Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9945,6 +9945,46 @@
   return SDValue();
 }
 
+/// Fold
+///   (sext (select c, load x, load y)) -> (select c, sextload x, sextload y)
+///   (zext (select c, load x, load y)) -> (select c, zextload x, zextload y)
+///   (aext (select c, load x, load y)) -> (select c, aextload x, extload y)
+/// This function is called by the DAGCombiner when visiting sext/zext/aext
+/// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND).
+static SDValue tryToFoldExtendSelectLoad(SDNode *N, const TargetLowering &TLI,
+                                         SelectionDAG &DAG) {
+  unsigned Opcode = N->getOpcode();
+  SDValue N0 = N->getOperand(0);
+  EVT VT = N->getValueType(0);
+  SDLoc DL(N);
+
+  assert((Opcode == ISD::SIGN_EXTEND || Opcode == ISD::ZERO_EXTEND ||
+          Opcode == ISD::ANY_EXTEND) && "Expected EXTEND dag node in input!");
+
+  if (N0->getOpcode() != ISD::SELECT || !N0.hasOneUse())
+    return SDValue();
+
+  SDValue Op1 = N0->getOperand(1);
+  SDValue Op2 = N0->getOperand(2);
+  if (!isa<LoadSDNode>(Op1) || !isa<LoadSDNode>(Op2) ||
+      !Op1.hasOneUse() || !Op2.hasOneUse())
+    return SDValue();
+
+  auto ExtLoadOpcode = ISD::EXTLOAD;
+  if (Opcode == ISD::SIGN_EXTEND)
+    ExtLoadOpcode = ISD::SEXTLOAD;
+  else if (Opcode == ISD::ZERO_EXTEND)
+    ExtLoadOpcode = ISD::ZEXTLOAD;
+
+  LoadSDNode *Load1 = cast<LoadSDNode>(Op1);
+  if (!TLI.isLoadExtLegal(ExtLoadOpcode, VT, Load1->getMemoryVT()))
+    return SDValue();
+
+  SDValue Ext1 = DAG.getNode(Opcode, DL, VT, Op1);
+  SDValue Ext2 = DAG.getNode(Opcode, DL, VT, Op2);
+  return DAG.getSelect(DL, VT, N0->getOperand(0), Ext1, Ext2);
+}
+
 /// Try to fold a sext/zext/aext dag node into a ConstantSDNode or
 /// a build_vector of constants.
 /// This function is called by the DAGCombiner when visiting sext/zext/aext
@@ -10729,6 +10769,9 @@
     return DAG.getNode(ISD::ADD, DL, VT, Zext, DAG.getAllOnesConstant(DL, VT));
   }
 
+  if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
+    return Res;
+
   return SDValue();
 }
 
@@ -11041,6 +11084,9 @@
   if (SDValue NewCtPop = widenCtPop(N, DAG))
     return NewCtPop;
 
+  if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
+    return Res;
+
   return SDValue();
 }
 
@@ -11193,6 +11239,9 @@
   if (SDValue NewCtPop = widenCtPop(N, DAG))
     return NewCtPop;
 
+  if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
+    return Res;
+
   return SDValue();
 }
 
Index: llvm/test/CodeGen/X86/select-ext.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/select-ext.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
+
+; (zext(select c, load1, load2)) -> (select c, zextload1, zextload2)
+
+; CHECK-LABEL: foo
+; CHECK:        movzbl  (%rdi), %ecx
+; CHECK-NEXT:   movzbl  1(%rdi), %eax
+; CHECK-NEXT:   testl   %esi, %esi
+; CHECK-NEXT:   cmoveq  %rcx, %rax
+; CHECK-NEXT:   retq
+
+define i64 @foo(i8* %p, i1 zeroext %c) {
+  %ld1 = load volatile i8, i8* %p
+  %arrayidx1 = getelementptr inbounds i8, i8* %p, i64 1
+  %ld2 = load volatile i8, i8* %arrayidx1
+  %cond.v = select i1 %c, i8 %ld2, i8 %ld1
+  %cond = zext i8 %cond.v to i64
+  ret i64 %cond
+}
+