diff --git a/llvm/include/llvm/Support/raw_ostream.h b/llvm/include/llvm/Support/raw_ostream.h
--- a/llvm/include/llvm/Support/raw_ostream.h
+++ b/llvm/include/llvm/Support/raw_ostream.h
@@ -412,6 +412,7 @@
   int FD;
   bool ShouldClose;
   bool SupportsSeeking = false;
+  mutable Optional<bool> HasColors;
 
 #ifdef _WIN32
   /// True if this fd refers to a Windows console device. Mintty and other
diff --git a/llvm/lib/Support/raw_ostream.cpp b/llvm/lib/Support/raw_ostream.cpp
--- a/llvm/lib/Support/raw_ostream.cpp
+++ b/llvm/lib/Support/raw_ostream.cpp
@@ -858,7 +858,9 @@
 }
 
 bool raw_fd_ostream::has_colors() const {
-  return sys::Process::FileDescriptorHasColors(FD);
+  if (!HasColors)
+    HasColors = sys::Process::FileDescriptorHasColors(FD);
+  return *HasColors;
 }
 
 Expected<sys::fs::FileLocker> raw_fd_ostream::lock() {