Index: lib/Transforms/InstCombine/InstCombine.h
===================================================================
--- lib/Transforms/InstCombine/InstCombine.h
+++ lib/Transforms/InstCombine/InstCombine.h
@@ -193,6 +193,8 @@
                               ConstantInt *DivRHS);
   Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
                                  ConstantInt *CI1, ConstantInt *CI2);
+  Instruction *FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A,
+                                 ConstantInt *CI1, ConstantInt *CI2);
   Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,
                                 ICmpInst::Predicate Pred);
   Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
Index: lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1118,6 +1118,49 @@
   return getConstant(false);
 }
 
+/// FoldICmpCstShlCst - Handle "(icmp eq/ne (shl const2, A), const1)" ->
+/// (icmp eq/ne A, TrailingZeros(const1) - TrailingZeros(const2)).
+Instruction *InstCombiner::FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A,
+                                             ConstantInt *CI1,
+                                             ConstantInt *CI2) {
+  assert(I.isEquality() && "Cannot fold icmp gt/lt");
+
+  auto getConstant = [&I, this](bool IsTrue) {
+    if (I.getPredicate() == I.ICMP_NE)
+      IsTrue = !IsTrue;
+    return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), IsTrue));
+  };
+
+  auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
+    if (I.getPredicate() == I.ICMP_NE)
+      Pred = CmpInst::getInversePredicate(Pred);
+    return new ICmpInst(Pred, LHS, RHS);
+  };
+
+  APInt AP1 = CI1->getValue();
+  APInt AP2 = CI2->getValue();
+
+  assert(AP2 != 0 && "Handled in InstSimplify");
+
+  unsigned AP2TrailingZeros = AP2.countTrailingZeros();
+
+  if (!AP1 && AP2TrailingZeros != 0)
+    return getICmp(I.ICMP_UGE, A,
+                   ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros));
+
+  if (AP1 == AP2)
+    return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
+
+  // Get the distance between the lowest bits that are set.
+  int Shift = AP1.countTrailingZeros() - AP2TrailingZeros;
+
+  if (Shift > 0 && AP2.shl(Shift) == AP1)
+    return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
+
+  // Shifting const2 will never be equal to const1.
+  return getConstant(false);
+}
+
 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
 ///
 Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
@@ -2693,13 +2736,17 @@
                           Builder->getInt(CI->getValue()-1));
     }
 
-    // (icmp eq/ne (ashr/lshr const2, A), const1)
     if (I.isEquality()) {
       ConstantInt *CI2;
       if (match(Op0, m_AShr(m_ConstantInt(CI2), m_Value(A))) ||
           match(Op0, m_LShr(m_ConstantInt(CI2), m_Value(A)))) {
+        // (icmp eq/ne (ashr/lshr const2, A), const1)
         return FoldICmpCstShrCst(I, Op0, A, CI, CI2);
       }
+      else if (match(Op0, m_Shl(m_ConstantInt(CI2), m_Value(A)))) {
+        // (icmp eq/ne (shl const2, A), const1)
+        return FoldICmpCstShlCst(I, Op0, A, CI, CI2);
+      }
     }
 
     // If this comparison is a normal comparison, it demands all
Index: test/Transforms/InstCombine/icmp.ll
===================================================================
--- test/Transforms/InstCombine/icmp.ll
+++ test/Transforms/InstCombine/icmp.ll
@@ -1418,3 +1418,64 @@
   %ret = icmp ne i32 %and, 0
   ret i1 %ret
 }
+
+; CHECK-LABEL: @shl_ap1_zero_ap2_non_zero_2
+; CHECK-NEXT: %cmp = icmp ugt i32 %a, 29
+; CHECK-NEXT: ret i1 %cmp
+define i1 @shl_ap1_zero_ap2_non_zero_2(i32 %a) {
+ %shl = shl i32 4, %a
+ %cmp = icmp eq i32 %shl, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_zero_ap2_non_zero_4
+; CHECK-NEXT: %cmp = icmp ugt i32 %a, 30
+; CHECK-NEXT: ret i1 %cmp
+define i1 @shl_ap1_zero_ap2_non_zero_4(i32 %a) {
+ %shl = shl i32 -2, %a
+ %cmp = icmp eq i32 %shl, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_non_zero_ap2_non_zero_both_positive
+; CHECK-NEXT: %cmp = icmp eq i32 %a, 0
+; CHECK-NEXT: ret i1 %cmp
+define i1 @shl_ap1_non_zero_ap2_non_zero_both_positive(i32 %a) {
+ %shl = shl i32 50, %a
+ %cmp = icmp eq i32 %shl, 50
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_non_zero_ap2_non_zero_both_negative
+; CHECK-NEXT: %cmp = icmp eq i32 %a, 0
+; CHECK-NEXT: ret i1 %cmp
+define i1 @shl_ap1_non_zero_ap2_non_zero_both_negative(i32 %a) {
+ %shl = shl i32 -50, %a
+ %cmp = icmp eq i32 %shl, -50
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_non_zero_ap2_non_zero_ap1_1
+; CHECK-NEXT: ret i1 false
+define i1 @shl_ap1_non_zero_ap2_non_zero_ap1_1(i32 %a) {
+ %shl = shl i32 50, %a
+ %cmp = icmp eq i32 %shl, 25
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_non_zero_ap2_non_zero_ap1_2
+; CHECK-NEXT: %cmp = icmp eq i32 %a, 1
+; CHECK-NEXT: ret i1 %cmp
+define i1 @shl_ap1_non_zero_ap2_non_zero_ap1_2(i32 %a) {
+ %shl = shl i32 25, %a
+ %cmp = icmp eq i32 %shl, 50
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @shl_ap1_non_zero_ap2_non_zero_ap1_3
+; CHECK-NEXT: ret i1 false
+define i1 @shl_ap1_non_zero_ap2_non_zero_ap1_3(i32 %a) {
+ %shl = shl i32 26, %a
+ %cmp = icmp eq i32 %shl, 50
+ ret i1 %cmp
+}