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
@@ -231,6 +231,8 @@
ENUM_CODEGENOPT(SanitizeAddressDtor, llvm::AsanDtorKind, 2,
llvm::AsanDtorKind::Global) ///< Set how ASan global
///< destructors are emitted.
+CODEGENOPT(SanitizeMemoryParamRetval, 1, 0) ///
,
NormalizedValues<["None", "Global"]>,
MarshallingInfoEnum, "Global">;
+defm sanitize_memory_param_retval
+ : BoolOption<"f", "sanitize-memory-param-retval",
+ CodeGenOpts<"SanitizeMemoryParamRetval">,
+ DefaultFalse,
+ PosFlag, NegFlag,
+ BothFlags<[], "eager param-retval uninitialized use detection in MemorySanitizer">>,
+ Group;
// Note: This flag was introduced when it was necessary to distinguish between
// ABI for correct codegen. This is no longer needed, but the flag is
// not removed since targeting either ABI will behave the same.
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
@@ -2243,7 +2243,9 @@
getLangOpts().Sanitize.has(SanitizerKind::Return);
// Determine if the return type could be partially undef
- if (CodeGenOpts.EnableNoundefAttrs && HasStrictReturn) {
+ if ((CodeGenOpts.EnableNoundefAttrs ||
+ CodeGenOpts.SanitizeMemoryParamRetval) &&
+ HasStrictReturn) {
if (!RetTy->isVoidType() && RetAI.getKind() != ABIArgInfo::Indirect &&
DetermineNoUndef(RetTy, getTypes(), DL, RetAI))
RetAttrs.addAttribute(llvm::Attribute::NoUndef);
@@ -2378,7 +2380,9 @@
// Decide whether the argument we're handling could be partially undef
bool ArgNoUndef = DetermineNoUndef(ParamType, getTypes(), DL, AI);
- if (CodeGenOpts.EnableNoundefAttrs && ArgNoUndef)
+ if ((CodeGenOpts.EnableNoundefAttrs ||
+ CodeGenOpts.SanitizeMemoryParamRetval) &&
+ ArgNoUndef)
Attrs.addAttribute(llvm::Attribute::NoUndef);
// 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
diff --git a/clang/test/CodeGen/attr-noundef.cpp b/clang/test/CodeGen/attr-noundef.cpp
--- a/clang/test/CodeGen/attr-noundef.cpp
+++ b/clang/test/CodeGen/attr-noundef.cpp
@@ -1,5 +1,7 @@
// RUN: %clang -cc1 -triple x86_64-gnu-linux -x c++ -S -emit-llvm -enable-noundef-analysis %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-INTEL
// RUN: %clang -cc1 -triple aarch64-gnu-linux -x c++ -S -emit-llvm -enable-noundef-analysis %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-AARCH
+// RUN: %clang -cc1 -triple x86_64-gnu-linux -x c++ -S -emit-llvm -fsanitize-memory-param-retval %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-INTEL
+// RUN: %clang -cc1 -triple aarch64-gnu-linux -x c++ -S -emit-llvm -fsanitize-memory-param-retval %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-AARCH
//************ Passing structs by value
// TODO: No structs may currently be marked noundef
diff --git a/clang/test/CodeGen/indirect-noundef.cpp b/clang/test/CodeGen/indirect-noundef.cpp
--- a/clang/test/CodeGen/indirect-noundef.cpp
+++ b/clang/test/CodeGen/indirect-noundef.cpp
@@ -1,4 +1,5 @@
// RUN: %clang -cc1 -x c++ -triple x86_64-unknown-unknown -O0 -emit-llvm -enable-noundef-analysis -o - %s | FileCheck %s
+// RUN: %clang -cc1 -x c++ -triple x86_64-unknown-unknown -O0 -emit-llvm -fsanitize-memory-param-retval -o - %s | FileCheck %s
union u1 {
int val;