Index: include/llvm/Support/FileSystem.h
===================================================================
--- include/llvm/Support/FileSystem.h
+++ include/llvm/Support/FileSystem.h
@@ -378,9 +378,7 @@
 ///
 /// @param Path Input path.
 /// @returns True if we can execute it, false otherwise.
-inline bool can_execute(const Twine &Path) {
-  return !access(Path, AccessMode::Execute);
-}
+bool can_execute(const Twine &Path);
 
 /// @brief Can we write this file?
 ///
Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc
+++ lib/Support/Unix/Path.inc
@@ -325,6 +325,10 @@
   return std::error_code();
 }
 
+bool can_execute(const Twine &Path) {
+  return !access(Path, AccessMode::Execute);
+}
+
 bool equivalent(file_status A, file_status B) {
   assert(status_known(A) && status_known(B));
   return A.fs_st_dev == B.fs_st_dev &&
Index: lib/Support/Windows/Path.inc
===================================================================
--- lib/Support/Windows/Path.inc
+++ lib/Support/Windows/Path.inc
@@ -17,6 +17,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/WindowsError.h"
 #include <fcntl.h>
 #include <io.h>
@@ -302,6 +303,21 @@
   return std::error_code();
 }
 
+bool can_execute(const Twine &Path) {
+  SmallVector<StringRef, 12> PathExts;
+  PathExts.push_back("");
+  PathExts.push_back(".exe"); // FIXME: This must be in %PATHEXT%.
+  if (const char *PathExtEnv = std::getenv("PATHEXT"))
+    SplitString(PathExtEnv, PathExts, ";");
+
+  for (StringRef Ext : PathExts) {
+    if (!access(Path + Ext, AccessMode::Execute))
+      return true;
+  }
+
+  return false;
+}
+
 bool equivalent(file_status A, file_status B) {
   assert(status_known(A) && status_known(B));
   return A.FileIndexHigh      == B.FileIndexHigh &&