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
@@ -4679,7 +4679,7 @@
     } else {
       SRetPtr = CreateMemTemp(RetTy, "tmp", &SRetAlloca);
       if (HaveInsertPoint() && ReturnValue.isUnused()) {
-        uint64_t size =
+        llvm::TypeSize size =
             CGM.getDataLayout().getTypeAllocSize(ConvertTypeForMem(RetTy));
         UnusedReturnSizePtr = EmitLifetimeStart(size, SRetAlloca.getPointer());
       }
@@ -4840,7 +4840,7 @@
           IRCallArgs[FirstIRArg] = AI.getPointer();
 
           // Emit lifetime markers for the temporary alloca.
-          uint64_t ByvalTempElementSize =
+          llvm::TypeSize ByvalTempElementSize =
               CGM.getDataLayout().getTypeAllocSize(AI.getElementType());
           llvm::Value *LifetimeSize =
               EmitLifetimeStart(ByvalTempElementSize, AI.getPointer());
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1317,11 +1317,15 @@
 /// Emit a lifetime.begin marker if some criteria are satisfied.
 /// \return a pointer to the temporary size Value if a marker was emitted, null
 /// otherwise
-llvm::Value *CodeGenFunction::EmitLifetimeStart(uint64_t Size,
+llvm::Value *CodeGenFunction::EmitLifetimeStart(llvm::TypeSize Size,
                                                 llvm::Value *Addr) {
   if (!ShouldEmitLifetimeMarkers)
     return nullptr;
 
+  // Use -1 as the unknown size.
+  if (Size.isScalable())
+    Size = llvm::TypeSize::Fixed(-1);
+
   assert(Addr->getType()->getPointerAddressSpace() ==
              CGM.getDataLayout().getAllocaAddrSpace() &&
          "Pointer should be in alloca address space");
@@ -1551,9 +1555,7 @@
           llvm::TypeSize size =
               CGM.getDataLayout().getTypeAllocSize(allocaTy);
           emission.SizeForLifetimeMarkers =
-              size.isScalable() ? EmitLifetimeStart(-1, AllocaAddr.getPointer())
-                                : EmitLifetimeStart(size.getFixedSize(),
-                                                    AllocaAddr.getPointer());
+              EmitLifetimeStart(size, AllocaAddr.getPointer());
         }
       } else {
         assert(!emission.useLifetimeMarkers());
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -276,7 +276,7 @@
     RetAddr = Dest.getAddress();
   } else {
     RetAddr = CGF.CreateMemTemp(RetTy, "tmp", &RetAllocaAddr);
-    uint64_t Size =
+    llvm::TypeSize Size =
         CGF.CGM.getDataLayout().getTypeAllocSize(CGF.ConvertTypeForMem(RetTy));
     LifetimeSizePtr = CGF.EmitLifetimeStart(Size, RetAllocaAddr.getPointer());
     if (LifetimeSizePtr) {
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2872,7 +2872,7 @@
   void EmitSehTryScopeBegin();
   void EmitSehTryScopeEnd();
 
-  llvm::Value *EmitLifetimeStart(uint64_t Size, llvm::Value *Addr);
+  llvm::Value *EmitLifetimeStart(llvm::TypeSize Size, llvm::Value *Addr);
   void EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr);
 
   llvm::Value *EmitCXXNewExpr(const CXXNewExpr *E);
diff --git a/clang/test/CodeGen/RISCV/riscv-v-lifetime.cpp b/clang/test/CodeGen/RISCV/riscv-v-lifetime.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/RISCV/riscv-v-lifetime.cpp
@@ -0,0 +1,30 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
+// REQUIRES: riscv-registered-target
+// RUN: %clang_cc1 -std=c++11 -triple riscv64 -target-feature +experimental-v \
+// RUN:   -emit-llvm -O1 -o - %s | FileCheck %s
+
+#include <riscv_vector.h>
+
+template <typename T>
+void Foo(T &&);
+
+template <typename T>
+T Baz();
+
+// CHECK-LABEL: @_Z4Testv(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[REF_TMP:%.*]] = alloca <vscale x 2 x i32>, align 8
+// CHECK-NEXT:    [[TMP0:%.*]] = bitcast <vscale x 2 x i32>* [[REF_TMP]] to i8*
+// CHECK-NEXT:    call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull [[TMP0]]) #[[ATTR3:[0-9]+]]
+// CHECK-NEXT:    [[CALL:%.*]] = call <vscale x 2 x i32> @_Z3BazIu15__rvv_int32m1_tET_v() #[[ATTR3]]
+// CHECK-NEXT:    store <vscale x 2 x i32> [[CALL]], <vscale x 2 x i32>* [[REF_TMP]], align 8, !tbaa [[TBAA4:![0-9]+]]
+// CHECK-NEXT:    call void @_Z3FooIRKu15__rvv_int32m1_tEvOT_(<vscale x 2 x i32>* nonnull align 4 [[REF_TMP]]) #[[ATTR3]]
+// CHECK-NEXT:    [[TMP1:%.*]] = load <vscale x 2 x i32>, <vscale x 2 x i32>* [[REF_TMP]], align 8, !tbaa [[TBAA4]]
+// CHECK-NEXT:    call void @llvm.lifetime.end.p0i8(i64 -1, i8* nonnull [[TMP0]]) #[[ATTR3]]
+// CHECK-NEXT:    ret <vscale x 2 x i32> [[TMP1]]
+//
+vint32m1_t Test() {
+  const vint32m1_t &a = Baz<vint32m1_t>();
+  Foo(a);
+  return a;
+}