diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index b709ccc3c35a7d..224d98d5c4f99d 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -6678,6 +6678,15 @@ void LoopVectorizationCostModel::collectValuesToIgnore() {
 
   SmallVector<Value *, 4> DeadInterleavePointerOps;
   SmallVector<Value *, 4> DeadOps;
+
+  // If a scalar epilogue is required, users outside the loop won't use
+  // live-outs from the vector loop but from the scalar epilogue. Ignore them if
+  // that is the case.
+  bool RequiresScalarEpilogue = requiresScalarEpilogue(true);
+  auto IsLiveOutDead = [this, RequiresScalarEpilogue](User *U) {
+    return RequiresScalarEpilogue &&
+           !TheLoop->contains(cast<Instruction>(U)->getParent());
+  };
   for (BasicBlock *BB : TheLoop->blocks())
     for (Instruction &I : *BB) {
       // Find all stores to invariant variables. Since they are going to sink
@@ -6693,8 +6702,9 @@ void LoopVectorizationCostModel::collectValuesToIgnore() {
       // Add instructions that would be trivially dead and are only used by
       // values already ignored to DeadOps to seed worklist.
       if (wouldInstructionBeTriviallyDead(&I, TLI) &&
-          all_of(I.users(), [this](User *U) {
-            return VecValuesToIgnore.contains(U) || ValuesToIgnore.contains(U);
+          all_of(I.users(), [this, IsLiveOutDead](User *U) {
+            return VecValuesToIgnore.contains(U) ||
+                   ValuesToIgnore.contains(U) || IsLiveOutDead(U);
           }))
         DeadOps.push_back(&I);
 
@@ -6727,16 +6737,22 @@ void LoopVectorizationCostModel::collectValuesToIgnore() {
 
   // Mark ops that would be trivially dead and are only used by ignored
   // instructions as free.
+  BasicBlock *Header = TheLoop->getHeader();
   for (unsigned I = 0; I != DeadOps.size(); ++I) {
     auto *Op = dyn_cast<Instruction>(DeadOps[I]);
     // Skip any op that shouldn't be considered dead.
     if (!Op || !TheLoop->contains(Op) ||
+        (isa<PHINode>(Op) && Op->getParent() == Header) ||
         !wouldInstructionBeTriviallyDead(Op, TLI) ||
-        any_of(Op->users(), [this](User *U) {
-          return !VecValuesToIgnore.contains(U) && !ValuesToIgnore.contains(U);
+        any_of(Op->users(), [this, IsLiveOutDead](User *U) {
+          return !VecValuesToIgnore.contains(U) && ValuesToIgnore.contains(U) &&
+                 !IsLiveOutDead(U);
         }))
       continue;
 
+    if (!TheLoop->contains(Op->getParent()))
+      continue;
+
     // If all of Op's users are in ValuesToIgnore, add it to ValuesToIgnore
     // which applies for both scalar and vector versions. Otherwise it is only
     // dead in vector versions, so only add it to VecValuesToIgnore.
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll b/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
index 9db4108de4b0a2..da5db810ec6389 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
@@ -86,9 +86,106 @@ loop:
 exit:
   ret void
 }
+
+; Test case for https://github.com/llvm/llvm-project/issues/100464.
+; Loop with a live-out %l and scalar epilogue required due to an interleave
+; group. As the scalar epilogue is required the live-out is fed from the scalar
+; epilogue and dead in the vector loop.
+define i8 @dead_live_out_due_to_scalar_epilogue_required(ptr %src, ptr %dst) {
+; CHECK-LABEL: define i8 @dead_live_out_due_to_scalar_epilogue_required(
+; CHECK-SAME: ptr [[SRC:%.*]], ptr [[DST:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = call i32 @llvm.vscale.i32()
+; CHECK-NEXT:    [[TMP1:%.*]] = mul i32 [[TMP0]], 4
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @llvm.umax.i32(i32 8, i32 [[TMP1]])
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ule i32 252, [[TMP2]]
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_MEMCHECK:.*]]
+; CHECK:       [[VECTOR_MEMCHECK]]:
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[DST]], i64 1005
+; CHECK-NEXT:    [[SCEVGEP1:%.*]] = getelementptr i8, ptr [[SRC]], i64 1005
+; CHECK-NEXT:    [[BOUND0:%.*]] = icmp ult ptr [[DST]], [[SCEVGEP1]]
+; CHECK-NEXT:    [[BOUND1:%.*]] = icmp ult ptr [[SRC]], [[SCEVGEP]]
+; CHECK-NEXT:    [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
+; CHECK-NEXT:    br i1 [[FOUND_CONFLICT]], label %[[SCALAR_PH]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[TMP3:%.*]] = call i32 @llvm.vscale.i32()
+; CHECK-NEXT:    [[TMP4:%.*]] = mul i32 [[TMP3]], 4
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i32 252, [[TMP4]]
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
+; CHECK-NEXT:    [[TMP6:%.*]] = select i1 [[TMP5]], i32 [[TMP4]], i32 [[N_MOD_VF]]
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i32 252, [[TMP6]]
+; CHECK-NEXT:    [[IND_END:%.*]] = mul i32 [[N_VEC]], 4
+; CHECK-NEXT:    [[TMP7:%.*]] = call i32 @llvm.vscale.i32()
+; CHECK-NEXT:    [[TMP8:%.*]] = mul i32 [[TMP7]], 4
+; CHECK-NEXT:    [[TMP9:%.*]] = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
+; CHECK-NEXT:    [[TMP10:%.*]] = add <vscale x 4 x i32> [[TMP9]], zeroinitializer
+; CHECK-NEXT:    [[TMP11:%.*]] = mul <vscale x 4 x i32> [[TMP10]], shufflevector (<vscale x 4 x i32> insertelement (<vscale x 4 x i32> poison, i32 4, i64 0), <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT:    [[INDUCTION:%.*]] = add <vscale x 4 x i32> zeroinitializer, [[TMP11]]
+; CHECK-NEXT:    [[TMP12:%.*]] = call i32 @llvm.vscale.i32()
+; CHECK-NEXT:    [[TMP13:%.*]] = mul i32 [[TMP12]], 4
+; CHECK-NEXT:    [[TMP14:%.*]] = mul i32 4, [[TMP13]]
+; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 4 x i32> poison, i32 [[TMP14]], i64 0
+; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <vscale x 4 x i32> [[DOTSPLATINSERT]], <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 4 x i32> [ [[INDUCTION]], %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP15:%.*]] = sext <vscale x 4 x i32> [[VEC_IND]] to <vscale x 4 x i64>
+; CHECK-NEXT:    [[TMP16:%.*]] = getelementptr i8, ptr [[DST]], <vscale x 4 x i64> [[TMP15]]
+; CHECK-NEXT:    call void @llvm.masked.scatter.nxv4i8.nxv4p0(<vscale x 4 x i8> zeroinitializer, <vscale x 4 x ptr> [[TMP16]], i32 1, <vscale x 4 x i1> shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> poison, i1 true, i64 0), <vscale x 4 x i1> poison, <vscale x 4 x i32> zeroinitializer)), !alias.scope [[META4:![0-9]+]], !noalias [[META7:![0-9]+]]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP8]]
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 4 x i32> [[VEC_IND]], [[DOTSPLAT]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP17]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[IND_END]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ], [ 0, %[[VECTOR_MEMCHECK]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[IDXPROM:%.*]] = sext i32 [[IV]] to i64
+; CHECK-NEXT:    [[GEP_SRC:%.*]] = getelementptr i8, ptr [[SRC]], i64 [[IDXPROM]]
+; CHECK-NEXT:    [[L:%.*]] = load i8, ptr [[GEP_SRC]], align 1
+; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr i8, ptr [[DST]], i64 [[IDXPROM]]
+; CHECK-NEXT:    store i8 0, ptr [[GEP_DST]], align 1
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[IV]], 1001
+; CHECK-NEXT:    br i1 [[CMP]], label %[[LOOP]], label %[[EXIT:.*]], !llvm.loop [[LOOP10:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[R:%.*]] = phi i8 [ [[L]], %[[LOOP]] ]
+; CHECK-NEXT:    ret i8 [[R]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %idxprom = sext i32 %iv to i64
+  %gep.src = getelementptr i8, ptr %src, i64 %idxprom
+  %l = load i8, ptr %gep.src, align 1
+  %gep.dst = getelementptr i8, ptr %dst, i64 %idxprom
+  store i8 0, ptr %gep.dst, align 1
+  %iv.next = add i32 %iv, 4
+  %cmp = icmp ult i32 %iv, 1001
+  br i1 %cmp, label %loop, label %exit
+
+exit:
+  %r = phi i8 [ %l, %loop ]
+  ret i8 %r
+}
+
+
 ;.
 ; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
 ; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1}
 ; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
 ; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META2]], [[META1]]}
+; CHECK: [[META4]] = !{[[META5:![0-9]+]]}
+; CHECK: [[META5]] = distinct !{[[META5]], [[META6:![0-9]+]]}
+; CHECK: [[META6]] = distinct !{[[META6]], !"LVerDomain"}
+; CHECK: [[META7]] = !{[[META8:![0-9]+]]}
+; CHECK: [[META8]] = distinct !{[[META8]], [[META6]]}
+; CHECK: [[LOOP9]] = distinct !{[[LOOP9]], [[META1]], [[META2]]}
+; CHECK: [[LOOP10]] = distinct !{[[LOOP10]], [[META1]]}
 ;.
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll b/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll
index fc310f41630821..3a14842580425b 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll
@@ -18,6 +18,7 @@ define void @vector_reverse_i64(ptr nocapture noundef writeonly %A, ptr nocaptur
 ; CHECK-NEXT:  LV: Found an induction variable.
 ; CHECK-NEXT:  LV: Did not find one integer induction var.
 ; CHECK-NEXT:  LV: We can vectorize this loop (with a runtime bound check)!
+; CHECK-NEXT:  LV: Loop does not require scalar epilogue
 ; CHECK-NEXT:  LV: Found trip count: 0
 ; CHECK-NEXT:  LV: Scalable vectorization is available
 ; CHECK-NEXT:  LV: The max safe fixed VF is: 67108864.
@@ -222,6 +223,7 @@ define void @vector_reverse_f32(ptr nocapture noundef writeonly %A, ptr nocaptur
 ; CHECK-NEXT:  LV: Found FP op with unsafe algebra.
 ; CHECK-NEXT:  LV: Did not find one integer induction var.
 ; CHECK-NEXT:  LV: We can vectorize this loop (with a runtime bound check)!
+; CHECK-NEXT:  LV: Loop does not require scalar epilogue
 ; CHECK-NEXT:  LV: Found trip count: 0
 ; CHECK-NEXT:  LV: Scalable vectorization is available
 ; CHECK-NEXT:  LV: The max safe fixed VF is: 67108864.