diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -2618,13 +2618,32 @@
 
   if (SelType->isIntOrIntVectorTy(1) &&
       TrueVal->getType() == CondVal->getType()) {
-    if (match(TrueVal, m_One()) &&
-        (EnableUnsafeSelectTransform || impliesPoison(FalseVal, CondVal))) {
+    auto IsSafeToConvert = [&](Value *OtherVal) {
+      if (impliesPoison(OtherVal, CondVal))
+        return true;
+
+      if (!EnableUnsafeSelectTransform)
+        return false;
+
+      // We block this transformation if OtherVal or its operand can create
+      // poison. See PR49688
+      if (auto *Op = dyn_cast<Operator>(OtherVal)) {
+        if (canCreatePoison(Op))
+          return false;
+        if (propagatesPoison(Op) &&
+            llvm::any_of(Op->operand_values(), [](Value *V) {
+              return isa<Operator>(V) ? canCreatePoison(cast<Operator>(V))
+                                      : false;
+            }))
+          return false;
+      }
+      return true;
+    };
+    if (match(TrueVal, m_One()) && IsSafeToConvert(FalseVal)) {
       // Change: A = select B, true, C --> A = or B, C
       return BinaryOperator::CreateOr(CondVal, FalseVal);
     }
-    if (match(FalseVal, m_Zero()) &&
-        (EnableUnsafeSelectTransform || impliesPoison(TrueVal, CondVal))) {
+    if (match(FalseVal, m_Zero()) && IsSafeToConvert(TrueVal)) {
       // Change: A = select B, C, false --> A = and B, C
       return BinaryOperator::CreateAnd(CondVal, TrueVal);
     }
diff --git a/llvm/test/Transforms/InstCombine/and-fcmp.ll b/llvm/test/Transforms/InstCombine/and-fcmp.ll
--- a/llvm/test/Transforms/InstCombine/and-fcmp.ll
+++ b/llvm/test/Transforms/InstCombine/and-fcmp.ll
@@ -73,10 +73,13 @@
   ret i1 %r
 }
 
+; TODO: this should be fixed using freeze
 define i1 @PR41069_commute_logical(i1 %z, float %c, float %d) {
 ; CHECK-LABEL: @PR41069_commute_logical(
-; CHECK-NEXT:    [[TMP1:%.*]] = fcmp ninf ord float [[D:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = and i1 [[TMP1]], [[Z:%.*]]
+; CHECK-NEXT:    [[ORD1:%.*]] = fcmp ninf ord float [[C:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[AND:%.*]] = and i1 [[ORD1]], [[Z:%.*]]
+; CHECK-NEXT:    [[ORD2:%.*]] = fcmp reassoc ninf ord float [[D:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[ORD2]], i1 [[AND]], i1 false
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %ord1 = fcmp ninf ord float %c, 0.0
diff --git a/llvm/test/Transforms/InstCombine/onehot_merge.ll b/llvm/test/Transforms/InstCombine/onehot_merge.ll
--- a/llvm/test/Transforms/InstCombine/onehot_merge.ll
+++ b/llvm/test/Transforms/InstCombine/onehot_merge.ll
@@ -468,7 +468,7 @@
 ; CHECK-NEXT:    [[T2:%.*]] = icmp eq i32 [[T1]], 0
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -506,7 +506,7 @@
 ; CHECK-NEXT:    [[T2:%.*]] = icmp ne i32 [[T1]], 0
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp slt i32 [[T3]], 0
-; CHECK-NEXT:    [[OR:%.*]] = and i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 [[T4]], i1 false
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -535,13 +535,15 @@
   ret i1 %or
 }
 
+; %t2 can be poison where as %t0 isn't; merging these two is unsafe.
 define i1 @foo1_and_signbit_lshr_without_shifting_signbit_both_sides_logical(i32 %k, i32 %c1, i32 %c2) {
 ; CHECK-LABEL: @foo1_and_signbit_lshr_without_shifting_signbit_both_sides_logical(
 ; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[K:%.*]], [[C1:%.*]]
+; CHECK-NEXT:    [[T1:%.*]] = icmp sgt i32 [[T0]], -1
 ; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[K]], [[C2:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[T0]], [[T2]]
-; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[TMP1]], -1
-; CHECK-NEXT:    ret i1 [[TMP2]]
+; CHECK-NEXT:    [[T3:%.*]] = icmp sgt i32 [[T2]], -1
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T1]], i1 true, i1 [[T3]]
+; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 %k, %c1
   %t1 = icmp sgt i32 %t0, -1
@@ -567,13 +569,15 @@
   ret i1 %or
 }
 
+; %t2 can be poison where as %t0 isn't; merging these two is unsafe.
 define i1 @foo1_or_signbit_lshr_without_shifting_signbit_both_sides_logical(i32 %k, i32 %c1, i32 %c2) {
 ; CHECK-LABEL: @foo1_or_signbit_lshr_without_shifting_signbit_both_sides_logical(
 ; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[K:%.*]], [[C1:%.*]]
+; CHECK-NEXT:    [[T1:%.*]] = icmp slt i32 [[T0]], 0
 ; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[K]], [[C2:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[T0]], [[T2]]
-; CHECK-NEXT:    [[TMP2:%.*]] = icmp slt i32 [[TMP1]], 0
-; CHECK-NEXT:    ret i1 [[TMP2]]
+; CHECK-NEXT:    [[T3:%.*]] = icmp slt i32 [[T2]], 0
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T1]], i1 [[T3]], i1 false
+; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 %k, %c1
   %t1 = icmp slt i32 %t0, 0
@@ -886,7 +890,7 @@
 ; CHECK-NEXT:    [[T2:%.*]] = icmp eq i32 [[T1]], 0
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -929,7 +933,7 @@
 ; CHECK-NEXT:    [[T2:%.*]] = icmp eq i32 [[T1]], 0
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -972,7 +976,7 @@
 ; CHECK-NEXT:    store i1 [[T2]], i1* [[P:%.*]], align 1
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -1015,7 +1019,7 @@
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    store i32 [[T3]], i32* [[P:%.*]], align 4
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -1058,7 +1062,7 @@
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
 ; CHECK-NEXT:    store i1 [[T4]], i1* [[P:%.*]], align 1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 1, %c1
@@ -1100,7 +1104,7 @@
 ; CHECK-NEXT:    [[T2:%.*]] = icmp eq i32 [[T1]], 0
 ; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[K]], [[C2:%.*]]
 ; CHECK-NEXT:    [[T4:%.*]] = icmp sgt i32 [[T3]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[T2]], [[T4]]
+; CHECK-NEXT:    [[OR:%.*]] = select i1 [[T2]], i1 true, i1 [[T4]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %t0 = shl i32 3, %c1
diff --git a/llvm/test/Transforms/InstCombine/pr49688.ll b/llvm/test/Transforms/InstCombine/pr49688.ll
--- a/llvm/test/Transforms/InstCombine/pr49688.ll
+++ b/llvm/test/Transforms/InstCombine/pr49688.ll
@@ -1,12 +1,15 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
+; %cmp should not vanish
 define i1 @f(i32 %i1) {
 ; CHECK-LABEL: @f(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 7, [[I1:%.*]]
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i32 [[SHR]], [[I1]]
-; CHECK-NEXT:    ret i1 [[TMP0]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I1:%.*]], 0
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 7, [[I1]]
+; CHECK-NEXT:    [[CMP4:%.*]] = icmp slt i32 [[SHR]], [[I1]]
+; CHECK-NEXT:    [[I2:%.*]] = select i1 [[CMP]], i1 true, i1 [[CMP4]]
+; CHECK-NEXT:    ret i1 [[I2]]
 ;
 entry:
   %cmp = icmp slt i32 %i1, 0
@@ -16,11 +19,14 @@
   ret i1 %i2
 }
 
+; %cmp should not vanish
 define i32 @f2(i32 signext %g, i32 zeroext %h) {
 ; CHECK-LABEL: @f2(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[G:%.*]], 0
 ; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 7, [[H:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 [[SHR]], [[G:%.*]]
-; CHECK-NEXT:    [[LOR_EXT:%.*]] = zext i1 [[TMP1]] to i32
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp slt i32 [[SHR]], [[G]]
+; CHECK-NEXT:    [[DOT0:%.*]] = select i1 [[CMP]], i1 true, i1 [[CMP1]]
+; CHECK-NEXT:    [[LOR_EXT:%.*]] = zext i1 [[DOT0]] to i32
 ; CHECK-NEXT:    ret i32 [[LOR_EXT]]
 ;
   %cmp = icmp slt i32 %g, 0
diff --git a/llvm/test/Transforms/InstCombine/signed-truncation-check.ll b/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
--- a/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
+++ b/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
@@ -606,7 +606,7 @@
 ; CHECK-NEXT:    call void @use32(i32 [[T4]])
 ; CHECK-NEXT:    [[T5:%.*]] = icmp eq i32 [[T4]], [[ARG]]
 ; CHECK-NEXT:    call void @use1(i1 [[T5]])
-; CHECK-NEXT:    [[T6:%.*]] = and i1 [[T2]], [[T5]]
+; CHECK-NEXT:    [[T6:%.*]] = select i1 [[T2]], i1 [[T5]], i1 false
 ; CHECK-NEXT:    ret i1 [[T6]]
 ;
   %t1 = trunc i32 %arg to i8
diff --git a/llvm/test/Transforms/InstCombine/widenable-conditions.ll b/llvm/test/Transforms/InstCombine/widenable-conditions.ll
--- a/llvm/test/Transforms/InstCombine/widenable-conditions.ll
+++ b/llvm/test/Transforms/InstCombine/widenable-conditions.ll
@@ -20,7 +20,7 @@
 define i1 @test1_logical(i1 %a, i1 %b) {
 ; CHECK-LABEL: @test1_logical(
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
-; CHECK-NEXT:    [[LHS:%.*]] = and i1 [[WC]], [[B:%.*]]
+; CHECK-NEXT:    [[LHS:%.*]] = select i1 [[B:%.*]], i1 [[WC]], i1 false
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[LHS]], [[A:%.*]]
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
@@ -49,7 +49,7 @@
 define i1 @test1b_logical(i1 %a, i1 %b) {
 ; CHECK-LABEL: @test1b_logical(
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
-; CHECK-NEXT:    [[LHS:%.*]] = and i1 [[WC]], [[B:%.*]]
+; CHECK-NEXT:    [[LHS:%.*]] = select i1 [[B:%.*]], i1 [[WC]], i1 false
 ; CHECK-NEXT:    call void @use(i1 [[LHS]])
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[LHS]], [[A:%.*]]
 ; CHECK-NEXT:    ret i1 [[AND]]
@@ -87,7 +87,7 @@
 ; CHECK-NEXT:    call void @use(i1 [[B:%.*]])
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    call void @use(i1 [[WC]])
-; CHECK-NEXT:    [[LHS:%.*]] = and i1 [[WC]], [[B]]
+; CHECK-NEXT:    [[LHS:%.*]] = select i1 [[B]], i1 [[WC]], i1 false
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[LHS]], [[A]]
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
@@ -147,7 +147,7 @@
 ; CHECK-LABEL: @test3_logical(
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    [[LHS:%.*]] = and i1 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[RHS:%.*]] = and i1 [[WC]], [[C:%.*]]
+; CHECK-NEXT:    [[RHS:%.*]] = select i1 [[C:%.*]], i1 [[WC]], i1 false
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[LHS]], [[RHS]]
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
@@ -178,7 +178,7 @@
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    [[LHS:%.*]] = and i1 [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    [[RHS:%.*]] = and i1 [[WC]], [[C:%.*]]
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[LHS]], [[RHS]]
+; CHECK-NEXT:    [[AND:%.*]] = select i1 [[LHS]], i1 [[RHS]], i1 false
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
   %wc = call i1 @llvm.experimental.widenable.condition()
@@ -225,7 +225,7 @@
 ; CHECK-LABEL: @test6_logical(
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    [[WC2:%.*]] = call i1 @llvm.experimental.widenable.condition()
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[WC]], [[WC2]]
+; CHECK-NEXT:    [[AND:%.*]] = select i1 [[WC]], i1 [[WC2]], i1 false
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
   %wc = call i1 @llvm.experimental.widenable.condition()
@@ -254,7 +254,7 @@
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    call void @use(i1 [[WC]])
 ; CHECK-NEXT:    [[WC2:%.*]] = call i1 @llvm.experimental.widenable.condition()
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[WC]], [[WC2]]
+; CHECK-NEXT:    [[AND:%.*]] = select i1 [[WC]], i1 [[WC2]], i1 false
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
   %wc = call i1 @llvm.experimental.widenable.condition()
@@ -284,7 +284,7 @@
 ; CHECK-NEXT:    [[WC:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    [[WC2:%.*]] = call i1 @llvm.experimental.widenable.condition()
 ; CHECK-NEXT:    call void @use(i1 [[WC2]])
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[WC]], [[WC2]]
+; CHECK-NEXT:    [[AND:%.*]] = select i1 [[WC]], i1 [[WC2]], i1 false
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
   %wc = call i1 @llvm.experimental.widenable.condition()