diff --git a/include/llvm/Analysis/Loads.h b/include/llvm/Analysis/Loads.h
index b5884ac..9604b25 100644
--- a/include/llvm/Analysis/Loads.h
+++ b/include/llvm/Analysis/Loads.h
@@ -37,7 +37,8 @@
 /// performs context-sensitive analysis and returns true if the pointer is
 /// dereferenceable at the specified instruction.
 bool isDereferenceableAndAlignedPointer(const Value *V, Type *Ty,
-                                        unsigned Align, const DataLayout &DL,
+                                        MaybeAlign Alignment,
+                                        const DataLayout &DL,
                                         const Instruction *CtxI = nullptr,
                                         const DominatorTree *DT = nullptr);
 
@@ -45,7 +46,7 @@
 /// greater or equal than requested. If the context instruction is specified
 /// performs context-sensitive analysis and returns true if the pointer is
 /// dereferenceable at the specified instruction.
-bool isDereferenceableAndAlignedPointer(const Value *V, unsigned Align,
+bool isDereferenceableAndAlignedPointer(const Value *V, Align Alignment,
                                         const APInt &Size, const DataLayout &DL,
                                         const Instruction *CtxI = nullptr,
                                         const DominatorTree *DT = nullptr);
@@ -58,7 +59,7 @@
 /// If it is not obviously safe to load from the specified pointer, we do a
 /// quick local scan of the basic block containing ScanFrom, to determine if
 /// the address is already accessed.
-bool isSafeToLoadUnconditionally(Value *V, unsigned Align, APInt &Size,
+bool isSafeToLoadUnconditionally(Value *V, MaybeAlign Alignment, APInt &Size,
                                  const DataLayout &DL,
                                  Instruction *ScanFrom = nullptr,
                                  const DominatorTree *DT = nullptr);
@@ -82,7 +83,7 @@
 /// If it is not obviously safe to load from the specified pointer, we do a
 /// quick local scan of the basic block containing ScanFrom, to determine if
 /// the address is already accessed.
-bool isSafeToLoadUnconditionally(Value *V, Type *Ty, unsigned Align,
+bool isSafeToLoadUnconditionally(Value *V, Type *Ty, MaybeAlign Alignment,
                                  const DataLayout &DL,
                                  Instruction *ScanFrom = nullptr,
                                  const DominatorTree *DT = nullptr);
diff --git a/lib/Analysis/Loads.cpp b/lib/Analysis/Loads.cpp
index a4fd499..641e92e 100644
--- a/lib/Analysis/Loads.cpp
+++ b/lib/Analysis/Loads.cpp
@@ -50,7 +50,7 @@
 /// Test if V is always a pointer to allocated and suitably aligned memory for
 /// a simple load or store.
 static bool isDereferenceableAndAlignedPointer(
-    const Value *V, unsigned Align, const APInt &Size, const DataLayout &DL,
+    const Value *V, Align Alignment, const APInt &Size, const DataLayout &DL,
     const Instruction *CtxI, const DominatorTree *DT,
     SmallPtrSetImpl<const Value *> &Visited) {
   // Already visited?  Bail out, we've likely hit unreachable code.
@@ -62,8 +62,8 @@
 
   // bitcast instructions are no-ops as far as dereferenceability is concerned.
   if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V))
-    return isDereferenceableAndAlignedPointer(BC->getOperand(0), Align, Size,
-                                              DL, CtxI, DT, Visited);
+    return isDereferenceableAndAlignedPointer(BC->getOperand(0), Alignment,
+                                              Size, DL, CtxI, DT, Visited);
 
   bool CheckForNonNull = false;
   APInt KnownDerefBytes(Size.getBitWidth(),
@@ -76,7 +76,7 @@
       Type *Ty = V->getType();
       assert(Ty->isSized() && "must be sized");
       APInt Offset(DL.getTypeStoreSizeInBits(Ty), 0);
-      return isAligned(V, Offset, llvm::Align(Align), DL);
+      return isAligned(V, Offset, Alignment, DL);
     }
 
   // For GEPs, determine if the indexing lands within the allocated object.
@@ -85,7 +85,8 @@
 
     APInt Offset(DL.getIndexTypeSizeInBits(GEP->getType()), 0);
     if (!GEP->accumulateConstantOffset(DL, Offset) || Offset.isNegative() ||
-        !Offset.urem(APInt(Offset.getBitWidth(), Align)).isMinValue())
+        !Offset.urem(APInt(Offset.getBitWidth(), Alignment.value()))
+             .isMinValue())
       return false;
 
     // If the base pointer is dereferenceable for Offset+Size bytes, then the
@@ -97,72 +98,69 @@
     // Offset and Size may have different bit widths if we have visited an
     // addrspacecast, so we can't do arithmetic directly on the APInt values.
     return isDereferenceableAndAlignedPointer(
-        Base, Align, Offset + Size.sextOrTrunc(Offset.getBitWidth()),
-        DL, CtxI, DT, Visited);
+        Base, Alignment, Offset + Size.sextOrTrunc(Offset.getBitWidth()), DL,
+        CtxI, DT, Visited);
   }
 
   // For gc.relocate, look through relocations
   if (const GCRelocateInst *RelocateInst = dyn_cast<GCRelocateInst>(V))
     return isDereferenceableAndAlignedPointer(
-        RelocateInst->getDerivedPtr(), Align, Size, DL, CtxI, DT, Visited);
+        RelocateInst->getDerivedPtr(), Alignment, Size, DL, CtxI, DT, Visited);
 
   if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
-    return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Align, Size,
-                                              DL, CtxI, DT, Visited);
+    return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Alignment,
+                                              Size, DL, CtxI, DT, Visited);
 
   if (const auto *Call = dyn_cast<CallBase>(V))
     if (auto *RP = getArgumentAliasingToReturnedPointer(Call, true))
-      return isDereferenceableAndAlignedPointer(RP, Align, Size, DL, CtxI, DT,
-                                                Visited);
+      return isDereferenceableAndAlignedPointer(RP, Alignment, Size, DL, CtxI,
+                                                DT, Visited);
 
   // If we don't know, assume the worst.
   return false;
 }
 
-bool llvm::isDereferenceableAndAlignedPointer(const Value *V, unsigned Align,
+bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Align Alignment,
                                               const APInt &Size,
                                               const DataLayout &DL,
                                               const Instruction *CtxI,
                                               const DominatorTree *DT) {
-  assert(Align != 0 && "expected explicitly set alignment");
   // Note: At the moment, Size can be zero.  This ends up being interpreted as
   // a query of whether [Base, V] is dereferenceable and V is aligned (since
   // that's what the implementation happened to do).  It's unclear if this is
   // the desired semantic, but at least SelectionDAG does exercise this case.  
   
   SmallPtrSet<const Value *, 32> Visited;
-  return ::isDereferenceableAndAlignedPointer(V, Align, Size, DL, CtxI, DT,
+  return ::isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT,
                                               Visited);
 }
 
 bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Type *Ty,
-                                              unsigned Align,
+                                              MaybeAlign MA,
                                               const DataLayout &DL,
                                               const Instruction *CtxI,
                                               const DominatorTree *DT) {
+  if (!Ty->isSized())
+    return false;
+  
   // When dereferenceability information is provided by a dereferenceable
   // attribute, we know exactly how many bytes are dereferenceable. If we can
   // determine the exact offset to the attributed variable, we can use that
   // information here.
 
   // Require ABI alignment for loads without alignment specification
-  if (Align == 0)
-    Align = DL.getABITypeAlignment(Ty);
-
-  if (!Ty->isSized())
-    return false;
-  
+  const Align Alignment = DL.getValueOrABITypeAlignment(MA, Ty);
   APInt AccessSize(DL.getIndexTypeSizeInBits(V->getType()),
                    DL.getTypeStoreSize(Ty));
-  return isDereferenceableAndAlignedPointer(V, Align, AccessSize,
-                                            DL, CtxI, DT);
+  return isDereferenceableAndAlignedPointer(V, Alignment, AccessSize, DL, CtxI,
+                                            DT);
 }
 
 bool llvm::isDereferenceablePointer(const Value *V, Type *Ty,
                                     const DataLayout &DL,
                                     const Instruction *CtxI,
                                     const DominatorTree *DT) {
-  return isDereferenceableAndAlignedPointer(V, Ty, 1, DL, CtxI, DT);
+  return isDereferenceableAndAlignedPointer(V, Ty, Align::None(), DL, CtxI, DT);
 }
 
 /// Test if A and B will obviously have the same value.
@@ -204,17 +202,16 @@
 
   APInt EltSize(DL.getIndexTypeSizeInBits(Ptr->getType()),
                 DL.getTypeStoreSize(LI->getType()));
-  unsigned Align = LI->getAlignment();
-  if (Align == 0)
-    Align = DL.getABITypeAlignment(LI->getType());
+  const Align Alignment = DL.getValueOrABITypeAlignment(
+      MaybeAlign(LI->getAlignment()), LI->getType());
 
   Instruction *HeaderFirstNonPHI = L->getHeader()->getFirstNonPHI();
 
   // If given a uniform (i.e. non-varying) address, see if we can prove the
   // access is safe within the loop w/o needing predication.
   if (L->isLoopInvariant(Ptr))
-    return isDereferenceableAndAlignedPointer(Ptr, Align, EltSize, DL,
-                                              HeaderFirstNonPHI, &DT);    
+    return isDereferenceableAndAlignedPointer(Ptr, Alignment, EltSize, DL,
+                                              HeaderFirstNonPHI, &DT);
 
   // Otherwise, check to see if we have a repeating access pattern where we can
   // prove that all accesses are well aligned and dereferenceable.
@@ -245,10 +242,10 @@
   // For the moment, restrict ourselves to the case where the access size is a
   // multiple of the requested alignment and the base is aligned.
   // TODO: generalize if a case found which warrants
-  if (EltSize.urem(Align) != 0)
+  if (EltSize.urem(Alignment.value()) != 0)
     return false;
-  return isDereferenceableAndAlignedPointer(Base, Align, AccessSize,
-                                            DL, HeaderFirstNonPHI, &DT);
+  return isDereferenceableAndAlignedPointer(Base, Alignment, AccessSize, DL,
+                                            HeaderFirstNonPHI, &DT);
 }
 
 /// Check if executing a load of this pointer value cannot trap.
@@ -262,18 +259,17 @@
 ///
 /// This uses the pointee type to determine how many bytes need to be safe to
 /// load from the pointer.
-bool llvm::isSafeToLoadUnconditionally(Value *V, unsigned Align, APInt &Size,
+bool llvm::isSafeToLoadUnconditionally(Value *V, MaybeAlign MA, APInt &Size,
                                        const DataLayout &DL,
                                        Instruction *ScanFrom,
                                        const DominatorTree *DT) {
   // Zero alignment means that the load has the ABI alignment for the target
-  if (Align == 0)
-    Align = DL.getABITypeAlignment(V->getType()->getPointerElementType());
-  assert(isPowerOf2_32(Align));
+  const Align Alignment =
+      DL.getValueOrABITypeAlignment(MA, V->getType()->getPointerElementType());
 
   // If DT is not specified we can't make context-sensitive query
   const Instruction* CtxI = DT ? ScanFrom : nullptr;
-  if (isDereferenceableAndAlignedPointer(V, Align, Size, DL, CtxI, DT))
+  if (isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT))
     return true;
 
   if (!ScanFrom)
@@ -305,7 +301,7 @@
       return false;
 
     Value *AccessedPtr;
-    unsigned AccessedAlign;
+    MaybeAlign MaybeAccessedAlign;
     if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
       // Ignore volatile loads. The execution of a volatile load cannot
       // be used to prove an address is backed by regular memory; it can,
@@ -313,20 +309,21 @@
       if (LI->isVolatile())
         continue;
       AccessedPtr = LI->getPointerOperand();
-      AccessedAlign = LI->getAlignment();
+      MaybeAccessedAlign = MaybeAlign(LI->getAlignment());
     } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
       // Ignore volatile stores (see comment for loads).
       if (SI->isVolatile())
         continue;
       AccessedPtr = SI->getPointerOperand();
-      AccessedAlign = SI->getAlignment();
+      MaybeAccessedAlign = MaybeAlign(SI->getAlignment());
     } else
       continue;
 
     Type *AccessedTy = AccessedPtr->getType()->getPointerElementType();
-    if (AccessedAlign == 0)
-      AccessedAlign = DL.getABITypeAlignment(AccessedTy);
-    if (AccessedAlign < Align)
+
+    const Align AccessedAlign =
+        DL.getValueOrABITypeAlignment(MaybeAccessedAlign, AccessedTy);
+    if (AccessedAlign < Alignment)
       continue;
 
     // Handle trivial cases.
@@ -341,12 +338,12 @@
   return false;
 }
 
-bool llvm::isSafeToLoadUnconditionally(Value *V, Type *Ty, unsigned Align,
+bool llvm::isSafeToLoadUnconditionally(Value *V, Type *Ty, MaybeAlign Alignment,
                                        const DataLayout &DL,
                                        Instruction *ScanFrom,
                                        const DominatorTree *DT) {
   APInt Size(DL.getIndexTypeSizeInBits(V->getType()), DL.getTypeStoreSize(Ty));
-  return isSafeToLoadUnconditionally(V, Align, Size, DL, ScanFrom, DT);
+  return isSafeToLoadUnconditionally(V, Alignment, Size, DL, ScanFrom, DT);
 }
 
   /// DefMaxInstsToScan - the default number of maximum instructions
diff --git a/lib/Analysis/MemDerefPrinter.cpp b/lib/Analysis/MemDerefPrinter.cpp
index 77ebf89..5cf516a 100644
--- a/lib/Analysis/MemDerefPrinter.cpp
+++ b/lib/Analysis/MemDerefPrinter.cpp
@@ -55,8 +55,8 @@
       Value *PO = LI->getPointerOperand();
       if (isDereferenceablePointer(PO, LI->getType(), DL))
         Deref.push_back(PO);
-      if (isDereferenceableAndAlignedPointer(PO, LI->getType(),
-                                             LI->getAlignment(), DL))
+      if (isDereferenceableAndAlignedPointer(
+              PO, LI->getType(), MaybeAlign(LI->getAlignment()), DL))
         DerefAndAligned.insert(PO);
     }
   }
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index c62ec35..bbf3899 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -3938,9 +3938,9 @@
     if (mustSuppressSpeculation(*LI))
       return false;
     const DataLayout &DL = LI->getModule()->getDataLayout();
-    return isDereferenceableAndAlignedPointer(LI->getPointerOperand(),
-                                              LI->getType(), LI->getAlignment(),
-                                              DL, CtxI, DT);
+    return isDereferenceableAndAlignedPointer(
+        LI->getPointerOperand(), LI->getType(), MaybeAlign(LI->getAlignment()),
+        DL, CtxI, DT);
   }
   case Instruction::Call: {
     auto *CI = cast<const CallInst>(Inst);
diff --git a/lib/CodeGen/MachineOperand.cpp b/lib/CodeGen/MachineOperand.cpp
index 8eccfb8..8b19501 100644
--- a/lib/CodeGen/MachineOperand.cpp
+++ b/lib/CodeGen/MachineOperand.cpp
@@ -979,7 +979,8 @@
     return false;
 
   return isDereferenceableAndAlignedPointer(
-      BasePtr, 1, APInt(DL.getPointerSizeInBits(), Offset + Size), DL);
+      BasePtr, Align::None(), APInt(DL.getPointerSizeInBits(), Offset + Size),
+      DL);
 }
 
 /// getConstantPool - Return a MachinePointerInfo record that refers to the
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 8d4b0dc..c15fb27 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1059,9 +1059,9 @@
 
   // If we can unconditionally load from this address, replace with a
   // load/select idiom. TODO: use DT for context sensitive query
-  if (isDereferenceableAndAlignedPointer(LoadPtr, II.getType(), Alignment,
-                                         II.getModule()->getDataLayout(),
-                                         &II, nullptr)) {
+  if (isDereferenceableAndAlignedPointer(
+          LoadPtr, II.getType(), MaybeAlign(Alignment),
+          II.getModule()->getDataLayout(), &II, nullptr)) {
     Value *LI = Builder.CreateAlignedLoad(II.getType(), LoadPtr, Alignment,
                                          "unmaskedload");
     return Builder.CreateSelect(II.getArgOperand(2), LI, II.getArgOperand(3));
diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 4c5e1cc..3e035f4 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -175,7 +175,7 @@
   uint64_t AllocaSize = DL.getTypeStoreSize(AI->getAllocatedType());
   if (!AllocaSize)
     return false;
-  return isDereferenceableAndAlignedPointer(V, AI->getAlignment(),
+  return isDereferenceableAndAlignedPointer(V, Align(AI->getAlignment()),
                                             APInt(64, AllocaSize), DL);
 }
 
@@ -1020,11 +1020,11 @@
     //
     if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
       // load (select (Cond, &V1, &V2))  --> select(Cond, load &V1, load &V2).
-      unsigned Align = LI.getAlignment();
-      if (isSafeToLoadUnconditionally(SI->getOperand(1), LI.getType(), Align,
-                                      DL, SI) &&
-          isSafeToLoadUnconditionally(SI->getOperand(2), LI.getType(), Align,
-                                      DL, SI)) {
+      const MaybeAlign Alignment(LI.getAlignment());
+      if (isSafeToLoadUnconditionally(SI->getOperand(1), LI.getType(),
+                                      Alignment, DL, SI) &&
+          isSafeToLoadUnconditionally(SI->getOperand(2), LI.getType(),
+                                      Alignment, DL, SI)) {
         LoadInst *V1 =
             Builder.CreateLoad(LI.getType(), SI->getOperand(1),
                                SI->getOperand(1)->getName() + ".val");
@@ -1032,9 +1032,9 @@
             Builder.CreateLoad(LI.getType(), SI->getOperand(2),
                                SI->getOperand(2)->getName() + ".val");
         assert(LI.isUnordered() && "implied by above");
-        V1->setAlignment(MaybeAlign(Align));
+        V1->setAlignment(Alignment);
         V1->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-        V2->setAlignment(MaybeAlign(Align));
+        V2->setAlignment(Alignment);
         V2->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
         return SelectInst::Create(SI->getCondition(), V1, V2);
       }
diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 262d64f..6ce4831 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -2033,7 +2033,8 @@
         if (!DereferenceableInPH) {
           DereferenceableInPH = isDereferenceableAndAlignedPointer(
               Store->getPointerOperand(), Store->getValueOperand()->getType(),
-              Store->getAlignment(), MDL, Preheader->getTerminator(), DT);
+              MaybeAlign(Store->getAlignment()), MDL,
+              Preheader->getTerminator(), DT);
         }
       } else
         return false; // Not a load or store.
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index 4b81683..74b8ff9 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -1199,7 +1199,7 @@
   // TODO: Allow recursive phi users.
   // TODO: Allow stores.
   BasicBlock *BB = PN.getParent();
-  unsigned MaxAlign = 0;
+  MaybeAlign MaxAlign;
   uint64_t APWidth = DL.getIndexTypeSizeInBits(PN.getType());
   APInt MaxSize(APWidth, 0);
   bool HaveLoad = false;
@@ -1221,7 +1221,7 @@
         return false;
 
     uint64_t Size = DL.getTypeStoreSize(LI->getType());
-    MaxAlign = std::max(MaxAlign, LI->getAlignment());
+    MaxAlign = std::max(MaxAlign, MaybeAlign(LI->getAlignment()));
     MaxSize = MaxSize.ult(Size) ? APInt(APWidth, Size) : MaxSize;
     HaveLoad = true;
   }
@@ -1340,11 +1340,11 @@
     // Both operands to the select need to be dereferenceable, either
     // absolutely (e.g. allocas) or at this point because we can see other
     // accesses to it.
-    if (!isSafeToLoadUnconditionally(TValue, LI->getType(), LI->getAlignment(),
-                                     DL, LI))
+    if (!isSafeToLoadUnconditionally(TValue, LI->getType(),
+                                     MaybeAlign(LI->getAlignment()), DL, LI))
       return false;
-    if (!isSafeToLoadUnconditionally(FValue, LI->getType(), LI->getAlignment(),
-                                     DL, LI))
+    if (!isSafeToLoadUnconditionally(FValue, LI->getType(),
+                                     MaybeAlign(LI->getAlignment()), DL, LI))
       return false;
   }
 
diff --git a/lib/Transforms/Scalar/TailRecursionElimination.cpp b/lib/Transforms/Scalar/TailRecursionElimination.cpp
index f0b7907..b27a36b 100644
--- a/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -341,7 +341,7 @@
       const DataLayout &DL = L->getModule()->getDataLayout();
       if (isModSet(AA->getModRefInfo(CI, MemoryLocation::get(L))) ||
           !isSafeToLoadUnconditionally(L->getPointerOperand(), L->getType(),
-                                       L->getAlignment(), DL, L))
+                                       MaybeAlign(L->getAlignment()), DL, L))
         return false;
     }
   }
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 361b559..0324993 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -177,7 +177,8 @@
   if (!isOnlyUsedInComparisonWithZero(CI))
     return false;
 
-  if (!isDereferenceableAndAlignedPointer(Str, 1, APInt(64, Len), DL))
+  if (!isDereferenceableAndAlignedPointer(Str, Align::None(), APInt(64, Len),
+                                          DL))
     return false;
 
   if (CI->getFunction()->hasFnAttribute(Attribute::SanitizeMemory))