Index: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3778,29 +3778,36 @@
   if (Value *NI = pushFreezeToPreventPoisonFromPropagating(I))
     return replaceInstUsesWith(I, NI);
 
-  if (match(Op0, m_Undef())) {
-    // If I is freeze(undef), check its uses and fold it to a fixed constant.
-    // - or: pick -1
-    // - select's condition: if the true value is constant, choose it by making
-    //                       the condition true.
-    // - default: pick 0
+  // If I is freeze(undef), check its uses and fold it to a fixed constant.
+  // - or: pick -1
+  // - select's condition: if the true value is constant, choose it by making
+  //                       the condition true.
+  // - default: pick 0
+  auto getUndefReplacement = [&I](Type *Ty) {
     Constant *BestValue = nullptr;
-    Constant *NullValue = Constant::getNullValue(I.getType());
+    Constant *NullValue = Constant::getNullValue(Ty);
     for (const auto *U : I.users()) {
       Constant *C = NullValue;
-
       if (match(U, m_Or(m_Value(), m_Value())))
-        C = ConstantInt::getAllOnesValue(I.getType());
+        C = ConstantInt::getAllOnesValue(Ty);
       else if (match(U, m_Select(m_Specific(&I), m_Constant(), m_Value())))
-        C = ConstantInt::getTrue(I.getType());
+        C = ConstantInt::getTrue(Ty);
 
       if (!BestValue)
         BestValue = C;
       else if (BestValue != C)
         BestValue = NullValue;
     }
+    return BestValue;
+  };
 
-    return replaceInstUsesWith(I, BestValue);
+  if (match(Op0, m_Undef()))
+    return replaceInstUsesWith(I, getUndefReplacement(I.getType()));
+
+  Constant *C;
+  if (match(Op0, m_Constant(C)) && C->containsUndefOrPoisonElement()) {
+    Constant *ReplaceC = getUndefReplacement(I.getType()->getScalarType());
+    return replaceInstUsesWith(I, Constant::replaceUndefsWith(C, ReplaceC));
   }
 
   // Replace all dominated uses of Op to freeze(Op).
Index: llvm/test/Transforms/InstCombine/freeze-phi.ll
===================================================================
--- llvm/test/Transforms/InstCombine/freeze-phi.ll
+++ llvm/test/Transforms/InstCombine/freeze-phi.ll
@@ -51,10 +51,9 @@
 ; CHECK:       A:
 ; CHECK-NEXT:    br label [[C:%.*]]
 ; CHECK:       B:
-; CHECK-NEXT:    [[PHI_FR:%.*]] = freeze <2 x i32> <i32 2, i32 undef>
 ; CHECK-NEXT:    br label [[C]]
 ; CHECK:       C:
-; CHECK-NEXT:    [[Y:%.*]] = phi <2 x i32> [ <i32 0, i32 1>, [[A]] ], [ [[PHI_FR]], [[B]] ]
+; CHECK-NEXT:    [[Y:%.*]] = phi <2 x i32> [ <i32 0, i32 1>, [[A]] ], [ <i32 2, i32 0>, [[B]] ]
 ; CHECK-NEXT:    ret <2 x i32> [[Y]]
 ;
   br i1 %cond, label %A, label %B
Index: llvm/test/Transforms/InstCombine/freeze.ll
===================================================================
--- llvm/test/Transforms/InstCombine/freeze.ll
+++ llvm/test/Transforms/InstCombine/freeze.ll
@@ -89,8 +89,7 @@
 
 define <3 x i4> @partial_undef_vec() {
 ; CHECK-LABEL: @partial_undef_vec(
-; CHECK-NEXT:    [[F:%.*]] = freeze <3 x i4> <i4 poison, i4 1, i4 undef>
-; CHECK-NEXT:    ret <3 x i4> [[F]]
+; CHECK-NEXT:    ret <3 x i4> <i4 0, i4 1, i4 0>
 ;
   %f = freeze <3 x i4> <i4 poison, i4 1, i4 undef>
   ret <3 x i4> %f
Index: llvm/test/Transforms/InstCombine/select.ll
===================================================================
--- llvm/test/Transforms/InstCombine/select.ll
+++ llvm/test/Transforms/InstCombine/select.ll
@@ -2633,9 +2633,7 @@
 
 define <2 x i8> @partial_cond_freeze_constant_true_val_vec(<2 x i8> %x) {
 ; CHECK-LABEL: @partial_cond_freeze_constant_true_val_vec(
-; CHECK-NEXT:    [[COND_FR:%.*]] = freeze <2 x i1> <i1 true, i1 undef>
-; CHECK-NEXT:    [[S:%.*]] = select <2 x i1> [[COND_FR]], <2 x i8> <i8 1, i8 2>, <2 x i8> [[X:%.*]]
-; CHECK-NEXT:    ret <2 x i8> [[S]]
+; CHECK-NEXT:    ret <2 x i8> <i8 1, i8 2>
 ;
   %cond.fr = freeze <2 x i1> <i1 true, i1 undef>
   %s = select <2 x i1> %cond.fr, <2 x i8> <i8 1, i8 2>, <2 x i8> %x
@@ -2644,9 +2642,8 @@
 
 define <2 x i8> @partial_cond_freeze_constant_false_val_vec(<2 x i8> %x) {
 ; CHECK-LABEL: @partial_cond_freeze_constant_false_val_vec(
-; CHECK-NEXT:    [[COND_FR:%.*]] = freeze <2 x i1> <i1 true, i1 undef>
-; CHECK-NEXT:    [[S:%.*]] = select <2 x i1> [[COND_FR]], <2 x i8> [[X:%.*]], <2 x i8> <i8 1, i8 2>
-; CHECK-NEXT:    ret <2 x i8> [[S]]
+; CHECK-NEXT:    [[S1:%.*]] = insertelement <2 x i8> [[X:%.*]], i8 2, i64 1
+; CHECK-NEXT:    ret <2 x i8> [[S1]]
 ;
   %cond.fr = freeze <2 x i1> <i1 true, i1 undef>
   %s = select <2 x i1> %cond.fr, <2 x i8> %x, <2 x i8> <i8 1, i8 2>
@@ -2655,9 +2652,7 @@
 
 define <2 x i8> @partial_cond_freeze_both_arms_constant_vec() {
 ; CHECK-LABEL: @partial_cond_freeze_both_arms_constant_vec(
-; CHECK-NEXT:    [[COND_FR:%.*]] = freeze <2 x i1> <i1 false, i1 undef>
-; CHECK-NEXT:    [[S:%.*]] = select <2 x i1> [[COND_FR]], <2 x i8> <i8 1, i8 2>, <2 x i8> <i8 42, i8 43>
-; CHECK-NEXT:    ret <2 x i8> [[S]]
+; CHECK-NEXT:    ret <2 x i8> <i8 42, i8 2>
 ;
   %cond.fr = freeze <2 x i1> <i1 false, i1 undef>
   %s = select <2 x i1> %cond.fr, <2 x i8> <i8 1, i8 2>, <2 x i8> <i8 42, i8 43>