diff --git a/llvm/lib/Target/BPF/BPFRegisterInfo.cpp b/llvm/lib/Target/BPF/BPFRegisterInfo.cpp
index 71846e3e92c9..7925bee9c587 100644
--- a/llvm/lib/Target/BPF/BPFRegisterInfo.cpp
+++ b/llvm/lib/Target/BPF/BPFRegisterInfo.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/IR/DiagnosticInfo.h"
 
 #define GET_REGINFO_TARGET_DESC
 #include "BPFGenRegisterInfo.inc"
@@ -41,6 +42,18 @@ BitVector BPFRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   return Reserved;
 }
 
+static void WarnSize(int Offset, MachineFunction &MF, DebugLoc& DL)
+{
+  if (Offset <= -512) {
+      auto F = MF.getFunction();
+      DiagnosticInfoUnsupported DiagStackSize(*F,
+          "Looks like the BPF stack limit of 512 bytes is exceeded. "
+          "Please move large on stack variables into BPF per-cpu array map.\n",
+          DL);
+      F->getContext().diagnose(DiagStackSize);
+  }
+}
+
 void BPFRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
                                           int SPAdj, unsigned FIOperandNum,
                                           RegScavenger *RS) const {
@@ -48,9 +61,18 @@ void BPFRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 
   unsigned i = 0;
   MachineInstr &MI = *II;
-  MachineFunction &MF = *MI.getParent()->getParent();
+  MachineBasicBlock &MBB = *MI.getParent();
+  MachineFunction &MF = *MBB.getParent();
   DebugLoc DL = MI.getDebugLoc();
 
+  if (!DL)
+    /* try harder to get some debug loc */
+    for (auto &I : MBB)
+      if (I.getDebugLoc()) {
+        DL = I.getDebugLoc();
+        break;
+      }
+
   while (!MI.getOperand(i).isFI()) {
     ++i;
     assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
@@ -59,11 +81,11 @@ void BPFRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   unsigned FrameReg = getFrameRegister(MF);
   int FrameIndex = MI.getOperand(i).getIndex();
   const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
-  MachineBasicBlock &MBB = *MI.getParent();
 
   if (MI.getOpcode() == BPF::MOV_rr) {
     int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex);
 
+    WarnSize(Offset, MF, DL);
     MI.getOperand(i).ChangeToRegister(FrameReg, false);
     unsigned reg = MI.getOperand(i - 1).getReg();
     BuildMI(MBB, ++II, DL, TII.get(BPF::ADD_ri), reg)
@@ -78,6 +100,8 @@ void BPFRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   if (!isInt<32>(Offset))
     llvm_unreachable("bug in frame offset");
 
+  WarnSize(Offset, MF, DL);
+
   if (MI.getOpcode() == BPF::FI_ri) {
     // architecture does not really support FI_ri, replace it with
     //    MOV_rr <target_reg>, frame_reg
diff --git a/llvm/test/CodeGen/BPF/warn-stack.ll b/llvm/test/CodeGen/BPF/warn-stack.ll
new file mode 100644
index 000000000000..b7992960b73e
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/warn-stack.ll
@@ -0,0 +1,76 @@
+; RUN: not llc -march=bpfel < %s 2>&1 >/dev/null | FileCheck %s
+
+;; CHECK-NOT: nowarn
+define void @nowarn() local_unnamed_addr #0 !dbg !6 {
+  %1 = alloca [504 x i8], align 1
+  %2 = getelementptr inbounds [504 x i8], [504 x i8]* %1, i64 0, i64 0, !dbg !15
+  call void @llvm.lifetime.start(i64 504, i8* nonnull %2) #4, !dbg !15
+  tail call void @llvm.dbg.declare(metadata [504 x i8]* %1, metadata !10, metadata !16), !dbg !17
+  call void @doit(i8* nonnull %2) #4, !dbg !18
+  call void @llvm.lifetime.end(i64 504, i8* nonnull %2) #4, !dbg !19
+  ret void, !dbg !19
+}
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.start(i64, i8* nocapture) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
+
+declare void @doit(i8*) local_unnamed_addr #3
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.end(i64, i8* nocapture) #1
+
+; CHECK: error: warn_stack.c
+; CHECK: BPF stack limit
+define void @warn() local_unnamed_addr #0 !dbg !20 {
+  %1 = alloca [512 x i8], align 1
+  %2 = getelementptr inbounds [512 x i8], [512 x i8]* %1, i64 0, i64 0, !dbg !26
+  call void @llvm.lifetime.start(i64 512, i8* nonnull %2) #4, !dbg !26
+  tail call void @llvm.dbg.declare(metadata [512 x i8]* %1, metadata !22, metadata !16), !dbg !27
+  call void @doit(i8* nonnull %2) #4, !dbg !28
+  call void @llvm.lifetime.end(i64 512, i8* nonnull %2) #4, !dbg !29
+  ret void, !dbg !29
+}
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind }
+attributes #2 = { nounwind readnone }
+attributes #3 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 5.0.0 (trunk 292141) (llvm/trunk 292156)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "warn_stack.c", directory: "/w/llvm/bld")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 5.0.0 (trunk 292141) (llvm/trunk 292156)"}
+!6 = distinct !DISubprogram(name: "nowarn", scope: !1, file: !1, line: 2, type: !7, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !9)
+!7 = !DISubroutineType(types: !8)
+!8 = !{null}
+!9 = !{!10}
+!10 = !DILocalVariable(name: "buf", scope: !6, file: !1, line: 4, type: !11)
+!11 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, size: 4088, elements: !13)
+!12 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!13 = !{!14}
+!14 = !DISubrange(count: 504)
+!15 = !DILocation(line: 4, column: 2, scope: !6)
+!16 = !DIExpression()
+!17 = !DILocation(line: 4, column: 7, scope: !6)
+!18 = !DILocation(line: 5, column: 2, scope: !6)
+!19 = !DILocation(line: 6, column: 1, scope: !6)
+!20 = distinct !DISubprogram(name: "warn", scope: !1, file: !1, line: 7, type: !7, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !21)
+!21 = !{!22}
+!22 = !DILocalVariable(name: "buf", scope: !20, file: !1, line: 9, type: !23)
+!23 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, size: 4096, elements: !24)
+!24 = !{!25}
+!25 = !DISubrange(count: 512)
+!26 = !DILocation(line: 9, column: 2, scope: !20)
+!27 = !DILocation(line: 9, column: 7, scope: !20)
+!28 = !DILocation(line: 10, column: 2, scope: !20)
+!29 = !DILocation(line: 11, column: 1, scope: !20)