Index: llvm/lib/MC/WinCOFFObjectWriter.cpp
===================================================================
--- llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -411,6 +411,11 @@
       Local->Data.StorageClass = IsExternal ? COFF::IMAGE_SYM_CLASS_EXTERNAL
                                             : COFF::IMAGE_SYM_CLASS_STATIC;
     }
+    // If the original symbol was weak, and we created a new default
+    // symbol here, make it static, in order to not conflict with similar
+    // default symbols for the same weak in other translation units.
+    if (SymbolCOFF.isWeakExternal())
+      Local->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
   }
 
   Sym->MC = &MCSym;
Index: llvm/test/MC/COFF/weak-alias-local.s
===================================================================
--- llvm/test/MC/COFF/weak-alias-local.s
+++ llvm/test/MC/COFF/weak-alias-local.s
@@ -38,6 +38,6 @@
 // CHECK-NEXT:   Section: .data (2)
 // CHECK-NEXT:   BaseType: Null (0x0)
 // CHECK-NEXT:   ComplexType: Null (0x0)
-// CHECK-NEXT:   StorageClass: External (0x2)
+// CHECK-NEXT:   StorageClass: Static (0x3)
 // CHECK-NEXT:   AuxSymbolCount: 0
 // CHECK-NEXT: }
Index: llvm/test/MC/COFF/weak-val.s
===================================================================
--- llvm/test/MC/COFF/weak-val.s
+++ llvm/test/MC/COFF/weak-val.s
@@ -28,6 +28,6 @@
 // CHECK-NEXT:   Section: .data (2)
 // CHECK-NEXT:   BaseType: Null (0x0)
 // CHECK-NEXT:   ComplexType: Null (0x0)
-// CHECK-NEXT:   StorageClass: External (0x2)
+// CHECK-NEXT:   StorageClass: Static (0x3)
 // CHECK-NEXT:   AuxSymbolCount: 0
 // CHECK-NEXT: }
Index: llvm/test/MC/COFF/weak.s
===================================================================
--- llvm/test/MC/COFF/weak.s
+++ llvm/test/MC/COFF/weak.s
@@ -64,7 +64,7 @@
 // CHECK-NEXT:   Section:             IMAGE_SYM_ABSOLUTE (-1)
 // CHECK-NEXT:   BaseType:            Null
 // CHECK-NEXT:   ComplexType:         Null
-// CHECK-NEXT:   StorageClass:        External
+// CHECK-NEXT:   StorageClass:        Static
 // CHECK-NEXT:   AuxSymbolCount:      0
 // CHECK-NEXT: }
 
@@ -88,6 +88,6 @@
 // CHECK-NEXT:   Section: .text
 // CHECK-NEXT:   BaseType: Null
 // CHECK-NEXT:   ComplexType: Null
-// CHECK-NEXT:   StorageClass: External
+// CHECK-NEXT:   StorageClass: Static
 // CHECK-NEXT:   AuxSymbolCount: 0
 // CHECK-NEXT: }