diff --git a/llvm/tools/llvm-reduce/TestRunner.cpp b/llvm/tools/llvm-reduce/TestRunner.cpp
--- a/llvm/tools/llvm-reduce/TestRunner.cpp
+++ b/llvm/tools/llvm-reduce/TestRunner.cpp
@@ -97,7 +97,9 @@
 
 void TestRunner::writeOutput(StringRef Message) {
   std::error_code EC;
-  raw_fd_ostream Out(OutputFilename, EC);
+  raw_fd_ostream Out(OutputFilename, EC,
+                     EmitBitcode && !Program->isMIR() ? sys::fs::OF_None
+                                                      : sys::fs::OF_Text);
   if (EC) {
     errs() << "Error opening output file: " << EC.message() << "!\n";
     exit(1);
diff --git a/llvm/tools/llvm-reduce/deltas/Delta.cpp b/llvm/tools/llvm-reduce/deltas/Delta.cpp
--- a/llvm/tools/llvm-reduce/deltas/Delta.cpp
+++ b/llvm/tools/llvm-reduce/deltas/Delta.cpp
@@ -74,7 +74,8 @@
   int FD;
   std::error_code EC = sys::fs::createTemporaryFile(
       "llvm-reduce", M.isMIR() ? "mir" : (UseBitcode ? "bc" : "ll"), FD,
-      CurrentFilepath);
+      CurrentFilepath,
+      UseBitcode && !M.isMIR() ? sys::fs::OF_None : sys::fs::OF_Text);
   if (EC) {
     errs() << "Error making unique filename: " << EC.message() << "!\n";
     exit(1);