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
@@ -352,9 +352,10 @@
 
 /// This function takes a symbol data object from the assembler
 /// and creates the associated COFF symbol staging object.
-void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &MCSym,
+void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &MCSymGeneric,
                                        MCAssembler &Assembler,
                                        const MCAsmLayout &Layout) {
+  const auto &MCSym = cast<MCSymbolCOFF>(MCSymGeneric);
   COFFSymbol *Sym = GetOrCreateCOFFSymbol(&MCSym);
   const MCSymbol *Base = Layout.getBaseSymbol(MCSym);
   COFFSection *Sec = nullptr;
@@ -365,7 +366,7 @@
   }
 
   COFFSymbol *Local = nullptr;
-  if (cast<MCSymbolCOFF>(MCSym).isWeakExternal()) {
+  if (MCSym.isWeakExternal()) {
     Sym->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
 
     COFFSymbol *WeakDefault = getLinkedSymbol(MCSym);
@@ -376,6 +377,9 @@
         WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
       else
         WeakDefault->Section = Sec;
+      // Make the default symbol static, in order to not conflict with
+      // similar default symbols for the same weak in other objects.
+      WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
       Local = WeakDefault;
     }
 
@@ -394,14 +398,8 @@
     else
       Sym->Section = Sec;
     Local = Sym;
-  }
 
-  if (Local) {
-    Local->Data.Value = getSymbolValue(MCSym, Layout);
-
-    const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(MCSym);
-    Local->Data.Type = SymbolCOFF.getType();
-    Local->Data.StorageClass = SymbolCOFF.getClass();
+    Local->Data.StorageClass = MCSym.getClass();
 
     // If no storage class was specified in the streamer, define it here.
     if (Local->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
@@ -413,6 +411,12 @@
     }
   }
 
+  if (Local) {
+    Local->Data.Value = getSymbolValue(MCSym, Layout);
+
+    Local->Data.Type = MCSym.getType();
+  }
+
   Sym->MC = &MCSym;
 }
 
diff --git a/llvm/test/MC/COFF/weak-alias-local.s b/llvm/test/MC/COFF/weak-alias-local.s
--- a/llvm/test/MC/COFF/weak-alias-local.s
+++ b/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: }
diff --git a/llvm/test/MC/COFF/weak-val.s b/llvm/test/MC/COFF/weak-val.s
--- a/llvm/test/MC/COFF/weak-val.s
+++ b/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: }
diff --git a/llvm/test/MC/COFF/weak.s b/llvm/test/MC/COFF/weak.s
--- a/llvm/test/MC/COFF/weak.s
+++ b/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: }