diff --git a/src/Util.cpp b/src/Util.cpp
index fc4e3a77ab4a..86f4747726ff 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -104,6 +104,25 @@ std::wstring from_utf8(const std::string &str) {
     return wstr;
 }
 
+// Prepend \\?\ to the path if it's an absolute drive path and doesn't
+// already have it. This is needed for some Windows APIs that don't
+// support long paths otherwise.
+std::wstring to_long_path(const std::string &str) {
+    std::wstring wstr = from_utf8(str);
+    for (auto &c : wstr) {
+        if (c == L'/') {
+            c = L'\\';
+        }
+    }
+    bool is_absolute_drive_path = wstr.size() >= 2 &&
+                                  ((wstr[0] >= L'A' && wstr[0] <= L'Z') || (wstr[0] >= L'a' && wstr[0] <= L'z')) &&
+                                  wstr[1] == L':';
+    if (is_absolute_drive_path && wstr.rfind(LR"(\\?\)", 0) != 0) {
+        wstr = LR"(\\?\)" + wstr;
+    }
+    return wstr;
+}
+
 }  // namespace
 #endif
 
@@ -316,7 +335,7 @@ std::string strip_namespaces(const std::string &name) {
 
 bool file_exists(const std::string &name) {
 #ifdef _MSC_VER
-    return _access(name.c_str(), 0) == 0;
+    return _waccess(to_long_path(name).c_str(), 0) == 0;
 #else
     return ::access(name.c_str(), F_OK) == 0;
 #endif
@@ -332,7 +351,7 @@ void assert_no_file_exists(const std::string &name) {
 
 void file_unlink(const std::string &name) {
 #ifdef _MSC_VER
-    _unlink(name.c_str());
+    DeleteFileW(to_long_path(name).c_str());
 #else
     ::unlink(name.c_str());
 #endif
@@ -347,7 +366,7 @@ void ensure_no_file_exists(const std::string &name) {
 
 void dir_rmdir(const std::string &name) {
 #ifdef _MSC_VER
-    std::wstring wname = from_utf8(name);
+    std::wstring wname = to_long_path(name);
     internal_assert(RemoveDirectoryW(wname.c_str()))
         << "RemoveDirectoryW() failed to remove " << name << "; error " << GetLastError() << "\n";
 #else
@@ -359,7 +378,7 @@ void dir_rmdir(const std::string &name) {
 FileStat file_stat(const std::string &name) {
 #ifdef _MSC_VER
     struct _stat a;
-    if (_stat(name.c_str(), &a) != 0) {
+    if (_wstat(to_long_path(name).c_str(), &a) != 0) {
         user_error << "Could not stat " << name << "\n";
     }
 #else
@@ -463,7 +482,7 @@ std::string dir_make_temp() {
             name << (int)guid.Data4[i];
         }
         std::string dir = tmp_dir + name.str();
-        std::wstring wdir = from_utf8(dir);
+        std::wstring wdir = to_long_path(dir);
         BOOL success = CreateDirectoryW(wdir.c_str(), nullptr);
         if (success) {
             debug(1) << "temp dir is: " << dir << "\n";
@@ -489,7 +508,11 @@ std::string dir_make_temp() {
 }
 
 std::vector<char> read_entire_file(const std::string &pathname) {
+#ifdef _MSC_VER
+    std::ifstream f(to_long_path(pathname).c_str(), std::ios::in | std::ios::binary);
+#else
     std::ifstream f(pathname, std::ios::in | std::ios::binary);
+#endif
     std::vector<char> result;
 
     f.seekg(0, std::ifstream::end);
@@ -503,7 +526,11 @@ std::vector<char> read_entire_file(const std::string &pathname) {
 }
 
 void write_entire_file(const std::string &pathname, const void *source, size_t source_len) {
+#ifdef _MSC_VER
+    std::ofstream f(to_long_path(pathname).c_str(), std::ios::out | std::ios::binary);
+#else
     std::ofstream f(pathname, std::ios::out | std::ios::binary);
+#endif
 
     f.write(reinterpret_cast<const char *>(source), source_len);
     f.flush();
@@ -536,7 +563,7 @@ int run_process(std::vector<std::string> args, const std::string &stdout_path, c
     int saved_stdout = -1, saved_stderr = -1;
     if (!stdout_path.empty()) {
         saved_stdout = _dup(_fileno(stdout));
-        int fd = _open(stdout_path.c_str(), _O_WRONLY | _O_CREAT | _O_TRUNC | _O_BINARY, _S_IWRITE);
+        int fd = _wopen(to_long_path(stdout_path).c_str(), _O_WRONLY | _O_CREAT | _O_TRUNC | _O_BINARY, _S_IWRITE);
         if (fd == -1) {
             if (saved_stdout != -1) {
                 _close(saved_stdout);
@@ -555,7 +582,7 @@ int run_process(std::vector<std::string> args, const std::string &stdout_path, c
             // writes would clobber each other instead of concatenating.
             _dup2(_fileno(stdout), _fileno(stderr));
         } else {
-            int fd = _open(stderr_path.c_str(), _O_WRONLY | _O_CREAT | _O_TRUNC | _O_BINARY, _S_IWRITE);
+            int fd = _wopen(to_long_path(stderr_path).c_str(), _O_WRONLY | _O_CREAT | _O_TRUNC | _O_BINARY, _S_IWRITE);
             if (fd == -1) {
                 if (saved_stdout != -1) {
                     _dup2(saved_stdout, _fileno(stdout));