Index: llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -197,9 +197,7 @@
   // together.
   if (isDwoUnit() && !DD->shareAcrossDWOCUs())
     return false;
-  return (isa<DIType>(D) ||
-          (isa<DISubprogram>(D) && !cast<DISubprogram>(D)->isDefinition())) &&
-         !DD->generateTypeUnits();
+  return (isa<DIType>(D) || isa<DISubprogram>(D)) && !DD->generateTypeUnits();
 }
 
 DIE *DwarfUnit::getDIE(const DINode *D) const {
Index: llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/lto-cross-cu-call-origin-ref.ll
@@ -0,0 +1,84 @@
+; RUN: llc -mtriple=x86_64-apple-darwin -filetype=obj < %s | llvm-dwarfdump - \
+; RUN:   | FileCheck %s
+
+; Source:
+
+;; // a.c
+;; __attribute__((optnone)) void bar() {}
+;; __attribute__((always_inline)) void foo() { bar(); }
+
+;; // b.c
+;; extern void foo();
+;; int main() {
+;;   foo();
+;;   return 0;
+;; }
+
+; Command:
+;; clang -O2 -Xclang -femit-debug-entry-values -g -flto -o a.o -c a.c
+;; clang -O2 -Xclang -femit-debug-entry-values -g -flto -o b.o -c b.c
+;; clang -O2 -Xclang -femit-debug-entry-values -g -flto -o main a.o b.o -Wl,-object_path_lto,lto.o,-save-temps
+
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_AT_name ("a.c")
+
+; Check for a definition subprogram for "bar". Note that AT_call_all_calls
+; implies that this is not a declaration.
+; CHECK: 0x[[BAR_DIE:.*]]: DW_TAG_subprogram
+; CHECK: DW_AT_call_all_calls    (true)
+; CHECK: DW_AT_name      ("bar")
+
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_AT_name ("b.c")
+
+; Check that "main" can reference the definition of "bar" in "a.c". (Previously
+; we would not share definition subprograms across CUs, so the call site info
+; logic would create an empty 'definition' subprogram for "bar" which never got
+; filled in. This breaks both entry value evaluation & artificial tail call
+; frame synthesis in the LTO setting.)
+; CHECK: DW_TAG_subprogram
+; CHECK: DW_AT_name      ("main")
+; CHECK:     DW_TAG_call_site
+; CHECK-NEXT: DW_AT_call_origin (0x{{.*}}[[BAR_DIE]])
+
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.14.0"
+
+define internal fastcc void @bar() unnamed_addr #0 !dbg !11 {
+  ret void, !dbg !14
+}
+
+define i32 @main() local_unnamed_addr !dbg !15 {
+  tail call fastcc void @bar(), !dbg !19
+  ret i32 0, !dbg !22
+}
+
+attributes #0 = { noinline optnone }
+
+!llvm.dbg.cu = !{!0, !3}
+!llvm.ident = !{!5, !5}
+!llvm.module.flags = !{!6, !7, !8, !9, !10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: GNU)
+!1 = !DIFile(filename: "a.c", directory: "/Users/vsk/tmp/lto-entry-vals")
+!2 = !{}
+!3 = distinct !DICompileUnit(language: DW_LANG_C99, file: !4, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: GNU)
+!4 = !DIFile(filename: "b.c", directory: "/Users/vsk/tmp/lto-entry-vals")
+!5 = !{!"Apple clang version 11.0.3 (clang-1103.0.22.93)"}
+!6 = !{i32 2, !"SDK Version", [2 x i32] [i32 10, i32 14]}
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{i32 7, !"PIC Level", i32 2}
+!11 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 1, type: !12, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!12 = !DISubroutineType(types: !13)
+!13 = !{null}
+!14 = !DILocation(line: 1, column: 38, scope: !11)
+!15 = distinct !DISubprogram(name: "main", scope: !4, file: !4, line: 2, type: !16, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !2)
+!16 = !DISubroutineType(types: !17)
+!17 = !{!18}
+!18 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!19 = !DILocation(line: 2, column: 45, scope: !20, inlinedAt: !21)
+!20 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !12, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!21 = distinct !DILocation(line: 3, column: 3, scope: !15)
+!22 = !DILocation(line: 4, column: 3, scope: !15)