Index: lld/trunk/COFF/Driver.cpp
===================================================================
--- lld/trunk/COFF/Driver.cpp
+++ lld/trunk/COFF/Driver.cpp
@@ -548,42 +548,92 @@
   }
 }
 
-// Get a set of symbols not to automatically export
-// when exporting all global symbols for MinGW.
-static StringSet<> getExportExcludeSymbols() {
-  if (Config->Machine == I386)
-    return {
-        "__NULL_IMPORT_DESCRIPTOR",
-        "__pei386_runtime_relocator",
-        "_do_pseudo_reloc",
-        "_impure_ptr",
-        "__impure_ptr",
-        "__fmode",
-        "_environ",
-        "___dso_handle",
-        // These are the MinGW names that differ from the standard
-        // ones (lacking an extra underscore).
-        "_DllMain@12",
-        "_DllEntryPoint@12",
-        "_DllMainCRTStartup@12",
-    };
-
-  return {
-      "_NULL_IMPORT_DESCRIPTOR",
-      "_pei386_runtime_relocator",
-      "do_pseudo_reloc",
-      "impure_ptr",
-      "_impure_ptr",
-      "_fmode",
-      "environ",
-      "__dso_handle",
-      // These are the MinGW names that differ from the standard
-      // ones (lacking an extra underscore).
-      "DllMain",
-      "DllEntryPoint",
-      "DllMainCRTStartup",
+// Logic for deciding what symbols to export, when exporting all
+// symbols for MinGW.
+class AutoExporter {
+public:
+  AutoExporter() {
+    if (Config->Machine == I386)
+      ExcludeSymbols = {
+          "__NULL_IMPORT_DESCRIPTOR",
+          "__pei386_runtime_relocator",
+          "_do_pseudo_reloc",
+          "_impure_ptr",
+          "__impure_ptr",
+          "__fmode",
+          "_environ",
+          "___dso_handle",
+          // These are the MinGW names that differ from the standard
+          // ones (lacking an extra underscore).
+          "_DllMain@12",
+          "_DllEntryPoint@12",
+          "_DllMainCRTStartup@12",
+      };
+    else
+      ExcludeSymbols = {
+          "_NULL_IMPORT_DESCRIPTOR",
+          "_pei386_runtime_relocator",
+          "do_pseudo_reloc",
+          "impure_ptr",
+          "_impure_ptr",
+          "_fmode",
+          "environ",
+          "__dso_handle",
+          // These are the MinGW names that differ from the standard
+          // ones (lacking an extra underscore).
+          "DllMain",
+          "DllEntryPoint",
+          "DllMainCRTStartup",
+      };
+  }
+
+  StringSet<> ExcludeSymbols;
+  StringSet<> ExcludeLibs = {
+      "libgcc",
+      "libgcc_s",
+      "libstdc++",
+      "libmingw32",
+      "libmingwex",
+      "libg2c",
+      "libsupc++",
+      "libobjc",
+      "libgcj",
+      "libclang_rt.builtins-aarch64",
+      "libclang_rt.builtins-arm",
+      "libclang_rt.builtins-i386",
+      "libclang_rt.builtins-x86_64",
+  };
+  StringSet<> ExcludeObjects = {
+      "crt0.o",
+      "crt1.o",
+      "crt1u.o",
+      "crt2.o",
+      "crt2u.o",
+      "dllcrt1.o",
+      "dllcrt2.o",
+      "gcrt0.o",
+      "gcrt1.o",
+      "gcrt2.o",
+      "crtbegin.o",
+      "crtend.o",
   };
-}
+
+  bool shouldExport(Defined *Sym) const {
+    if (!Sym || !Sym->isLive() || !Sym->getChunk())
+      return false;
+    if (ExcludeSymbols.count(Sym->getName()))
+      return false;
+    StringRef LibName = sys::path::filename(Sym->getFile()->ParentName);
+    // Drop the file extension.
+    LibName = LibName.substr(0, LibName.rfind('.'));
+    if (ExcludeLibs.count(LibName))
+      return false;
+    StringRef FileName = sys::path::filename(Sym->getFile()->getName());
+    if (LibName.empty() && ExcludeObjects.count(FileName))
+      return false;
+    return true;
+  }
+};
 
 // This is MinGW specific.
 static void writeDefFile(StringRef Name) {
@@ -1259,13 +1309,11 @@
   // are chosen to be exported.
   if (Config->DLL && ((Config->MinGW && Config->Exports.empty()) ||
                       Args.hasArg(OPT_export_all_symbols))) {
-    StringSet<> ExcludeSymbols = getExportExcludeSymbols();
+    AutoExporter Exporter;
 
     Symtab->forEachSymbol([=](Symbol *S) {
       auto *Def = dyn_cast<Defined>(S->body());
-      if (!Def || !Def->isLive() || !Def->getChunk())
-        return;
-      if (ExcludeSymbols.count(Def->getName()))
+      if (!Exporter.shouldExport(Def))
         return;
       Export E;
       E.Name = Def->getName();
Index: lld/trunk/test/COFF/export-all.s
===================================================================
--- lld/trunk/test/COFF/export-all.s
+++ lld/trunk/test/COFF/export-all.s
@@ -36,3 +36,21 @@
 # CHECK2-DEF: exportfn1 @3
 # CHECK2-DEF: exportfn2 @4
 # CHECK2-DEF: exportfn3 @5
+
+# Test ignoring certain object files and libs.
+
+# RUN: echo -e ".global foobar\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\nfoobar:\ncall mingwfunc\ncall crtfunc\nret\n" > %t.main.s
+# RUN: llvm-mc -triple=x86_64-windows-gnu %t.main.s -filetype=obj -o %t.main.obj
+# RUN: mkdir -p %T/libs
+# RUN: echo -e ".global mingwfunc\n.text\nmingwfunc:\nret\n" > %T/libs/mingwfunc.s
+# RUN: llvm-mc -triple=x86_64-windows-gnu %T/libs/mingwfunc.s -filetype=obj -o %T/libs/mingwfunc.o
+# RUN: llvm-ar rcs %T/libs/libmingwex.a %T/libs/mingwfunc.o
+# RUN: echo -e ".global crtfunc\n.text\ncrtfunc:\nret\n" > %T/libs/crtfunc.s
+# RUN: llvm-mc -triple=x86_64-windows-gnu %T/libs/crtfunc.s -filetype=obj -o %T/libs/crt2.o
+# RUN: lld-link -out:%t.dll -dll -entry:DllMainCRTStartup %t.main.obj -lldmingw %T/libs/crt2.o %T/libs/libmingwex.a -output-def:%t.def
+# RUN: echo "EOF" >> %t.def
+# RUN: cat %t.def | FileCheck -check-prefix=CHECK-EXCLUDE %s
+
+# CHECK-EXCLUDE: EXPORTS
+# CHECK-EXCLUDE-NEXT: foobar @1
+# CHECK-EXCLUDE-NEXT: EOF