diff --git a/llvm/lib/Target/BPF/BPFISelLowering.h b/llvm/lib/Target/BPF/BPFISelLowering.h
--- a/llvm/lib/Target/BPF/BPFISelLowering.h
+++ b/llvm/lib/Target/BPF/BPFISelLowering.h
@@ -99,6 +99,9 @@
                       const SmallVectorImpl<SDValue> &OutVals, const SDLoc &DL,
                       SelectionDAG &DAG) const override;
 
+  void ReplaceNodeResults(SDNode *N, SmallVectorImpl<SDValue> &Results,
+                          SelectionDAG &DAG) const override;
+
   EVT getOptimalMemOpType(const MemOp &Op,
                           const AttributeList &FuncAttributes) const override {
     return Op.size() >= 8 ? MVT::i64 : MVT::i32;
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp b/llvm/lib/Target/BPF/BPFISelLowering.cpp
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -78,6 +78,24 @@
   setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
   setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
 
+  // Set unsupported atomic operations as Custom so
+  // we can emit better error messages than fatal error
+  // from selectiondag.
+  for (auto VT : {MVT::i8, MVT::i16, MVT::i32}) {
+    if (VT == MVT::i32) {
+      if (STI.getHasAlu32())
+        continue;
+    } else {
+      setOperationAction(ISD::ATOMIC_LOAD_ADD, VT, Custom);
+    }
+
+    setOperationAction(ISD::ATOMIC_LOAD_AND, VT, Custom);
+    setOperationAction(ISD::ATOMIC_LOAD_OR, VT, Custom);
+    setOperationAction(ISD::ATOMIC_LOAD_XOR, VT, Custom);
+    setOperationAction(ISD::ATOMIC_SWAP, VT, Custom);
+    setOperationAction(ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS, VT, Custom);
+  }
+
   for (auto VT : { MVT::i32, MVT::i64 }) {
     if (VT == MVT::i32 && !STI.getHasAlu32())
       continue;
@@ -218,6 +236,30 @@
   return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
 }
 
+void BPFTargetLowering::ReplaceNodeResults(
+  SDNode *N, SmallVectorImpl<SDValue> &Results, SelectionDAG &DAG) const {
+  const char *err_msg;
+  uint32_t Opcode = N->getOpcode();
+  switch (Opcode) {
+  default:
+    report_fatal_error("Unhandled custom legalization");
+  case ISD::ATOMIC_LOAD_ADD:
+  case ISD::ATOMIC_LOAD_AND:
+  case ISD::ATOMIC_LOAD_OR:
+  case ISD::ATOMIC_LOAD_XOR:
+  case ISD::ATOMIC_SWAP:
+  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
+    if (HasAlu32 || Opcode == ISD::ATOMIC_LOAD_ADD)
+      err_msg = "Unsupported atomic operations, please use 32/64 bit version";
+    else
+      err_msg = "Unsupported atomic operations, please use 64 bit version";
+    break;
+  }
+
+  SDLoc DL(N);
+  fail(DL, DAG, err_msg);
+}
+
 SDValue BPFTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   switch (Op.getOpcode()) {
   case ISD::BR_CC: