Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4392,6 +4392,39 @@
   return nullptr;
 }
 
+/// This simplifies:
+///  select (icmp eq (and X, C), 0), 0, (shl X, K)
+///    or
+///  select (icmp ne (and X, C), 0), (shl X, K), 0
+///    iff C is a mask and the number of its leading zeros is equal to K.
+/// To the following:
+///  shl X, K
+static Value *simplifySelectICmpAndZeroShl(Value *ICmp, Value *TrueVal,
+                                           Value *FalseVal) {
+  ICmpInst::Predicate Pred;
+  Value *AndVal;
+  if (!match(ICmp, m_ICmp(Pred, m_Value(AndVal), m_Zero())))
+    return nullptr;
+
+  const APInt *K;
+  Value *X;
+  if ((Pred == ICmpInst::ICMP_EQ && match(TrueVal, m_Zero()) &&
+       match(FalseVal, m_Shl(m_Value(X), m_APInt(K)))) ||
+      (Pred == ICmpInst::ICMP_NE && match(FalseVal, m_Zero()) &&
+       match(TrueVal, m_Shl(m_Value(X), m_APInt(K))))) {
+    const APInt *C;
+    if (!match(AndVal, m_And(m_Specific(X), m_APInt(C))))
+      return nullptr;
+
+    if (!C->isMask() || (int64_t)C->countLeadingZeros() != K->getSExtValue())
+      return nullptr;
+
+    return Pred == ICmpInst::ICMP_EQ ? FalseVal : TrueVal;
+  }
+
+  return nullptr;
+}
+
 static Value *simplifyCmpSelOfMaxMin(Value *CmpLHS, Value *CmpRHS,
                                      ICmpInst::Predicate Pred, Value *TVal,
                                      Value *FVal) {
@@ -4484,6 +4517,9 @@
                                          Value *FalseVal,
                                          const SimplifyQuery &Q,
                                          unsigned MaxRecurse) {
+  if (Value *V = simplifySelectICmpAndZeroShl(CondVal, TrueVal, FalseVal))
+    return V;
+
   ICmpInst::Predicate Pred;
   Value *CmpLHS, *CmpRHS;
   if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
Index: llvm/test/Transforms/InstSimplify/select.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/select.ll
+++ llvm/test/Transforms/InstSimplify/select.ll
@@ -1347,11 +1347,8 @@
 
 define i32 @select_icmp_and_shl(i32 %x) {
 ; CHECK-LABEL: @select_icmp_and_shl(
-; CHECK-NEXT:    [[SHL_MASK:%.*]] = and i32 [[X:%.*]], 1073741823
-; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i32 [[SHL_MASK]], 0
-; CHECK-NEXT:    [[MUL:%.*]] = shl i32 [[X]], 2
-; CHECK-NEXT:    [[COND:%.*]] = select i1 [[TOBOOL_NOT]], i32 0, i32 [[MUL]]
-; CHECK-NEXT:    ret i32 [[COND]]
+; CHECK-NEXT:    [[MUL:%.*]] = shl i32 [[X:%.*]], 2
+; CHECK-NEXT:    ret i32 [[MUL]]
 ;
   %shl.mask = and i32 %x, 1073741823
   %tobool.not = icmp eq i32 %shl.mask, 0
@@ -1362,11 +1359,8 @@
 
 define <2 x i32> @select_icmp_and_shl_vect(<2 x i32> %x) {
 ; CHECK-LABEL: @select_icmp_and_shl_vect(
-; CHECK-NEXT:    [[SHL_MASK:%.*]] = and <2 x i32> [[X:%.*]], <i32 1073741823, i32 1073741823>
-; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq <2 x i32> [[SHL_MASK]], zeroinitializer
-; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X]], <i32 2, i32 2>
-; CHECK-NEXT:    [[COND:%.*]] = select <2 x i1> [[TOBOOL_NOT]], <2 x i32> zeroinitializer, <2 x i32> [[MUL]]
-; CHECK-NEXT:    ret <2 x i32> [[COND]]
+; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 2, i32 2>
+; CHECK-NEXT:    ret <2 x i32> [[MUL]]
 ;
   %shl.mask = and <2 x i32> %x, <i32 1073741823, i32 1073741823>
   %tobool.not = icmp eq <2 x i32> %shl.mask, zeroinitializer
@@ -1377,11 +1371,8 @@
 
 define i32 @select_icmp_and_shl2(i32 %x) {
 ; CHECK-LABEL: @select_icmp_and_shl2(
-; CHECK-NEXT:    [[SHL_MASK:%.*]] = and i32 [[X:%.*]], 1073741823
-; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp ne i32 [[SHL_MASK]], 0
-; CHECK-NEXT:    [[MUL:%.*]] = shl i32 [[X]], 2
-; CHECK-NEXT:    [[COND:%.*]] = select i1 [[TOBOOL_NOT]], i32 [[MUL]], i32 0
-; CHECK-NEXT:    ret i32 [[COND]]
+; CHECK-NEXT:    [[MUL:%.*]] = shl i32 [[X:%.*]], 2
+; CHECK-NEXT:    ret i32 [[MUL]]
 ;
   %shl.mask = and i32 %x, 1073741823
   %tobool.not = icmp ne i32 %shl.mask, 0
@@ -1392,11 +1383,8 @@
 
 define <2 x i32> @select_icmp_and_shl2_vect(<2 x i32> %x) {
 ; CHECK-LABEL: @select_icmp_and_shl2_vect(
-; CHECK-NEXT:    [[SHL_MASK:%.*]] = and <2 x i32> [[X:%.*]], <i32 1073741823, i32 1073741823>
-; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp ne <2 x i32> [[SHL_MASK]], zeroinitializer
-; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X]], <i32 2, i32 2>
-; CHECK-NEXT:    [[COND:%.*]] = select <2 x i1> [[TOBOOL_NOT]], <2 x i32> [[MUL]], <2 x i32> zeroinitializer
-; CHECK-NEXT:    ret <2 x i32> [[COND]]
+; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 2, i32 2>
+; CHECK-NEXT:    ret <2 x i32> [[MUL]]
 ;
   %shl.mask = and <2 x i32> %x, <i32 1073741823, i32 1073741823>
   %tobool.not = icmp ne <2 x i32> %shl.mask, zeroinitializer