diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -567,6 +567,11 @@
 
   auto *SP = cast<DISubprogram>(Scope->getScopeNode());
 
+  // Handling a case with LTO where function is inlined from CU which doesn't
+  // have SplitDebugInlining enabled into one that does.
+  if (SrcCU.getCUNode()->getSplitDebugInlining())
+    SP->getUnit()->setSplitDebugInlining(true);
+
   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
   // was inlined from another compile unit.
   if (useSplitDwarf() && !shareAcrossDWOCUs() && !SP->getUnit()->getSplitDebugInlining())
diff --git a/llvm/test/DebugInfo/Inputs/mixDebugInliingHelper.ll b/llvm/test/DebugInfo/Inputs/mixDebugInliingHelper.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/DebugInfo/Inputs/mixDebugInliingHelper.ll
@@ -0,0 +1,47 @@
+; -g2 -gsplit-dwarf=split -fdebug-info-for-profiling -flto=thin -c
+; int __attribute__((always_inline)) func(int x) {
+;    return x * 2;
+; }
+
+; ModuleID = 'helper.cpp'
+source_filename = "helper.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: alwaysinline nounwind uwtable mustprogress
+define dso_local i32 @_Z4funci(i32 %x) #0 !dbg !7 {
+entry:
+  %x.addr = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %x.addr, metadata !11, metadata !DIExpression()), !dbg !12
+  %0 = load i32, i32* %x.addr, align 4, !dbg !13
+  %mul = mul nsw i32 %0, 2, !dbg !14
+  ret i32 %mul, !dbg !15
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { alwaysinline nounwind uwtable mustprogress "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.1", isOptimized: true, runtimeVersion: 0, splitDebugFilename: "helper.dwo", emissionKind: FullDebug, enums: !2, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: GNU)
+!1 = !DIFile(filename: "helper.cpp", directory: "bug2")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.1"}
+!7 = distinct !DISubprogram(name: "func", linkageName: "_Z4funci", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!12 = !DILocation(line: 1, column: 45, scope: !7)
+!13 = !DILocation(line: 2, column: 11, scope: !7)
+!14 = !DILocation(line: 2, column: 13, scope: !7)
+!15 = !DILocation(line: 2, column: 4, scope: !7)
diff --git a/llvm/test/DebugInfo/Inputs/mixDebugInliingMain.ll b/llvm/test/DebugInfo/Inputs/mixDebugInliingMain.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/DebugInfo/Inputs/mixDebugInliingMain.ll
@@ -0,0 +1,61 @@
+; -g2 -gsplit-dwarf=split -fsplit-dwarf-inlining -fdebug-info-for-profiling -flto=thin
+; int func(int);
+; int main(int argc, char *argv[]) {
+;   return func(argc);;
+; }
+
+; ModuleID = 'main.cpp'
+source_filename = "main.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: noinline norecurse optnone uwtable mustprogress
+define dso_local i32 @main(i32 %argc, i8** %argv) #0 !dbg !7 {
+entry:
+  %retval = alloca i32, align 4
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 8
+  store i32 0, i32* %retval, align 4
+  store i32 %argc, i32* %argc.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %argc.addr, metadata !14, metadata !DIExpression()), !dbg !15
+  store i8** %argv, i8*** %argv.addr, align 8
+  call void @llvm.dbg.declare(metadata i8*** %argv.addr, metadata !16, metadata !DIExpression()), !dbg !17
+  %0 = load i32, i32* %argc.addr, align 4, !dbg !18
+  %call = call i32 @_Z4funci(i32 %0), !dbg !19
+  ret i32 %call, !dbg !20
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+declare dso_local i32 @_Z4funci(i32) #2
+
+attributes #0 = { noinline norecurse optnone uwtable mustprogress "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
+attributes #2 = { "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.1", isOptimized: true, runtimeVersion: 0, splitDebugFilename: "main.dwo", emissionKind: FullDebug, enums: !2, debugInfoForProfiling: true, nameTableKind: GNU)
+!1 = !DIFile(filename: "main.cpp", directory: "bug2")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.1"}
+!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64)
+!13 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!14 = !DILocalVariable(name: "argc", arg: 1, scope: !7, file: !1, line: 2, type: !10)
+!15 = !DILocation(line: 2, column: 14, scope: !7)
+!16 = !DILocalVariable(name: "argv", arg: 2, scope: !7, file: !1, line: 2, type: !11)
+!17 = !DILocation(line: 2, column: 26, scope: !7)
+!18 = !DILocation(line: 3, column: 15, scope: !7)
+!19 = !DILocation(line: 3, column: 10, scope: !7)
+!20 = !DILocation(line: 3, column: 3, scope: !7)
diff --git a/llvm/test/DebugInfo/X86/mixDebugInliing.test b/llvm/test/DebugInfo/X86/mixDebugInliing.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/mixDebugInliing.test
@@ -0,0 +1,29 @@
+; RUN: llvm-as %p/../Inputs/mixDebugInliingMain.ll -o %tMain.o
+; RUN: llvm-as %p/../Inputs/mixDebugInliingHelper.ll -o %tHelper.o
+; RUN: clang++ -fuse-ld=lld -flto=thin -Wl,--plugin-opt=dwo_dir="." %tMain.o %tHelper.o -o %t.exe
+; RUN: llvm-dwarfdump --debug-info --show-form --verbose %t.exe | FileCheck -check-prefix=CHECK %s
+
+; CHECK:        DW_TAG_compile_unit
+; CHECK-NEXT:       DW_AT_stmt_list
+; CHECK-NEXT:       DW_AT_comp_dir
+; CHECK-NEXT:       DW_AT_GNU_pubnames
+; CHECK-NEXT:       DW_AT_GNU_dwo_name
+; CHECK-NEXT:       DW_AT_GNU_dwo_id
+; CHECK-NEXT:       DW_AT_low_pc
+; CHECK-NEXT:       DW_AT_high_pc
+; CHECK-NEXT:       DW_AT_GNU_addr_base
+; CHECK-EMPTY:
+; CHECK-NEXT:   DW_TAG_subprogram
+; CHECK-NEXT:       DW_AT_low_pc
+; CHECK-NEXT:       DW_AT_high_pc
+; CHECK-NEXT:       DW_AT_name
+; CHECK-NEXT:       DW_AT_decl_file
+; CHECK-NEXT:       DW_AT_decl_line
+; CHECK-EMPTY:
+; CHECK-NEXT:   DW_TAG_inlined_subroutine
+; CHECK-NEXT:       DW_AT_abstract_origin
+; CHECK-NEXT:       DW_AT_low_pc
+; CHECK-NEXT:       DW_AT_high_pc
+; CHECK-NEXT:       DW_AT_call_file
+; CHECK-NEXT:       DW_AT_call_line
+; CHECK-NEXT:       DW_AT_call_column