Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -300,12 +300,13 @@
                             TI->getType());
   }
 
-  // Only handle binary operators with one-use here. As with the cast case
-  // above, it may be possible to relax the one-use constraint, but that needs
-  // be examined carefully since it may not reduce the total number of
-  // instructions.
-  BinaryOperator *BO = dyn_cast<BinaryOperator>(TI);
-  if (!BO || !TI->hasOneUse() || !FI->hasOneUse())
+  // Only handle binary operators (including two-operand getelementptr) with
+  // one-use here. As with the cast case above, it may be possible to relax the
+  // one-use constraint, but that needs be examined carefully since it may not
+  // reduce the total number of instructions.
+  if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 ||
+      (!isa<BinaryOperator>(TI) && !isa<GetElementPtrInst>(TI)) ||
+      !TI->hasOneUse() || !FI->hasOneUse())
     return nullptr;
 
   // Figure out if the operations have any operands in common.
@@ -342,7 +343,18 @@
                                       SI.getName() + ".v", &SI);
   Value *Op0 = MatchIsOpZero ? MatchOp : NewSI;
   Value *Op1 = MatchIsOpZero ? NewSI : MatchOp;
-  return BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
+    return BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
+  }
+  if (GetElementPtrInst *TGEP = dyn_cast<GetElementPtrInst>(TI)) {
+    GetElementPtrInst *FGEP = dyn_cast<GetElementPtrInst>(FI);
+    Type *ElementType = TGEP->getResultElementType();
+    return TGEP->isInBounds() && FGEP->isInBounds()
+               ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1})
+               : GetElementPtrInst::Create(ElementType, Op0, {Op1});
+  }
+  llvm_unreachable("Expected BinaryOperator or GEP");
+  return nullptr;
 }
 
 static bool isSelect01(const APInt &C1I, const APInt &C2I) {
Index: test/Transforms/InstCombine/select-gep.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/select-gep.ll
@@ -0,0 +1,125 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; CHECK-LABEL: @test1a
+; CHECK: [[CMP:%.*]] = icmp ugt i32* %p, %q
+; CHECK: [[SEL:%.*]] = select i1 [[CMP]], i32* %p, i32* %q
+; CHECK: [[GEP:%.*]] = getelementptr i32, i32* [[SEL]], i64 4
+; CHECK: ret i32* [[GEP]]
+define i32* @test1a(i32* %p, i32* %q) {
+  %gep1 = getelementptr i32, i32* %p, i64 4
+  %gep2 = getelementptr i32, i32* %q, i64 4
+  %cmp = icmp ugt i32* %p, %q
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test1b
+; CHECK: [[CMP:%.*]] = icmp ugt i32* %p, %q
+; CHECK: [[SEL:%.*]] = select i1 [[CMP]], i32* %p, i32* %q
+; CHECK: [[GEP:%.*]] = getelementptr i32, i32* [[SEL]], i64 4
+; CHECK: ret i32* [[GEP]]
+define i32* @test1b(i32* %p, i32* %q) {
+  %gep1 = getelementptr inbounds i32, i32* %p, i64 4
+  %gep2 = getelementptr i32, i32* %q, i64 4
+  %cmp = icmp ugt i32* %p, %q
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test1c
+; CHECK: [[CMP:%.*]] = icmp ugt i32* %p, %q
+; CHECK: [[SEL:%.*]] = select i1 [[CMP]], i32* %p, i32* %q
+; CHECK: [[GEP:%.*]] = getelementptr i32, i32* [[SEL]], i64 4
+; CHECK: ret i32* [[GEP]]
+define i32* @test1c(i32* %p, i32* %q) {
+  %gep1 = getelementptr i32, i32* %p, i64 4
+  %gep2 = getelementptr inbounds i32, i32* %q, i64 4
+  %cmp = icmp ugt i32* %p, %q
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test1d
+; CHECK: [[CMP:%.*]] = icmp ugt i32* %p, %q
+; CHECK: [[SEL:%.*]] = select i1 [[CMP]], i32* %p, i32* %q
+; CHECK: [[GEP:%.*]] = getelementptr inbounds i32, i32* [[SEL]], i64 4
+; CHECK: ret i32* [[GEP]]
+define i32* @test1d(i32* %p, i32* %q) {
+  %gep1 = getelementptr inbounds i32, i32* %p, i64 4
+  %gep2 = getelementptr inbounds i32, i32* %q, i64 4
+  %cmp = icmp ugt i32* %p, %q
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test2
+; CHECK: [[CMP:%.*]] = icmp ugt i64 %x, %y
+; CHECK: [[SEL:%.*]] = select i1 [[CMP]], i64 %x, i64 %y
+; CHECK: [[GEP:%.*]] = getelementptr inbounds i32, i32* %p, i64 [[SEL]]
+; CHECK: ret i32* [[GEP]]
+define i32* @test2(i32* %p, i64 %x, i64 %y) {
+  %gep1 = getelementptr inbounds i32, i32* %p, i64 %x
+  %gep2 = getelementptr inbounds i32, i32* %p, i64 %y
+  %cmp = icmp ugt i64 %x, %y
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; Three (or more) operand GEPs are currently expected to not be optimised,
+; though they could be in principle.
+; CHECK-LABEL: @test3a
+; CHECK: %gep1 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 2, i64 %x
+; CHECK: %gep2 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 2, i64 %y
+; CHECK: %cmp = icmp ugt i64 %x, %y
+; CHECK: %select = select i1 %cmp, i32* %gep1, i32* %gep2
+; CHECK: ret i32* %select
+define i32* @test3a([4 x i32]* %p, i64 %x, i64 %y) {
+  %gep1 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 2, i64 %x
+  %gep2 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 2, i64 %y
+  %cmp = icmp ugt i64 %x, %y
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test3b
+; CHECK: %gep1 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 %x, i64 2
+; CHECK: %gep2 = getelementptr inbounds i32, i32* %q, i64 %x
+; CHECK: %cmp = icmp ugt i64 %x, %y
+; CHECK: %select = select i1 %cmp, i32* %gep1, i32* %gep2
+; CHECK: ret i32* %select
+define i32* @test3b([4 x i32]* %p, i32* %q, i64 %x, i64 %y) {
+  %gep1 = getelementptr inbounds [4 x i32], [4 x i32]* %p, i64 %x, i64 2
+  %gep2 = getelementptr inbounds i32, i32* %q, i64 %x
+  %cmp = icmp ugt i64 %x, %y
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; CHECK-LABEL: @test3c
+; CHECK: %gep1 = getelementptr inbounds i32, i32* %p, i64 %x
+; CHECK: %gep2 = getelementptr inbounds [4 x i32], [4 x i32]* %q, i64 %x, i64 2
+; CHECK: %cmp = icmp ugt i64 %x, %y
+; CHECK: %select = select i1 %cmp, i32* %gep1, i32* %gep2
+; CHECK: ret i32* %select
+define i32* @test3c(i32* %p, [4 x i32]* %q, i64 %x, i64 %y) {
+  %gep1 = getelementptr inbounds i32, i32* %p, i64 %x
+  %gep2 = getelementptr inbounds [4 x i32], [4 x i32]* %q, i64 %x, i64 2
+  %cmp = icmp ugt i64 %x, %y
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}
+
+; Shouldn't be optimised as it would mean introducing an extra select
+; CHECK-LABEL: @test4
+; CHECK: %gep1 = getelementptr inbounds i32, i32* %p, i64 %x
+; CHECK: %gep2 = getelementptr inbounds i32, i32* %q, i64 %y
+; CHECK: %cmp = icmp ugt i64 %x, %y
+; CHECK: %select = select i1 %cmp, i32* %gep1, i32* %gep2
+; CHECK: ret i32* %select
+define i32* @test4(i32* %p, i32* %q, i64 %x, i64 %y) {
+  %gep1 = getelementptr inbounds i32, i32* %p, i64 %x
+  %gep2 = getelementptr inbounds i32, i32* %q, i64 %y
+  %cmp = icmp ugt i64 %x, %y
+  %select = select i1 %cmp, i32* %gep1, i32* %gep2
+  ret i32* %select
+}