Index: lld/COFF/Driver.cpp
===================================================================
--- lld/COFF/Driver.cpp
+++ lld/COFF/Driver.cpp
@@ -19,6 +19,7 @@
 #include "lld/Common/Args.h"
 #include "lld/Common/Driver.h"
 #include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Timer.h"
 #include "lld/Common/Version.h"
@@ -1273,6 +1274,12 @@
         getOutputPath((*Args.filtered(OPT_INPUT).begin())->getValue());
   }
 
+  // Fail early if an output file is not writable.
+  if (auto E = tryCreateFile(Config->OutputFile)) {
+    error("cannot open output file " + Config->OutputFile + ": " + E.message());
+    return;
+  }
+
   // Put the PDB next to the image if no /pdb flag was passed.
   if (ShouldCreatePDB && Config->PDBPath.empty()) {
     Config->PDBPath = Config->OutputFile;
Index: lld/Common/CMakeLists.txt
===================================================================
--- lld/Common/CMakeLists.txt
+++ lld/Common/CMakeLists.txt
@@ -5,6 +5,7 @@
 add_lld_library(lldCommon
   Args.cpp
   ErrorHandler.cpp
+  Filesystem.cpp
   Memory.cpp
   Reproduce.cpp
   Strings.cpp
Index: lld/Common/Filesystem.cpp
===================================================================
--- lld/Common/Filesystem.cpp
+++ lld/Common/Filesystem.cpp
@@ -11,8 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "Filesystem.h"
-#include "Config.h"
+#include "lld/Common/Filesystem.h"
 #include "lld/Common/Threads.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/FileOutputBuffer.h"
@@ -23,9 +22,7 @@
 #include <thread>
 
 using namespace llvm;
-
 using namespace lld;
-using namespace lld::elf;
 
 // Removes a given file asynchronously. This is a performance hack,
 // so remove this when operating systems are improved.
@@ -42,7 +39,7 @@
 //
 // This function spawns a background thread to remove the file.
 // The calling thread returns almost immediately.
-void elf::unlinkAsync(StringRef Path) {
+void lld::unlinkAsync(StringRef Path) {
 // Removing a file is async on windows.
 #if defined(LLVM_ON_WIN32)
   sys::fs::remove(Path);
@@ -77,7 +74,7 @@
 // FileOutputBuffer doesn't touch a desitnation file until commit()
 // is called. We use that class without calling commit() to predict
 // if the given file is writable.
-std::error_code elf::tryCreateFile(StringRef Path) {
+std::error_code lld::tryCreateFile(StringRef Path) {
   if (Path.empty())
     return std::error_code();
   if (Path == "-")
Index: lld/ELF/CMakeLists.txt
===================================================================
--- lld/ELF/CMakeLists.txt
+++ lld/ELF/CMakeLists.txt
@@ -22,7 +22,6 @@
   Driver.cpp
   DriverUtils.cpp
   EhFrame.cpp
-  Filesystem.cpp
   GdbIndex.cpp
   ICF.cpp
   InputFiles.cpp
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -25,7 +25,6 @@
 
 #include "Driver.h"
 #include "Config.h"
-#include "Filesystem.h"
 #include "ICF.h"
 #include "InputFiles.h"
 #include "InputSection.h"
@@ -42,6 +41,7 @@
 #include "lld/Common/Args.h"
 #include "lld/Common/Driver.h"
 #include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/TargetOptionsCommandFlags.h"
 #include "lld/Common/Threads.h"
Index: lld/ELF/Writer.cpp
===================================================================
--- lld/ELF/Writer.cpp
+++ lld/ELF/Writer.cpp
@@ -10,7 +10,6 @@
 #include "Writer.h"
 #include "AArch64ErrataFix.h"
 #include "Config.h"
-#include "Filesystem.h"
 #include "LinkerScript.h"
 #include "MapFile.h"
 #include "OutputSections.h"
@@ -20,6 +19,7 @@
 #include "Symbols.h"
 #include "SyntheticSections.h"
 #include "Target.h"
+#include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Threads.h"
 #include "llvm/ADT/StringMap.h"
Index: lld/include/lld/Common/Filesystem.h
===================================================================
--- lld/include/lld/Common/Filesystem.h
+++ lld/include/lld/Common/Filesystem.h
@@ -7,17 +7,15 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLD_ELF_FILESYSTEM_H
-#define LLD_ELF_FILESYSTEM_H
+#ifndef LLD_COMMON_FILESYSTEM_H
+#define LLD_COMMON_FILESYSTEM_H
 
 #include "lld/Common/LLVM.h"
 #include <system_error>
 
 namespace lld {
-namespace elf {
 void unlinkAsync(StringRef Path);
 std::error_code tryCreateFile(StringRef Path);
-} // namespace elf
 } // namespace lld
 
 #endif
Index: lld/test/COFF/driver.test
===================================================================
--- lld/test/COFF/driver.test
+++ lld/test/COFF/driver.test
@@ -4,3 +4,7 @@
 
 # RUN: lld-link --version | FileCheck -check-prefix=VERSION %s
 VERSION: {{LLD [0-9]+\.[0-9]+}}
+
+# RUN: yaml2obj < %p/Inputs/hello32.yaml > %t.obj
+# RUN: not lld-link /out:/ %t.obj 2>&1 | FileCheck -check-prefix=DIR %s
+DIR: cannot open output file