Index: include/llvm/CodeGen/ISDOpcodes.h
===================================================================
--- include/llvm/CodeGen/ISDOpcodes.h
+++ include/llvm/CodeGen/ISDOpcodes.h
@@ -49,6 +49,12 @@
     /// operators are independent of each other.
     TokenFactor,
 
+    /// This node records if a register contains a value that has been masked
+    /// by an and with constant.  This node takes two operands. The first is
+    /// the node that has already been masked by an and operation, and the
+    /// second is the constant mask that was used.
+    AssertAnd,
+
     /// AssertSext, AssertZext - These nodes record if a register contains a
     /// value that has already been zero or sign extended from a narrower type.
     /// These nodes take two operands.  The first is the node that has already
Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2034,6 +2034,7 @@
     KnownOne = cast<ConstantSDNode>(Op)->getAPIntValue();
     KnownZero = ~KnownOne;
     break;
+  case ISD::AssertAnd:
   case ISD::AND:
     // If either the LHS or the RHS are Zero, the result is zero.
     computeKnownBits(Op.getOperand(1), KnownZero, KnownOne, Depth+1);
@@ -2537,6 +2538,7 @@
       return Tmp - C->getZExtValue();
     }
     break;
+  case ISD::AssertAnd:
   case ISD::AND:
   case ISD::OR:
   case ISD::XOR:    // NOT is handled here.
@@ -3452,6 +3454,13 @@
            isa<ConstantSDNode>(N2) && "Invalid FP_ROUND!");
     if (N1.getValueType() == VT) return N1;  // noop conversion.
     break;
+  case ISD::AssertAnd: {
+    ConstantSDNode *C2 = cast<ConstantSDNode>(N2);
+    assert(N1.getValueType() == N2.getValueType() &&
+           N1.getValueType() == VT && "Binary operator types must match!");
+    if (C2->isAllOnesValue()) return N1; // noop mask.
+    break;
+  }
   case ISD::AssertSext:
   case ISD::AssertZext: {
     EVT EVT = cast<VTSDNode>(N2)->getVT();
Index: lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -76,6 +76,7 @@
   case ISD::MDNODE_SDNODE:              return "MDNode";
   case ISD::EntryToken:                 return "EntryToken";
   case ISD::TokenFactor:                return "TokenFactor";
+  case ISD::AssertAnd:                  return "AssertAnd";
   case ISD::AssertSext:                 return "AssertSext";
   case ISD::AssertZext:                 return "AssertZext";
 
Index: lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2575,6 +2575,7 @@
   case ISD::LIFETIME_END:
     NodeToMatch->setNodeId(-1); // Mark selected.
     return nullptr;
+  case ISD::AssertAnd:
   case ISD::AssertSext:
   case ISD::AssertZext:
     CurDAG->ReplaceAllUsesOfValueWith(SDValue(NodeToMatch, 0),