diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2085,7 +2085,7 @@
 
   if (IsCLMode()) {
     if (!llvm::sys::path::is_absolute(Twine(Value)) &&
-        llvm::sys::Process::FindInEnvPath("LIB", Value))
+        llvm::sys::Process::FindInEnvPath("LIB", Value, ';'))
       return true;
 
     if (Args.hasArg(options::OPT__SLASH_link) && Ty == types::TY_Object) {
diff --git a/clang/test/Driver/cl-inputs.c b/clang/test/Driver/cl-inputs.c
--- a/clang/test/Driver/cl-inputs.c
+++ b/clang/test/Driver/cl-inputs.c
@@ -32,7 +32,9 @@
 // WARN-NOT: note
 
 // MSYS2_ARG_CONV_EXCL tells MSYS2 to skip conversion of the specified argument.
-// RUN: env LIB=%S/Inputs/cl-libs MSYS2_ARG_CONV_EXCL="/TP;/c" %clang_cl /c /TP cl-test.lib -### 2>&1 | FileCheck -check-prefix=TPlib %s
+// Add a dummy "other" entry to the path as well, to check that it's split
+// around semicolons even on unix.
+// RUN: env LIB="other;%S/Inputs/cl-libs" MSYS2_ARG_CONV_EXCL="/TP;/c" %clang_cl /c /TP cl-test.lib -### 2>&1 | FileCheck -check-prefix=TPlib %s
 // TPlib: warning: cl-test.lib: 'linker' input unused
 // TPlib: warning: argument unused during compilation: '/TP'
 // TPlib-NOT: cl-test.lib
diff --git a/llvm/include/llvm/Support/Process.h b/llvm/include/llvm/Support/Process.h
--- a/llvm/include/llvm/Support/Process.h
+++ b/llvm/include/llvm/Support/Process.h
@@ -29,6 +29,7 @@
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/Program.h"
 #include <system_error>
 
 namespace llvm {
@@ -107,10 +108,12 @@
   /// considered.
   static Optional<std::string> FindInEnvPath(StringRef EnvName,
                                              StringRef FileName,
-                                             ArrayRef<std::string> IgnoreList);
+                                             ArrayRef<std::string> IgnoreList,
+                                             char Separator = EnvPathSeparator);
 
   static Optional<std::string> FindInEnvPath(StringRef EnvName,
-                                             StringRef FileName);
+                                             StringRef FileName,
+                                             char Separator = EnvPathSeparator);
 
   // This functions ensures that the standard file descriptors (input, output,
   // and error) are properly mapped to a file descriptor before we use any of
diff --git a/llvm/lib/Support/Process.cpp b/llvm/lib/Support/Process.cpp
--- a/llvm/lib/Support/Process.cpp
+++ b/llvm/lib/Support/Process.cpp
@@ -28,21 +28,22 @@
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
-Optional<std::string> Process::FindInEnvPath(StringRef EnvName,
-                                             StringRef FileName) {
-  return FindInEnvPath(EnvName, FileName, {});
+Optional<std::string>
+Process::FindInEnvPath(StringRef EnvName, StringRef FileName, char Separator) {
+  return FindInEnvPath(EnvName, FileName, {}, Separator);
 }
 
 Optional<std::string> Process::FindInEnvPath(StringRef EnvName,
                                              StringRef FileName,
-                                             ArrayRef<std::string> IgnoreList) {
+                                             ArrayRef<std::string> IgnoreList,
+                                             char Separator) {
   assert(!path::is_absolute(FileName));
   Optional<std::string> FoundPath;
   Optional<std::string> OptPath = Process::GetEnv(EnvName);
   if (!OptPath.hasValue())
     return FoundPath;
 
-  const char EnvPathSeparatorStr[] = {EnvPathSeparator, '\0'};
+  const char EnvPathSeparatorStr[] = {Separator, '\0'};
   SmallVector<StringRef, 8> Dirs;
   SplitString(OptPath.getValue(), Dirs, EnvPathSeparatorStr);