Index: clang/lib/Driver/ToolChains/CommonArgs.cpp
===================================================================
--- clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1228,6 +1228,8 @@
   case ToolChain::UNW_CompilerRT:
     if (LGT == LibGccType::StaticLibGcc)
       CmdArgs.push_back("-l:libunwind.a");
+    else if (TC.getTriple().isOSCygMing())
+      CmdArgs.push_back("-l:libunwind.dll.a");
     else
       CmdArgs.push_back("-l:libunwind.so");
     break;