Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -42,6 +42,7 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/TargetSelect.h"
@@ -501,6 +502,30 @@
   return Ret;
 }
 
+// Gets a path for an output file, or emits an error if the path specified is
+// not a valid file path.
+static StringRef getOutputFilePath(opt::InputArgList &Args, unsigned Key,
+                                   bool PerformPathChecks) {
+  StringRef OutputPath = getString(Args, Key);
+  if (OutputPath.empty() || !PerformPathChecks)
+    return OutputPath;
+
+  auto *Arg = Args.getLastArg(Key);
+  assert(Arg != nullptr && "expected argument in list");
+  auto OptionName = Arg->getSpelling();
+
+  if (sys::fs::is_directory(OutputPath)) {
+    error(OptionName + ": " + OutputPath + " is a directory");
+    return OutputPath;
+  }
+
+  StringRef ParentPath = sys::path::parent_path(OutputPath);
+  if (!ParentPath.empty() && !sys::fs::is_directory(ParentPath)) {
+    error(OptionName + ": cannot write to " + OutputPath);
+  }
+  return OutputPath;
+}
+
 // Initializes Config members by the command line options.
 void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   for (auto *Arg : Args.filtered(OPT_L))
@@ -560,9 +585,15 @@
   Config->Init = getString(Args, OPT_init, "_init");
   Config->LTOAAPipeline = getString(Args, OPT_lto_aa_pipeline);
   Config->LTONewPmPasses = getString(Args, OPT_lto_newpm_passes);
-  Config->MapFile = getString(Args, OPT_Map);
-  Config->OptRemarksFilename = getString(Args, OPT_opt_remarks_filename);
-  Config->OutputFile = getString(Args, OPT_o);
+
+  bool PerformPathChecks = !Args.hasArg(OPT_no_early_path_checks);
+  Config->MapFile =
+      getOutputFilePath(Args, OPT_Map, PerformPathChecks);
+  Config->OptRemarksFilename = getOutputFilePath(
+      Args, OPT_opt_remarks_filename, PerformPathChecks);
+  Config->OutputFile =
+      getOutputFilePath(Args, OPT_o, PerformPathChecks);
+
   Config->SoName = getString(Args, OPT_soname);
   Config->Sysroot = getString(Args, OPT_sysroot);
 
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -151,6 +151,9 @@
 def no_dynamic_linker: F<"no-dynamic-linker">,
   HelpText<"Inhibit output of .interp section">;
 
+def no_early_path_checks: F<"no-early-path-checks">,
+  HelpText<"Disable early checks for valid output file paths">;
+
 def no_export_dynamic: F<"no-export-dynamic">;
 def no_fatal_warnings: F<"no-fatal-warnings">;
 
Index: test/ELF/driver.test
===================================================================
--- test/ELF/driver.test
+++ test/ELF/driver.test
@@ -10,7 +10,7 @@
 # UNKNOWN: unable to find library -lnosuchlib
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
-# RUN: not ld.lld %t -o /no/such/file 2>&1 | FileCheck -check-prefix=MISSING %s
+# RUN: not ld.lld %t -o /no/such/file -no-early-path-checks 2>&1 | FileCheck -check-prefix=MISSING %s
 # MISSING: failed to open /no/such/file
 
 # RUN: ld.lld --help 2>&1 | FileCheck -check-prefix=HELP %s
@@ -47,11 +47,11 @@
 # ERR6: -shared and -pie may not be used together
 
 ## "--output=foo" is equivalent to "-o foo".
-# RUN: not ld.lld %t --output=/no/such/file 2>&1 | FileCheck -check-prefix=ERR7 %s
+# RUN: not ld.lld %t --output=/no/such/file -no-early-path-checks 2>&1 | FileCheck -check-prefix=ERR7 %s
 # ERR7: failed to open /no/such/file
 
 ## "-output=foo" is equivalent to "-o utput=foo".
-# RUN: not ld.lld %t -output=/no/such/file 2>&1 | FileCheck -check-prefix=ERR8 %s
+# RUN: not ld.lld %t -output=/no/such/file -no-early-path-checks 2>&1 | FileCheck -check-prefix=ERR8 %s
 # ERR8: failed to open utput=/no/such/file
 
 .globl _start
Index: test/ELF/early-exit-for-bad-paths.s
===================================================================
--- test/ELF/early-exit-for-bad-paths.s
+++ test/ELF/early-exit-for-bad-paths.s
@@ -0,0 +1,43 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+
+# RUN: not ld.lld %t.o -o does_not_exist/output 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OUTPUT,NO-DIR,CHECK
+# RUN: not ld.lld %t.o -o %s/dir_is_a_file 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OUTPUT,DIR-IS-FILE,CHECK
+# RUN: not ld.lld %t.o -o %p 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OUTPUT,PATH-IS-DIR,CHECK
+
+# RUN: not ld.lld %t.o -o %t.elf --Map=does_not_exist/output 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=MAP,NO-DIR,CHECK
+# RUN: not ld.lld %t.o -o %t.elf --Map=%s/dir_is_a_file 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=MAP,DIR-IS-FILE,CHECK
+# RUN: not ld.lld %t.o -o %t.elf --Map=%p 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=MAP,PATH-IS-DIR,CHECK
+
+# RUN: not ld.lld %t.o -o %t.elf -opt-remarks-filename does_not_exist/output 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OPTREMARKS,NO-DIR,CHECK
+# RUN: not ld.lld %t.o -o %t.elf -opt-remarks-filename %s/dir_is_a_file 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OPTREMARKS,DIR-IS-FILE,CHECK
+# RUN: not ld.lld %t.o -o %t.elf -opt-remarks-filename %p 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=OPTREMARKS,PATH-IS-DIR,CHECK
+
+# RUN: not ld.lld %t.o -o %s/do_not_check --no-early-path-checks 2>&1 | \
+# RUN:   FileCheck %s -check-prefixes=NOCHECK
+
+# OUTPUT: error: -o:
+# MAP: error: --Map:
+# OPTREMARKS: error: -opt-remarks-filename:
+
+# NO-DIR-SAME: cannot write to does_not_exist/output
+# DIR-IS-FILE-SAME: cannot write to {{.*}}/dir_is_a_file
+# PATH-IS-DIR-SAME: {{.*}} is a directory
+
+# We should exit before doing the actual link. If an undefined symbol error is
+# discovered we haven't bailed out early as expected.
+# CHECK-NOT: undefined_symbol
+# NOCHECK: undefined symbol 'undefined_symbol'
+
+  .globl _start
+_start:
+  call undefined_symbol
Index: test/ELF/map-file.s
===================================================================
--- test/ELF/map-file.s
+++ test/ELF/map-file.s
@@ -57,6 +57,6 @@
 // CHECK-NEXT: 0000000000000000 000000000000002f     1 .strtab
 // CHECK-NEXT: 0000000000000000 000000000000002f     1         .strtab
 
-// RUN: not ld.lld %t1.o %t2.o %t3.o %t4.a -o %t -Map=/ 2>&1 \
+// RUN: not ld.lld %t1.o %t2.o %t3.o %t4.a -o %t -Map=/ -no-early-path-checks 2>&1 \
 // RUN:  | FileCheck -check-prefix=FAIL %s
 // FAIL: cannot open /