diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2043,6 +2043,8 @@
   switch (I->getOpcode()) {
   case Instruction::ZExt:
     return isKnownToBeAPowerOfTwo(I->getOperand(0), OrZero, Depth, Q);
+  case Instruction::Trunc:
+    return OrZero && isKnownToBeAPowerOfTwo(I->getOperand(0), OrZero, Depth, Q);
   case Instruction::Shl:
     if (OrZero || Q.IIQ.hasNoUnsignedWrap(I) || Q.IIQ.hasNoSignedWrap(I))
       return isKnownToBeAPowerOfTwo(I->getOperand(0), OrZero, Depth, Q);
diff --git a/llvm/test/Analysis/ValueTracking/known-power-of-two.ll b/llvm/test/Analysis/ValueTracking/known-power-of-two.ll
--- a/llvm/test/Analysis/ValueTracking/known-power-of-two.ll
+++ b/llvm/test/Analysis/ValueTracking/known-power-of-two.ll
@@ -36,7 +36,8 @@
 ; CHECK-SAME: (i16 [[X:%.*]], i8 [[Y:%.*]]) {
 ; CHECK-NEXT:    [[XP2:%.*]] = shl i16 4, [[X]]
 ; CHECK-NEXT:    [[XX:%.*]] = trunc i16 [[XP2]] to i8
-; CHECK-NEXT:    [[R:%.*]] = urem i8 [[Y]], [[XX]]
+; CHECK-NEXT:    [[TMP1:%.*]] = add i8 [[XX]], -1
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[TMP1]], [[Y]]
 ; CHECK-NEXT:    ret i8 [[R]]
 ;
   %xp2 = shl i16 4, %x