MCRegister Reg) { Regs.set(Reg); });
+  };
+
+  BitVector CallUsedRegs(MRI.getNumRegs());
+
+  // GPRs.
+  AddRegs(CallUsedRegs, X86::GR32RegClass);
+
+  if (Is64Bit)
+    AddRegs(CallUsedRegs, X86::GR64RegClass);
+
+  // *MM registers.
+  if (STI.hasSSE1())
+    AddRegs(CallUsedRegs, X86::VR128RegClass);
+  if (STI.hasAVX())
+    AddRegs(CallUsedRegs, X86::VR256RegClass);
+  if (STI.hasAVX512())
+    AddRegs(CallUsedRegs, X86::VR512RegClass);
+
+  // Floating-point stack registers.
+  AddRegs(CallUsedRegs, X86::RFP80RegClass);
+
+  // TODO: MMX registers?
+
+  BitVector UsedRegs(MRI.getNumRegs());
+  llvm::for_each(MF, [&](const MachineBasicBlock &MBB) {
+    llvm::for_each(MBB, [&](const MachineInstr &MI) {
+      llvm::for_each(MI.operands(), [&](MachineOperand MO) {
+        if (MO.isReg() && (MO.isDef() || MO.isUse())) {
+          MCRegister Reg = MO.getReg();
+
+          if (X86::GR32RegClass.contains(Reg)) {
+            if (auto SReg = TRI->getMatchingSuperReg(Reg, X86::sub_32bit,
+                                                     &X86::GR32RegClass))
+              Reg = SReg;
+          }
+          UsedRegs.set(Reg);
+        }
+      });
+    });
+  });
+
+  BitVector RegsToZero(MRI.getNumRegs());
+  for (auto Reg : CallUsedRegs.set_bits()) {
+    // Want only GPR register.
+    if (OnlyGPR && !X86::GR64RegClass.contains(Reg) &&
+        !X86::GR32RegClass.contains(Reg))
+      continue;
+
+    // Want only used registers.
+    if (OnlyUsed && !UsedRegs[Reg])
+      continue;
+
+    // Want only registers used for arguments.
+    if (OnlyArg && !ArgumentRegs[Reg])
+      continue;
+
+    RegsToZero.set(Reg);
+  }
+
+  // Remove registers are live when leaving the function.
+  llvm::for_each(MBB.terminators(), [&](MachineInstr &MI) {
+    if (!MI.isReturn())
+      return;
+
+    for (auto MO : MI.operands())
+      if (MO.isReg())
+        RegsToZero.reset(MO.getReg());
+  });
+
+  // Don't clear registers that will just be reset before exiting.
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  for (auto CSI : MFI.getCalleeSavedInfo())
+    RegsToZero.reset(CSI.getReg());
+
+  // Position to place register zeroing instructions.
+  MachineBasicBlock::iterator InsertPt = MBB.getFirstTerminator();
+
+  // Zero out FP stack if referenced. Do this outside of the loop below so that
+  // it's done only once.
+  for (MCRegister Reg : RegsToZero.set_bits()) {
+    if (!X86::RFP80RegClass.contains(Reg))
+      continue;
+
+    unsigned NumStackSlots = Is64Bit ? 8 : 7;
+    for (unsigned I = 0; I < NumStackSlots; ++I)
+      BuildMI(MBB, InsertPt, DebugLoc(), TII.get(X86::LD_F0));
+
+    for (unsigned I = 0; I < NumStackSlots; ++I)
+      BuildMI(MBB, InsertPt, DebugLoc(), TII.get(X86::ST_FPrr))
+          .addReg(X86::ST0);
+
+    break;
+  }
+
+  for (auto Reg : RegsToZero.set_bits()) {
+    if (X86::RFP80RegClass.contains(Reg))
+      // Handled above.
+      continue;
+
+    unsigned XorOp;
+    if (X86::VR128RegClass.contains(Reg)) { // SSE
+      XorOp = X86::PXORrr;
+    } else if (X86::VR256RegClass.contains(Reg)) { // AVX
+      XorOp = X86::VPXORrr;
+    } else if (X86::VR512RegClass.contains(Reg)) { // AVX2
+      XorOp = X86::VPXORYrr;
+    } else {
+      if (!X86::GR32RegClass.contains(Reg)) {
+        if (!UsedRegs[Reg])
+          // Even in "all-*" mode, we only emit 64-bit registers if they're
+          // used.
+          continue;
+
+        XorOp = X86::XOR64rr;
+      } else {
+        MCRegister SuperReg =
+            TRI->getMatchingSuperReg(Reg, X86::sub_32bit, &X86::GR64RegClass);
+
+        if (UsedRegs[SuperReg])
+          continue;
+
+        XorOp = X86::XOR32rr;
+      }
+    }
+
+    BuildMI(MBB, InsertPt, DebugLoc(), TII.get(XorOp), Reg)
+        .addReg(Reg, RegState::Undef)
+        .addReg(Reg, RegState::Undef);
+  }
+}
+
 void X86FrameLowering::emitStackProbe(MachineFunction &MF,
                                       MachineBasicBlock &MBB,
                                       MachineBasicBlock::iterator MBBI,
@@ -2201,6 +2373,9 @@
     }
   }
 
+  // Emit code for "zero-call-used-regs" attributes.
+  emitZeroCallUsedRegs(MBB, AfterPop, DL);
+
   // Emit DWARF info specifying the restores of the callee-saved registers.
   // For epilogue with return inside or being other block without successor,
   // no need to generate .cfi_restore for callee-saved registers.
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.h b/llvm/lib/Target/X86/X86RegisterInfo.h
--- a/llvm/lib/Target/X86/X86RegisterInfo.h
+++ b/llvm/lib/Target/X86/X86RegisterInfo.h
@@ -115,6 +115,12 @@
   /// register scavenger to determine what registers are free.
   BitVector getReservedRegs(const MachineFunction &MF) const override;
 
+  /// getArgumentRegs - Returns a bitvector indexed by physical register number
+  /// indication if a register is used as part of the calling convention or not.
+  /// Only super registers are returned; subregisters--e.g. AL, BH, CX--are
+  /// omitted.
+  BitVector getArgumentRegs(const MachineFunction &MF) const;
+
   void adjustStackMapLiveOutMask(uint32_t *Mask) const override;
 
   bool hasBasePointer(const MachineFunction &MF) const;
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.cpp b/llvm/lib/Target/X86/X86RegisterInfo.cpp
--- a/llvm/lib/Target/X86/X86RegisterInfo.cpp
+++ b/llvm/lib/Target/X86/X86RegisterInfo.cpp
@@ -618,6 +618,68 @@
   return Reserved;
 }
 
+BitVector X86RegisterInfo::getArgumentRegs(const MachineFunction &MF) const {
+  const X86Subtarget &Subtarget = MF.getSubtarget<X86Subtarget>();
+  bool HasSSE = Subtarget.hasSSE1();
+  bool HasAVX = Subtarget.hasAVX();
+  bool HasAVX512 = Subtarget.hasAVX512();
+
+  BitVector ArgumentRegs(getNumRegs());
+
+  auto SetArgRegs = [&ArgumentRegs](ArrayRef<MCRegister> Regs) {
+    for (auto Reg : Regs)
+      ArgumentRegs.set(Reg);
+  };
+
+  SetArgRegs({X86::EAX, X86::ECX, X86::EDX, X86::EDI, X86::ESI});
+
+  if (!Is64Bit) {
+    if (HasSSE)
+      SetArgRegs({X86::XMM0, X86::XMM1, X86::XMM2});
+
+    if (HasAVX)
+      SetArgRegs({X86::YMM0, X86::YMM1, X86::YMM2});
+
+    if (HasAVX512)
+      SetArgRegs({X86::ZMM0, X86::ZMM1, X86::ZMM2});
+
+    return ArgumentRegs;
+  }
+
+  const Function &F = MF.getFunction();
+  CallingConv::ID CC = F.getCallingConv();
+
+  if (CC == CallingConv::X86_64_SysV)
+    SetArgRegs({X86::RAX});
+
+  if (HasSSE)
+    SetArgRegs({X86::XMM0, X86::XMM1, X86::XMM2, X86::XMM3});
+
+  if (HasAVX)
+    SetArgRegs({X86::YMM0, X86::YMM1, X86::YMM2, X86::YMM3});
+
+  if (HasAVX512)
+    SetArgRegs({X86::ZMM0, X86::ZMM1, X86::ZMM2, X86::ZMM3});
+
+  if (IsWin64 || CC == CallingConv::Win64) {
+    SetArgRegs({X86::RCX, X86::RDX, X86::R8, X86::R9});
+  } else {
+    SetArgRegs({X86::RDI, X86::RSI, X86::RDX, X86::RCX, X86::R8, X86::R9});
+    SetArgRegs({X86::R8D, X86::R9D});
+
+    if (HasSSE)
+      SetArgRegs({X86::XMM5, X86::XMM6, X86::XMM7});
+
+    if (HasAVX)
+      SetArgRegs({X86::YMM5, X86::YMM6, X86::YMM7});
+
+    if (HasAVX512)
+      SetArgRegs({X86::ZMM5, X86::ZMM6, X86::ZMM7});
+  }
+
+  return ArgumentRegs;
+}
+
 void X86RegisterInfo::adjustStackMapLiveOutMask(uint32_t *Mask) const {
   // Check if the EFLAGS register is marked as live-out. This shouldn't happen,
   // because the calling convention defines the EFLAGS register as NOT
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-all-arg.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-all-arg.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-all-arg.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorps %xmm0, %xmm0
+; CHECK-NEXT:    xorps %xmm1, %xmm1
+; CHECK-NEXT:    xorps %xmm2, %xmm2
+; CHECK-NEXT:    xorps %xmm3, %xmm3
+; CHECK-NEXT:    xorps %xmm5, %xmm5
+; CHECK-NEXT:    xorps %xmm6, %xmm6
+; CHECK-NEXT:    xorps %xmm7, %xmm7
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-arg" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-arg" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr-arg.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr-arg.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr-arg.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-gpr-arg" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-gpr-arg" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %ebp, %ebp
+; CHECK-NEXT:    xorl %ebx, %ebx
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    xorl %r10d, %r10d
+; CHECK-NEXT:    xorl %r11d, %r11d
+; CHECK-NEXT:    xorl %r12d, %r12d
+; CHECK-NEXT:    xorl %r13d, %r13d
+; CHECK-NEXT:    xorl %r14d, %r14d
+; CHECK-NEXT:    xorl %r15d, %r15d
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-gpr" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all-gpr" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-all.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-all.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-all.ll
@@ -0,0 +1,73 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    xorl %ebp, %ebp
+; CHECK-NEXT:    xorl %ebx, %ebx
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorps %xmm0, %xmm0
+; CHECK-NEXT:    xorps %xmm1, %xmm1
+; CHECK-NEXT:    xorps %xmm2, %xmm2
+; CHECK-NEXT:    xorps %xmm3, %xmm3
+; CHECK-NEXT:    xorps %xmm4, %xmm4
+; CHECK-NEXT:    xorps %xmm5, %xmm5
+; CHECK-NEXT:    xorps %xmm6, %xmm6
+; CHECK-NEXT:    xorps %xmm7, %xmm7
+; CHECK-NEXT:    xorps %xmm8, %xmm8
+; CHECK-NEXT:    xorps %xmm9, %xmm9
+; CHECK-NEXT:    xorps %xmm10, %xmm10
+; CHECK-NEXT:    xorps %xmm11, %xmm11
+; CHECK-NEXT:    xorps %xmm12, %xmm12
+; CHECK-NEXT:    xorps %xmm13, %xmm13
+; CHECK-NEXT:    xorps %xmm14, %xmm14
+; CHECK-NEXT:    xorps %xmm15, %xmm15
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    xorl %r10d, %r10d
+; CHECK-NEXT:    xorl %r11d, %r11d
+; CHECK-NEXT:    xorl %r12d, %r12d
+; CHECK-NEXT:    xorl %r13d, %r13d
+; CHECK-NEXT:    xorl %r14d, %r14d
+; CHECK-NEXT:    xorl %r15d, %r15d
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="all" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-fmod.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-fmod.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-fmod.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define dso_local float @foo() local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    pushq %rax
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    xorps %xmm0, %xmm0
+; CHECK-NEXT:    xorps %xmm1, %xmm1
+; CHECK-NEXT:    callq fmod
+; CHECK-NEXT:    cvtsd2ss %xmm0, %xmm0
+; CHECK-NEXT:    popq %rax
+; CHECK-NEXT:    .cfi_def_cfa_offset 8
+; CHECK-NEXT:    xorq %rax, %rax
+; CHECK-NEXT:    xorps %xmm1, %xmm1
+; CHECK-NEXT:    retq
+entry:
+  %call = call nnan ninf double @fmod(double 0.000000e+00, double 0.000000e+00) #2
+  %conv = fptrunc double %call to float
+  ret float %conv
+}
+
+declare dso_local double @fmod(double, double) local_unnamed_addr #1
+
+attributes #0 = { mustprogress nofree nounwind uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used" }
+attributes #1 = { mustprogress nofree nounwind willreturn "frame-pointer"="none" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used" }
+attributes #2 = { nounwind }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-skip.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-skip.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-skip.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="skip" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="skip" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-smoke-tests.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-smoke-tests.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-smoke-tests.ll
@@ -0,0 +1,92 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define dso_local void @test_skip_1() local_unnamed_addr #0 {
+; CHECK-LABEL: test_skip_1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    retq
+entry:
+  ret void
+}
+
+define dso_local void @test_skip_2() local_unnamed_addr #0 "zero-call-used-regs"="skip" {
+; CHECK-LABEL: test_skip_2:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    retq
+entry:
+  ret void
+}
+
+define dso_local void @test_used_1() local_unnamed_addr #0 "zero-call-used-regs"="used" {
+; CHECK-LABEL: test_used_1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    retq
+entry:
+  ret void
+}
+
+define dso_local void @test_used_gpr_1() local_unnamed_addr #0 "zero-call-used-regs"="used-gpr" {
+; CHECK-LABEL: test_used_gpr_1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    retq
+entry:
+  ret void
+}
+
+define dso_local i32 @test_used_gpr_2(i32 returned %x) local_unnamed_addr #0 "zero-call-used-regs"="used-gpr" {
+; CHECK-LABEL: test_used_gpr_2:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local void @test_all_gpr_1() local_unnamed_addr #0 "zero-call-used-regs"="all-gpr" {
+; CHECK-LABEL: test_all_gpr_1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    xorl %ebp, %ebp
+; CHECK-NEXT:    xorl %ebx, %ebx
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    xorl %r10d, %r10d
+; CHECK-NEXT:    xorl %r11d, %r11d
+; CHECK-NEXT:    xorl %r12d, %r12d
+; CHECK-NEXT:    xorl %r13d, %r13d
+; CHECK-NEXT:    xorl %r14d, %r14d
+; CHECK-NEXT:    xorl %r15d, %r15d
+; CHECK-NEXT:    retq
+entry:
+  ret void
+}
+
+define dso_local i32 @test_all_gpr_2(i32 returned %x) local_unnamed_addr #0 "zero-call-used-regs"="all-gpr" {
+; CHECK-LABEL: test_all_gpr_2:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %ebp, %ebp
+; CHECK-NEXT:    xorl %ebx, %ebx
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    xorl %esi, %esi
+; CHECK-NEXT:    xorl %r8d, %r8d
+; CHECK-NEXT:    xorl %r9d, %r9d
+; CHECK-NEXT:    xorl %r10d, %r10d
+; CHECK-NEXT:    xorl %r11d, %r11d
+; CHECK-NEXT:    xorl %r12d, %r12d
+; CHECK-NEXT:    xorl %r13d, %r13d
+; CHECK-NEXT:    xorl %r14d, %r14d
+; CHECK-NEXT:    xorl %r15d, %r15d
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-used-arg.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-used-arg.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-used-arg.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-arg" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-arg" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr-arg.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr-arg.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr-arg.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-gpr-arg" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-gpr-arg" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-gpr" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used-gpr" }
diff --git a/llvm/test/CodeGen/X86/zero-call-used-regs-used.ll b/llvm/test/CodeGen/X86/zero-call-used-regs-used.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/zero-call-used-regs-used.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+@result = dso_local global i32 0, align 4
+
+define dso_local i32 @foo(i32 returned %x) local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    xorl %edi, %edi
+; CHECK-NEXT:    retq
+entry:
+  ret i32 %x
+}
+
+define dso_local i32 @main() local_unnamed_addr #1 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl $2, result(%rip)
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    retq
+entry:
+  store volatile i32 2, i32* @result, align 4
+  ret i32 0
+}
+
+attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used" }
+attributes #1 = { nofree norecurse nounwind uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "zero-call-used-regs"="used" }