diff --git a/include/llvm/Analysis/CmpInstAnalysis.h b/include/llvm/Analysis/CmpInstAnalysis.h
index 1079d5abc7f..3cc69d9fea2 100644
--- a/include/llvm/Analysis/CmpInstAnalysis.h
+++ b/include/llvm/Analysis/CmpInstAnalysis.h
@@ -64,7 +64,8 @@ namespace llvm {
   /// returned predicate is either == or !=. Returns false if decomposition
   /// fails.
   bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
-                            Value *&X, APInt &Mask);
+                            Value *&X, APInt &Mask,
+                            bool LookThroughTrunc = true);
 
 } // end namespace llvm
 
diff --git a/lib/Analysis/CmpInstAnalysis.cpp b/lib/Analysis/CmpInstAnalysis.cpp
index c879b8729dc..159c1a2d135 100644
--- a/lib/Analysis/CmpInstAnalysis.cpp
+++ b/lib/Analysis/CmpInstAnalysis.cpp
@@ -66,9 +66,11 @@ bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
 
 bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
                                 CmpInst::Predicate &Pred,
-                                Value *&X, APInt &Mask) {
+                                Value *&X, APInt &Mask, bool LookThruTrunc) {
+  using namespace PatternMatch;
+
   const APInt *C;
-  if (!match(RHS, PatternMatch::m_APInt(C)))
+  if (!match(RHS, m_APInt(C)))
     return false;
 
   switch (Pred) {
@@ -132,6 +134,11 @@ bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
     break;
   }
 
-  X = LHS;
+  if (LookThruTrunc && match(LHS, m_Trunc(m_Value(X)))) {
+    Mask = Mask.zext(X->getType()->getScalarSizeInBits());
+  } else {
+    X = LHS;
+  }
+
   return true;
 }
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index d155f6b4803..94d71817049 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -3629,19 +3629,6 @@ static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
   if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
     return nullptr;
 
-  unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
-  if (!BitWidth)
-    return nullptr;
-
-  Value *ExtX;
-  if (match(X, m_Trunc(m_Value(ExtX))) &&
-      (ExtX == TrueVal || ExtX == FalseVal)) {
-    // icmp slt (trunc X), 0  <--> icmp ne (and X, C), 0
-    // icmp sgt (trunc X), -1 <--> icmp eq (and X, C), 0
-    X = ExtX;
-    Mask = Mask.zext(BitWidth);
-  }
-
   return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
                                Pred == ICmpInst::ICMP_EQ);
 }
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 11602ab101e..83aeda5935e 100644
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -724,7 +724,7 @@ Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
       ICmpInst::Predicate Pred = ICI->getPredicate();
       Value *X;
       APInt Mask;
-      if (decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) {
+      if (decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask, false)) {
         if (Mask.isSignMask()) {
           assert(X == CmpLHS && "Expected to use the compare input directly");
           assert(ICmpInst::isEquality(Pred) && "Expected equality predicate");
diff --git a/test/Transforms/InstCombine/bit-checks.ll b/test/Transforms/InstCombine/bit-checks.ll
index 3be67690431..1ecd305e807 100644
--- a/test/Transforms/InstCombine/bit-checks.ll
+++ b/test/Transforms/InstCombine/bit-checks.ll
@@ -520,12 +520,9 @@ define i32 @main7g(i32 %argc, i32 %argc2, i32 %argc3, i32 %argc4, i32 %argc5) {
 
 define i32 @main8(i32 %argc) {
 ; CHECK-LABEL: @main8(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -539,12 +536,9 @@ define i32 @main8(i32 %argc) {
 
 define i32 @main9(i32 %argc) {
 ; CHECK-LABEL: @main9(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 192
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -558,12 +552,9 @@ define i32 @main9(i32 %argc) {
 
 define i32 @main10(i32 %argc) {
 ; CHECK-LABEL: @main10(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -577,12 +568,9 @@ define i32 @main10(i32 %argc) {
 
 define i32 @main11(i32 %argc) {
 ; CHECK-LABEL: @main11(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 192
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -596,12 +584,9 @@ define i32 @main11(i32 %argc) {
 
 define i32 @main12(i32 %argc) {
 ; CHECK-LABEL: @main12(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp slt i16 [[TRUNC]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -615,12 +600,9 @@ define i32 @main12(i32 %argc) {
 
 define i32 @main13(i32 %argc) {
 ; CHECK-LABEL: @main13(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp slt i16 [[TRUNC]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 32896
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -634,12 +616,9 @@ define i32 @main13(i32 %argc) {
 
 define i32 @main14(i32 %argc) {
 ; CHECK-LABEL: @main14(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp sgt i16 [[TRUNC]], -1
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -653,12 +632,9 @@ define i32 @main14(i32 %argc) {
 
 define i32 @main15(i32 %argc) {
 ; CHECK-LABEL: @main15(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp sgt i16 [[TRUNC]], -1
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 32896
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16