diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -1815,9 +1815,17 @@
   bool areNonVolatileConsecutiveLoads(LoadSDNode *LD, LoadSDNode *Base,
                                       unsigned Bytes, int Dist) const;
 
-  /// Infer alignment of a load / store address. Return 0 if
-  /// it cannot be inferred.
-  unsigned InferPtrAlignment(SDValue Ptr) const;
+  /// Infer alignment of a load / store address. Return None if it cannot be
+  /// inferred.
+  MaybeAlign InferPtrAlign(SDValue Ptr) const;
+
+  LLVM_ATTRIBUTE_DEPRECATED(inline unsigned InferPtrAlignment(SDValue Ptr)
+                                const,
+                            "Use InferPtrAlign instead") {
+    if (auto A = InferPtrAlign(Ptr))
+      return A->value();
+    return 0;
+  }
 
   /// Compute the VTs needed for the low/hi parts of a type
   /// which is split (or expanded) into two not necessarily identical pieces.
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -14633,11 +14633,12 @@
 
   // Try to infer better alignment information than the load already has.
   if (OptLevel != CodeGenOpt::None && LD->isUnindexed() && !LD->isAtomic()) {
-    if (unsigned Align = DAG.InferPtrAlignment(Ptr)) {
-      if (Align > LD->getAlignment() && LD->getSrcValueOffset() % Align == 0) {
+    if (MaybeAlign Alignment = DAG.InferPtrAlign(Ptr)) {
+      if (*Alignment > LD->getAlign() &&
+          isAligned(*Alignment, LD->getSrcValueOffset())) {
         SDValue NewLoad = DAG.getExtLoad(
             LD->getExtensionType(), SDLoc(N), LD->getValueType(0), Chain, Ptr,
-            LD->getPointerInfo(), LD->getMemoryVT(), Align,
+            LD->getPointerInfo(), LD->getMemoryVT(), *Alignment,
             LD->getMemOperand()->getFlags(), LD->getAAInfo());
         // NewLoad will always be N as we are only refining the alignment
         assert(NewLoad.getNode() == N);
@@ -16699,11 +16700,12 @@
 
   // Try to infer better alignment information than the store already has.
   if (OptLevel != CodeGenOpt::None && ST->isUnindexed() && !ST->isAtomic()) {
-    if (unsigned Align = DAG.InferPtrAlignment(Ptr)) {
-      if (Align > ST->getAlignment() && ST->getSrcValueOffset() % Align == 0) {
+    if (MaybeAlign Alignment = DAG.InferPtrAlign(Ptr)) {
+      if (*Alignment > ST->getAlign() &&
+          isAligned(*Alignment, ST->getSrcValueOffset())) {
         SDValue NewStore =
             DAG.getTruncStore(Chain, SDLoc(N), Value, Ptr, ST->getPointerInfo(),
-                              ST->getMemoryVT(), Align,
+                              ST->getMemoryVT(), *Alignment,
                               ST->getMemOperand()->getFlags(), ST->getAAInfo());
         // NewStore will always be N as we are only refining the alignment
         assert(NewStore.getNode() == N);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5916,7 +5916,7 @@
   FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Dst);
   if (FI && !MFI.isFixedObjectIndex(FI->getIndex()))
     DstAlignCanChange = true;
-  MaybeAlign SrcAlign(DAG.InferPtrAlignment(Src));
+  MaybeAlign SrcAlign = DAG.InferPtrAlign(Src);
   if (!SrcAlign || Alignment > *SrcAlign)
     SrcAlign = Alignment;
   assert(SrcAlign && "SrcAlign must be set");
@@ -6101,7 +6101,7 @@
   FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Dst);
   if (FI && !MFI.isFixedObjectIndex(FI->getIndex()))
     DstAlignCanChange = true;
-  MaybeAlign SrcAlign(DAG.InferPtrAlignment(Src));
+  MaybeAlign SrcAlign = DAG.InferPtrAlign(Src);
   if (!SrcAlign || Alignment > *SrcAlign)
     SrcAlign = Alignment;
   assert(SrcAlign && "SrcAlign must be set");
@@ -9418,9 +9418,9 @@
   return false;
 }
 
-/// InferPtrAlignment - Infer alignment of a load / store address. Return 0 if
-/// it cannot be inferred.
-unsigned SelectionDAG::InferPtrAlignment(SDValue Ptr) const {
+/// InferPtrAlignment - Infer alignment of a load / store address. Return None
+/// if it cannot be inferred.
+MaybeAlign SelectionDAG::InferPtrAlign(SDValue Ptr) const {
   // If this is a GlobalAddress + cst, return the alignment.
   const GlobalValue *GV = nullptr;
   int64_t GVOffset = 0;
@@ -9429,9 +9429,8 @@
     KnownBits Known(PtrWidth);
     llvm::computeKnownBits(GV, Known, getDataLayout());
     unsigned AlignBits = Known.countMinTrailingZeros();
-    unsigned Align = AlignBits ? 1 << std::min(31U, AlignBits) : 0;
-    if (Align)
-      return MinAlign(Align, GVOffset);
+    if (AlignBits)
+      return commonAlignment(Align(1 << std::min(31U, AlignBits)), GVOffset);
   }
 
   // If this is a direct reference to a stack slot, use information about the
@@ -9449,12 +9448,10 @@
 
   if (FrameIdx != INT_MIN) {
     const MachineFrameInfo &MFI = getMachineFunction().getFrameInfo();
-    unsigned FIInfoAlign = MinAlign(MFI.getObjectAlignment(FrameIdx),
-                                    FrameOffset);
-    return FIInfoAlign;
+    return commonAlignment(MFI.getObjectAlign(FrameIdx), FrameOffset);
   }
 
-  return 0;
+  return None;
 }
 
 /// GetSplitDestVTs - Compute the VTs needed for the low/hi parts of a type
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7333,10 +7333,10 @@
   SDValue Src = getValue(I.getArgOperand(1));
   SDValue Size = getValue(I.getArgOperand(2));
 
-  unsigned DstAlign = DAG.InferPtrAlignment(Dst);
-  unsigned SrcAlign = DAG.InferPtrAlignment(Src);
+  Align DstAlign = DAG.InferPtrAlign(Dst).valueOrOne();
+  Align SrcAlign = DAG.InferPtrAlign(Src).valueOrOne();
   // DAG::getMemcpy needs Alignment to be defined.
-  Align Alignment = assumeAligned(std::min(DstAlign, SrcAlign));
+  Align Alignment = std::min(DstAlign, SrcAlign);
 
   bool isVol = false;
   SDLoc sdl = getCurSDLoc();
@@ -9492,16 +9492,13 @@
                   "object size\n");
     return;
   }
-  unsigned RequiredAlignment = AI->getAlignment();
-  if (!RequiredAlignment) {
-    RequiredAlignment = FuncInfo.MF->getDataLayout().getABITypeAlignment(
-        AI->getAllocatedType());
-  }
-  if (MFI.getObjectAlignment(FixedIndex) < RequiredAlignment) {
+  Align RequiredAlignment = AI->getAlign().getValueOr(
+      FuncInfo.MF->getDataLayout().getABITypeAlign(AI->getAllocatedType()));
+  if (MFI.getObjectAlign(FixedIndex) < RequiredAlignment) {
     LLVM_DEBUG(dbgs() << "  argument copy elision failed: alignment of alloca "
                          "greater than stack argument alignment ("
-                      << RequiredAlignment << " vs "
-                      << MFI.getObjectAlignment(FixedIndex) << ")\n");
+                      << RequiredAlignment.value() << " vs "
+                      << MFI.getObjectAlign(FixedIndex).value() << ")\n");
     return;
   }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2762,9 +2762,9 @@
                                                    unsigned Depth) const {
   assert(isa<FrameIndexSDNode>(Op) && "expected FrameIndex");
 
-  if (unsigned Align = DAG.InferPtrAlignment(Op)) {
+  if (MaybeAlign Alignment = DAG.InferPtrAlign(Op)) {
     // The low bits are known zero if the pointer is aligned.
-    Known.Zero.setLowBits(Log2_32(Align));
+    Known.Zero.setLowBits(Log2(*Alignment));
   }
 }
 
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -2272,9 +2272,9 @@
         for (i = 0, j = RegBegin; j < RegEnd; i++, j++) {
           SDValue Const = DAG.getConstant(4*i, dl, MVT::i32);
           SDValue AddArg = DAG.getNode(ISD::ADD, dl, PtrVT, Arg, Const);
-          SDValue Load = DAG.getLoad(PtrVT, dl, Chain, AddArg,
-                                     MachinePointerInfo(),
-                                     DAG.InferPtrAlignment(AddArg));
+          SDValue Load =
+              DAG.getLoad(PtrVT, dl, Chain, AddArg, MachinePointerInfo(),
+                          DAG.InferPtrAlign(AddArg));
           MemOpChains.push_back(Load.getValue(1));
           RegsToPass.push_back(std::make_pair(j, Load));
         }
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -8137,7 +8137,7 @@
     SDValue Chain = LD->getChain();
     // Make sure the stack object alignment is at least 16 or 32.
     MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
-    if (DAG.InferPtrAlignment(Ptr) < RequiredAlign) {
+    if (DAG.InferPtrAlign(Ptr) < RequiredAlign) {
       if (MFI.isFixedObjectIndex(FI)) {
         // Can't change the alignment. FIXME: It's possible to compute
         // the exact stack offset and reference FI + adjust offset instead.