diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -266,6 +266,8 @@
   bool seenGnuAbi() const { return SeenGnuAbi; }
   void emitAddrsigSection() override { EmitAddrsigSection = true; }
   void addAddrsigSymbol(const MCSymbol *Sym) override {
+    const MCSymbolELF *S = cast<MCSymbolELF>(Sym);
+    S->setBinding(ELF::STB_WEAK);
     AddrsigSyms.push_back(Sym);
   }
 
diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -218,7 +218,9 @@
 
   void emitAddrsigSection() override { EmitAddrsigSection = true; }
   void addAddrsigSymbol(const MCSymbol *Sym) override {
-    AddrsigSyms.push_back(Sym);
+    const MCSymbolCOFF *S = cast<MCSymbolCOFF>(Sym);
+    S->setIsWeakExternal();
+    AddrsigSyms.push_back(S);
   }
 
   uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
diff --git a/llvm/test/MC/COFF/addrsig.s b/llvm/test/MC/COFF/addrsig.s
--- a/llvm/test/MC/COFF/addrsig.s
+++ b/llvm/test/MC/COFF/addrsig.s
@@ -14,7 +14,7 @@
 // CHECK-NEXT:   IMAGE_SCN_LNK_REMOVE (0x800)
 // CHECK-NEXT: ]
 // CHECK-NEXT: SectionData (
-// CHECK-NEXT:   0000: 080A0B02
+// CHECK-NEXT:   0000: 080C0F02
 // CHECK-NEXT: )
 
 // CHECK: Symbols [
@@ -27,14 +27,41 @@
 // CHECK: Name: .llvm_addrsig
 // CHECK: AuxSectionDef
 // CHECK: Name: g1
+// CHECK-NEXT: Value: 0
+// CHECK-NEXT: Section: IMAGE_SYM_UNDEFINED (0)
+// CHECK-NEXT: BaseType: Null (0x0)
+// CHECK-NEXT: ComplexType: Null (0x0)
+// CHECK-NEXT: StorageClass: WeakExternal (0x69)
+// CHECK-NEXT: AuxSymbolCount: 1
+// CHECK-NEXT: AuxWeakExternal {
+// CHECK-NEXT: Linked: .weak.g1.default (10)
+// CHECK-NEXT: Search: Alias (0x3)
 // CHECK: Name: g2
 // CHECK: Name: g3
+// CHECK-NEXT: Value: 0
+// CHECK-NEXT: Section: IMAGE_SYM_UNDEFINED (0)
+// CHECK-NEXT: BaseType: Null (0x0)
+// CHECK-NEXT: ComplexType: Null (0x0)
+// CHECK-NEXT: StorageClass: WeakExternal (0x69)
+// CHECK-NEXT: AuxSymbolCount: 1
+// CHECK-NEXT: AuxWeakExternal {
+// CHECK-NEXT: Linked: .weak.g3.default (14)
+// CHECK-NEXT: Search: Alias (0x3)
 // CHECK: Name: local
+// CHECK-NEXT: Value: 0
+// CHECK-NEXT: Section: IMAGE_SYM_UNDEFINED (0)
+// CHECK-NEXT: BaseType: Null (0x0)
+// CHECK-NEXT: ComplexType: Null (0x0)
+// CHECK-NEXT: StorageClass: WeakExternal (0x69)
+// CHECK-NEXT: AuxSymbolCount: 1
+// CHECK-NEXT: AuxWeakExternal {
+// CHECK-NEXT: Linked: .weak.local.default (17)
+// CHECK-NEXT: Search: Alias (0x3)
 
 // CHECK:      Addrsig [
 // CHECK-NEXT:   Sym: g1 (8)
-// CHECK-NEXT:   Sym: g3 (10)
-// CHECK-NEXT:   Sym: local (11)
+// CHECK-NEXT:   Sym: g3 (12)
+// CHECK-NEXT:   Sym: local (15)
 // CHECK-NEXT:   Sym: .data (2)
 // CHECK-NEXT: ]
 
diff --git a/llvm/test/MC/ELF/addrsig.s b/llvm/test/MC/ELF/addrsig.s
--- a/llvm/test/MC/ELF/addrsig.s
+++ b/llvm/test/MC/ELF/addrsig.s
@@ -16,7 +16,7 @@
 // CHECK-NEXT:   AddressAlignment: 1
 // CHECK-NEXT:   EntrySize: 0
 // CHECK-NEXT:   SectionData (
-// CHECK-NEXT:     0000: 03050201
+// CHECK-NEXT:     0000: 02040501
 // CHECK-NEXT:   )
 // CHECK-NEXT: }
 // CHECK-NEXT: Section {
@@ -34,16 +34,16 @@
 // CHECK-NEXT:   Section: [[SEC:.*]]
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
-// CHECK-NEXT:   Name: local
+// CHECK-NEXT:   Name: g1
 // CHECK-NEXT:   Value:
 // CHECK-NEXT:   Size:
-// CHECK-NEXT:   Binding:
+// CHECK-NEXT:   Binding: Weak
 // CHECK-NEXT:   Type:
 // CHECK-NEXT:   Other:
-// CHECK-NEXT:   Section: [[SEC]]
+// CHECK-NEXT:   Section:
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
-// CHECK-NEXT:   Name: g1
+// CHECK-NEXT:   Name: g2
 // CHECK-NEXT:   Value:
 // CHECK-NEXT:   Size:
 // CHECK-NEXT:   Binding:
@@ -52,21 +52,28 @@
 // CHECK-NEXT:   Section:
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
-// CHECK-NEXT:   Name: g2
+// CHECK-NEXT:   Name: g3
 // CHECK-NEXT:   Value:
 // CHECK-NEXT:   Size:
-// CHECK-NEXT:   Binding:
+// CHECK-NEXT:   Binding: Weak
 // CHECK-NEXT:   Type:
 // CHECK-NEXT:   Other:
 // CHECK-NEXT:   Section:
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
-// CHECK-NEXT:   Name: g3
+// CHECK-NEXT:   Name: local
+// CHECK-NEXT:   Value:
+// CHECK-NEXT:   Size:
+// CHECK-NEXT:   Binding: Weak
+// CHECK-NEXT:   Type:
+// CHECK-NEXT:   Other:
+// CHECK-NEXT:   Section: [[SEC]]
+// CHECK-NEXT: }
 
 // CHECK:      Addrsig [
-// CHECK-NEXT:   Sym: g1 (3)
-// CHECK-NEXT:   Sym: g3 (5)
-// CHECK-NEXT:   Sym: local (2)
+// CHECK-NEXT:   Sym: g1 (2)
+// CHECK-NEXT:   Sym: g3 (4)
+// CHECK-NEXT:   Sym: local (5)
 // CHECK-NEXT:   Sym:  (1)
 // CHECK-NEXT: ]