Index: include/llvm/IR/IRBuilder.h
===================================================================
--- include/llvm/IR/IRBuilder.h
+++ include/llvm/IR/IRBuilder.h
@@ -2164,10 +2164,11 @@
                                       Value *OffsetValue = nullptr) {
     assert(isa<PointerType>(PtrValue->getType()) &&
            "trying to create an alignment assumption on a non-pointer?");
+    assert(Alignment != 0 && "Invalid Alignment");
     auto *PtrTy = cast<PointerType>(PtrValue->getType());
     Type *IntPtrTy = getIntPtrTy(DL, PtrTy->getAddressSpace());
 
-    Value *Mask = ConstantInt::get(IntPtrTy, Alignment > 0 ? Alignment - 1 : 0);
+    Value *Mask = ConstantInt::get(IntPtrTy, Alignment - 1);
     return CreateAlignmentAssumptionHelper(DL, PtrValue, Mask, IntPtrTy,
                                            OffsetValue);
   }
@@ -2192,13 +2193,7 @@
     if (Alignment->getType() != IntPtrTy)
       Alignment = CreateIntCast(Alignment, IntPtrTy, /*isSigned*/ true,
                                 "alignmentcast");
-    Value *IsPositive =
-        CreateICmp(CmpInst::ICMP_SGT, Alignment,
-                   ConstantInt::get(Alignment->getType(), 0), "ispositive");
-    Value *PositiveMask =
-        CreateSub(Alignment, ConstantInt::get(IntPtrTy, 1), "positivemask");
-    Value *Mask = CreateSelect(IsPositive, PositiveMask,
-                               ConstantInt::get(IntPtrTy, 0), "mask");
+    Value *Mask = CreateSub(Alignment, ConstantInt::get(IntPtrTy, 1), "mask");
 
     return CreateAlignmentAssumptionHelper(DL, PtrValue, Mask, IntPtrTy,
                                            OffsetValue);