diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -633,8 +633,8 @@
 
   // X + ~X -> -1   since   ~X = -X-1
   Type *Ty = Op0->getType();
-  if (match(Op0, m_Not(m_Specific(Op1))) ||
-      match(Op1, m_Not(m_Specific(Op0))))
+  if (Q.AllowRefinement && (match(Op0, m_Not(m_Specific(Op1))) ||
+                            match(Op1, m_Not(m_Specific(Op0)))))
     return Constant::getAllOnesValue(Ty);
 
   // add nsw/nuw (xor Y, signmask), signmask --> Y
@@ -753,7 +753,7 @@
     return Op0;
 
   // X - X -> 0
-  if (Op0 == Op1)
+  if (Q.AllowRefinement && Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
   // Is this a negation?
@@ -1314,7 +1314,7 @@
     return V;
 
   // X >> X -> 0
-  if (Op0 == Op1)
+  if (Q.AllowRefinement && Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
   // undef >> X -> 0
@@ -1413,7 +1413,7 @@
 
   // all ones >>a X -> -1
   // Do not return Op0 because it may contain undef elements if it's a vector.
-  if (match(Op0, m_AllOnes()))
+  if (Q.AllowRefinement && match(Op0, m_AllOnes()))
     return Constant::getAllOnesValue(Op0->getType());
 
   // (X << A) >> A -> X
@@ -2069,7 +2069,7 @@
     return Op0;
 
   // X & 0 = 0
-  if (match(Op1, m_Zero()))
+  if (Q.AllowRefinement && match(Op1, m_Zero()))
     return Constant::getNullValue(Op0->getType());
 
   // X & -1 = X
@@ -2077,8 +2077,8 @@
     return Op0;
 
   // A & ~A  =  ~A & A  =  0
-  if (match(Op0, m_Not(m_Specific(Op1))) ||
-      match(Op1, m_Not(m_Specific(Op0))))
+  if (Q.AllowRefinement && (match(Op0, m_Not(m_Specific(Op1))) ||
+                            match(Op1, m_Not(m_Specific(Op0)))))
     return Constant::getNullValue(Op0->getType());
 
   // (A | ?) & A = A
@@ -2231,7 +2231,7 @@
   // X | undef -> -1
   // X | -1 = -1
   // Do not return Op1 because it may contain undef elements if it's a vector.
-  if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes()))
+  if (Q.isUndefValue(Op1) || (Q.AllowRefinement && match(Op1, m_AllOnes())))
     return Constant::getAllOnesValue(Op0->getType());
 
   // X | X = X
@@ -2240,8 +2240,8 @@
     return Op0;
 
   // A | ~A  =  ~A | A  =  -1
-  if (match(Op0, m_Not(m_Specific(Op1))) ||
-      match(Op1, m_Not(m_Specific(Op0))))
+  if (Q.AllowRefinement && (match(Op0, m_Not(m_Specific(Op1))) ||
+                            match(Op1, m_Not(m_Specific(Op0)))))
     return Constant::getAllOnesValue(Op0->getType());
 
   // (A & ?) | A = A
@@ -2413,12 +2413,12 @@
     return Op0;
 
   // A ^ A = 0
-  if (Op0 == Op1)
+  if (Q.AllowRefinement && Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
   // A ^ ~A  =  ~A ^ A  =  -1
-  if (match(Op0, m_Not(m_Specific(Op1))) ||
-      match(Op1, m_Not(m_Specific(Op0))))
+  if (Q.AllowRefinement && (match(Op0, m_Not(m_Specific(Op1))) ||
+                            match(Op1, m_Not(m_Specific(Op0)))))
     return Constant::getAllOnesValue(Op0->getType());
 
   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor))
@@ -3437,7 +3437,7 @@
 
   // icmp X, X -> true/false
   // icmp X, undef -> true/false because undef could be X.
-  if (LHS == RHS || Q.isUndefValue(RHS))
+  if (Q.AllowRefinement && (LHS == RHS || Q.isUndefValue(RHS)))
     return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
 
   if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
@@ -3770,7 +3770,7 @@
   }
 
   // fcmp x,x -> true/false.  Not all compares are foldable.
-  if (LHS == RHS) {
+  if (Q.AllowRefinement && LHS == RHS) {
     if (CmpInst::isTrueWhenEqual(Pred))
       return getTrue(RetTy);
     if (CmpInst::isFalseWhenEqual(Pred))
diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -899,10 +899,13 @@
   ret i32 %cond
 }
 
+; This cannot be optimized to 'ret (and %x, %y)' because %y might be poison.
 define i32 @test57(i32 %x, i32 %y) {
 ; CHECK-LABEL: @test57(
 ; CHECK-NEXT:    [[AND:%.*]] = and i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    ret i32 [[AND]]
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT:    [[DOTAND:%.*]] = select i1 [[TOBOOL]], i32 0, i32 [[AND]]
+; CHECK-NEXT:    ret i32 [[DOTAND]]
 ;
   %and = and i32 %x, %y
   %tobool = icmp eq i32 %x, 0
@@ -2680,7 +2683,7 @@
 define i32 @pr47322_more_poisonous_replacement(i32 %arg) {
 ; CHECK-LABEL: @pr47322_more_poisonous_replacement(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[ARG:%.*]], 0
-; CHECK-NEXT:    [[TRAILING:%.*]] = call i32 @llvm.cttz.i32(i32 [[ARG]], i1 immarg true), [[RNG0:!range !.*]]
+; CHECK-NEXT:    [[TRAILING:%.*]] = call i32 @llvm.cttz.i32(i32 [[ARG]], i1 immarg true), !range [[RNG0:![0-9]+]]
 ; CHECK-NEXT:    [[SHIFTED:%.*]] = lshr i32 [[ARG]], [[TRAILING]]
 ; CHECK-NEXT:    [[R1_SROA_0_1:%.*]] = select i1 [[CMP]], i32 0, i32 [[SHIFTED]]
 ; CHECK-NEXT:    ret i32 [[R1_SROA_0_1]]