Index: lld/trunk/COFF/Driver.cpp
===================================================================
--- lld/trunk/COFF/Driver.cpp
+++ lld/trunk/COFF/Driver.cpp
@@ -1177,6 +1177,8 @@
 
   // Make sure we have resolved all symbols.
   Symtab->reportRemainingUndefines();
+  if (ErrorCount)
+    return;
 
   // Windows specific -- if no /subsystem is given, we need to infer
   // that from entry point name.
Index: lld/trunk/COFF/SymbolTable.cpp
===================================================================
--- lld/trunk/COFF/SymbolTable.cpp
+++ lld/trunk/COFF/SymbolTable.cpp
@@ -84,8 +84,16 @@
   Driver->parseDirectives(S);
 }
 
+static void errorOrWarn(const Twine &S) {
+  if (Config->Force)
+    warn(S);
+  else
+    error(S);
+}
+
 void SymbolTable::reportRemainingUndefines() {
   SmallPtrSet<SymbolBody *, 8> Undefs;
+
   for (auto &I : Symtab) {
     Symbol *Sym = I.second;
     auto *Undef = dyn_cast<Undefined>(Sym->body());
@@ -93,7 +101,9 @@
       continue;
     if (!Sym->IsUsedInRegularObj)
       continue;
+
     StringRef Name = Undef->getName();
+
     // A weak alias may have been resolved, so check for that.
     if (Defined *D = Undef->getWeakAlias()) {
       // We resolve weak aliases by replacing the alias's SymbolBody with the
@@ -112,6 +122,7 @@
         Sym->Body = D->symbol()->Body;
       continue;
     }
+
     // If we can resolve a symbol by removing __imp_ prefix, do that.
     // This odd rule is for compatibility with MSVC linker.
     if (Name.startswith("__imp_")) {
@@ -124,23 +135,25 @@
         continue;
       }
     }
+
     // Remaining undefined symbols are not fatal if /force is specified.
     // They are replaced with dummy defined symbols.
     if (Config->Force)
       replaceBody<DefinedAbsolute>(Sym, Name, 0);
     Undefs.insert(Sym->body());
   }
+
   if (Undefs.empty())
     return;
+
   for (SymbolBody *B : Config->GCRoot)
     if (Undefs.count(B))
-      warn("<root>: undefined symbol: " + B->getName());
+      errorOrWarn("<root>: undefined symbol: " + B->getName());
+
   for (ObjFile *File : ObjFile::Instances)
     for (SymbolBody *Sym : File->getSymbols())
       if (Undefs.count(Sym))
-        warn(toString(File) + ": undefined symbol: " + Sym->getName());
-  if (!Config->Force)
-    fatal("link failed");
+        errorOrWarn(toString(File) + ": undefined symbol: " + Sym->getName());
 }
 
 std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
Index: lld/trunk/test/COFF/entry-inference.test
===================================================================
--- lld/trunk/test/COFF/entry-inference.test
+++ lld/trunk/test/COFF/entry-inference.test
@@ -14,10 +14,10 @@
 # RUN: not lld-link /out:%t.exe %t.obj > %t.log 2>&1
 # RUN: FileCheck -check-prefix=WWINMAIN %s < %t.log
 
-# MAIN:     <root>: undefined symbol: mainCRTStartup
-# WMAIN:    <root>: undefined symbol: wmainCRTStartup
-# WINMAIN:  <root>: undefined symbol: WinMainCRTStartup
-# WWINMAIN: <root>: undefined symbol: wWinMainCRTStartup
+# MAIN:     error: <root>: undefined symbol: mainCRTStartup
+# WMAIN:    error: <root>: undefined symbol: wmainCRTStartup
+# WINMAIN:  error: <root>: undefined symbol: WinMainCRTStartup
+# WWINMAIN: error: <root>: undefined symbol: wWinMainCRTStartup
 
 --- !COFF
 header:
Index: lld/trunk/test/COFF/force.test
===================================================================
--- lld/trunk/test/COFF/force.test
+++ lld/trunk/test/COFF/force.test
@@ -1,10 +1,11 @@
 # RUN: yaml2obj < %s > %t.obj
 # RUN: not lld-link /out:%t.exe /entry:main %t.obj >& %t.log
-# RUN: FileCheck %s < %t.log
+# RUN: FileCheck -check-prefix=ERROR %s < %t.log
 # RUN: lld-link /out:%t.exe /entry:main %t.obj /force >& %t.log
-# RUN: FileCheck %s < %t.log
+# RUN: FileCheck -check-prefix=WARN %s < %t.log
 
-# CHECK: .obj: undefined symbol: foo
+# ERROR: error: {{.*}}.obj: undefined symbol: foo
+# WARN: warning: {{.*}}.obj: undefined symbol: foo
 
 --- !COFF
 header:
Index: lld/trunk/test/COFF/nodefaultlib.test
===================================================================
--- lld/trunk/test/COFF/nodefaultlib.test
+++ lld/trunk/test/COFF/nodefaultlib.test
@@ -19,9 +19,9 @@
 # RUN:   /nodefaultlib:std64.lib >& %t.log || true
 # RUN: FileCheck -check-prefix=CHECK3 %s < %t.log
 
-CHECK1: hello64.obj: {{[Nn]}}o such file or directory
-CHECK2: hello64: {{[Nn]}}o such file or directory
-CHECK3: hello64.obj: undefined symbol: MessageBoxA
+CHECK1: error: could not open hello64.obj: {{[Nn]}}o such file or directory
+CHECK2: error: could not open hello64: {{[Nn]}}o such file or directory
+CHECK3: error: {{.*}}hello64.obj: undefined symbol: MessageBoxA
 
 # RUN: lld-link /libpath:%T /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64.lib