diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -509,8 +509,7 @@
       return;
     }
     DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, SrcLOI->NumSignBits);
-    DestLOI.Known.Zero &= SrcLOI->Known.Zero;
-    DestLOI.Known.One &= SrcLOI->Known.One;
+    DestLOI.Known = KnownBits::commonBits(DestLOI.Known, SrcLOI->Known);
   }
 }
 
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
@@ -1016,10 +1016,8 @@
                              Depth + 1))
       return true;
 
-    if (!!DemandedVecElts) {
-      Known.One &= KnownVec.One;
-      Known.Zero &= KnownVec.Zero;
-    }
+    if (!!DemandedVecElts)
+      Known = KnownBits::commonBits(Known, KnownVec);
 
     return false;
   }
@@ -1044,14 +1042,10 @@
 
     Known.Zero.setAllBits();
     Known.One.setAllBits();
-    if (!!DemandedSubElts) {
-      Known.One &= KnownSub.One;
-      Known.Zero &= KnownSub.Zero;
-    }
-    if (!!DemandedSrcElts) {
-      Known.One &= KnownSrc.One;
-      Known.Zero &= KnownSrc.Zero;
-    }
+    if (!!DemandedSubElts)
+      Known = KnownBits::commonBits(Known, KnownSub);
+    if (!!DemandedSrcElts)
+      Known = KnownBits::commonBits(Known, KnownSrc);
 
     // Attempt to avoid multi-use src if we don't need anything from it.
     if (!DemandedBits.isAllOnesValue() || !DemandedSubElts.isAllOnesValue() ||
@@ -1108,10 +1102,8 @@
                                Known2, TLO, Depth + 1))
         return true;
       // Known bits are shared by every demanded subvector element.
-      if (!!DemandedSubElts) {
-        Known.One &= Known2.One;
-        Known.Zero &= Known2.Zero;
-      }
+      if (!!DemandedSubElts)
+        Known = KnownBits::commonBits(Known, Known2);
     }
     break;
   }
@@ -1149,15 +1141,13 @@
         if (SimplifyDemandedBits(Op0, DemandedBits, DemandedLHS, Known2, TLO,
                                  Depth + 1))
           return true;
-        Known.One &= Known2.One;
-        Known.Zero &= Known2.Zero;
+        Known = KnownBits::commonBits(Known, Known2);
       }
       if (!!DemandedRHS) {
         if (SimplifyDemandedBits(Op1, DemandedBits, DemandedRHS, Known2, TLO,
                                  Depth + 1))
           return true;
-        Known.One &= Known2.One;
-        Known.Zero &= Known2.Zero;
+        Known = KnownBits::commonBits(Known, Known2);
       }
 
       // Attempt to avoid multi-use ops if we don't need anything from them.
@@ -1384,8 +1374,7 @@
       return true;
 
     // Only known if known in both the LHS and RHS.
-    Known.One &= Known2.One;
-    Known.Zero &= Known2.Zero;
+    Known = KnownBits::commonBits(Known, Known2);
     break;
   case ISD::SELECT_CC:
     if (SimplifyDemandedBits(Op.getOperand(3), DemandedBits, Known, TLO,
@@ -1402,8 +1391,7 @@
       return true;
 
     // Only known if known in both the LHS and RHS.
-    Known.One &= Known2.One;
-    Known.Zero &= Known2.Zero;
+    Known = KnownBits::commonBits(Known, Known2);
     break;
   case ISD::SETCC: {
     SDValue Op0 = Op.getOperand(0);