Index: llvm/trunk/test/Reduce/remove-funcs.ll
===================================================================
--- llvm/trunk/test/Reduce/remove-funcs.ll
+++ llvm/trunk/test/Reduce/remove-funcs.ll
@@ -1,8 +1,7 @@
 ; Test that llvm-reduce can remove uninteresting functions as well as
 ; their InstCalls.
 ;
-; RUN: llvm-reduce --test %p/Inputs/remove-funcs.py %s
-; RUN: cat reduced.ll | FileCheck %s
+; RUN: llvm-reduce --test %p/Inputs/remove-funcs.py %s -o - | FileCheck %s
 ; REQUIRES: plugins, shell
 
 ; CHECK-NOT: uninteresting1()
Index: llvm/trunk/tools/llvm-reduce/TestRunner.cpp
===================================================================
--- llvm/trunk/tools/llvm-reduce/TestRunner.cpp
+++ llvm/trunk/tools/llvm-reduce/TestRunner.cpp
@@ -49,7 +49,7 @@
   if (Result < 0) {
     Error E = make_error<StringError>("Error running interesting-ness test\n",
                                       inconvertibleErrorCode());
-    outs() << toString(std::move(E));
+    errs() << toString(std::move(E));
     exit(1);
   }
 
Index: llvm/trunk/tools/llvm-reduce/deltas/Delta.h
===================================================================
--- llvm/trunk/tools/llvm-reduce/deltas/Delta.h
+++ llvm/trunk/tools/llvm-reduce/deltas/Delta.h
@@ -36,10 +36,10 @@
   bool contains(unsigned Index) const { return Index >= begin && Index <= end; }
 
   void print() const {
-    outs() << "[" << begin;
+    errs() << "[" << begin;
     if (end - begin != 0)
-      outs() << "," << end;
-    outs() << "]";
+      errs() << "," << end;
+    errs() << "]";
   }
 
   /// Operator when populating CurrentChunks in Generic Delta Pass
Index: llvm/trunk/tools/llvm-reduce/deltas/Delta.cpp
===================================================================
--- llvm/trunk/tools/llvm-reduce/deltas/Delta.cpp
+++ llvm/trunk/tools/llvm-reduce/deltas/Delta.cpp
@@ -50,23 +50,6 @@
   return UniqueFilepath;
 }
 
-/// Prints the Chunk Indexes with the following format: [start, end], if
-/// chunk is at minimum size (1), then it just displays [start].
-static void printChunks(std::vector<Chunk> Chunks, bool Oneline = false) {
-  if (Chunks.empty()) {
-    outs() << "No Chunks";
-    return;
-  }
-
-  for (auto C : Chunks) {
-    if (!Oneline)
-      outs() << '\t';
-    C.print();
-    if (!Oneline)
-      outs() << '\n';
-  }
-}
-
 /// Counts the amount of lines for a given file
 static unsigned getLines(StringRef Filepath) {
   unsigned Lines = 0;
@@ -82,7 +65,7 @@
 /// Splits Chunks in half and prints them.
 /// If unable to split (when chunk size is 1) returns false.
 static bool increaseGranularity(std::vector<Chunk> &Chunks) {
-  outs() << "Increasing granularity...";
+  errs() << "Increasing granularity...";
   std::vector<Chunk> NewChunks;
   bool SplitOne = false;
 
@@ -98,8 +81,12 @@
   }
   if (SplitOne) {
     Chunks = NewChunks;
-    outs() << "Success! New Chunks:\n";
-    printChunks(Chunks);
+    errs() << "Success! New Chunks:\n";
+    for (auto C : Chunks) {
+      errs() << '\t';
+      C.print();
+      errs() << '\n';
+    }
   }
   return SplitOne;
 }
@@ -112,11 +99,11 @@
     std::function<void(const std::vector<Chunk> &, Module *)>
         ExtractChunksFromModule) {
   if (!Targets) {
-    outs() << "\nNothing to reduce\n";
+    errs() << "\nNothing to reduce\n";
     return;
   }
   if (!Test.run(Test.getReducedFilepath())) {
-    outs() << "\nInput isn't interesting! Verify interesting-ness test\n";
+    errs() << "\nInput isn't interesting! Verify interesting-ness test\n";
     exit(1);
   }
 
@@ -125,7 +112,7 @@
   std::unique_ptr<Module> ReducedProgram;
 
   if (!increaseGranularity(Chunks)) {
-    outs() << "\nAlready at minimum size. Cannot reduce anymore.\n";
+    errs() << "\nAlready at minimum size. Cannot reduce anymore.\n";
     return;
   }
 
@@ -149,20 +136,23 @@
       SmallString<128> CurrentFilepath =
           createTmpFile(Clone.get(), Test.getTmpDir());
 
-      outs() << "Testing with: ";
-      printChunks(CurrentChunks, /*Oneline=*/true);
-      outs() << " | " << sys::path::filename(CurrentFilepath);
+      errs() << "Ignoring: ";
+      Chunks[I].print();
+      for (auto C : UninterestingChunks)
+        C.print();
+
+      errs() << " | " << sys::path::filename(CurrentFilepath);
 
       // Current Chunks aren't interesting
       if (!Test.run(CurrentFilepath)) {
-        outs() << "\n";
+        errs() << "\n";
         continue;
       }
 
       UninterestingChunks.insert(Chunks[I]);
       Test.setReducedFilepath(CurrentFilepath);
       ReducedProgram = std::move(Clone);
-      outs() << " **** SUCCESS | lines: " << getLines(CurrentFilepath) << "\n";
+      errs() << " **** SUCCESS | lines: " << getLines(CurrentFilepath) << "\n";
     }
     // Delete uninteresting chunks
     erase_if(Chunks, [&UninterestingChunks](const Chunk &C) {
@@ -174,5 +164,5 @@
   // If we reduced the testcase replace it
   if (ReducedProgram)
     Test.setProgram(std::move(ReducedProgram));
-  outs() << "Couldn't increase anymore.\n";
+  errs() << "Couldn't increase anymore.\n";
 }
\ No newline at end of file
Index: llvm/trunk/tools/llvm-reduce/deltas/ReduceFunctions.cpp
===================================================================
--- llvm/trunk/tools/llvm-reduce/deltas/ReduceFunctions.cpp
+++ llvm/trunk/tools/llvm-reduce/deltas/ReduceFunctions.cpp
@@ -54,19 +54,19 @@
 /// respective name & index
 static unsigned countFunctions(Module *Program) {
   // TODO: Silence index with --quiet flag
-  outs() << "----------------------------\n";
-  outs() << "Function Index Reference:\n";
+  errs() << "----------------------------\n";
+  errs() << "Function Index Reference:\n";
   unsigned FunctionCount = 0;
   for (auto &F : *Program)
-    outs() << "\t" << ++FunctionCount << ": " << F.getName() << "\n";
+    errs() << "\t" << ++FunctionCount << ": " << F.getName() << "\n";
 
-  outs() << "----------------------------\n";
+  errs() << "----------------------------\n";
   return FunctionCount;
 }
 
 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) {
-  outs() << "*** Reducing Functions...\n";
+  errs() << "*** Reducing Functions...\n";
   unsigned Functions = countFunctions(Test.getProgram());
   runDeltaPass(Test, Functions, extractFunctionsFromModule);
-  outs() << "----------------------------\n";
+  errs() << "----------------------------\n";
 }
\ No newline at end of file
Index: llvm/trunk/tools/llvm-reduce/llvm-reduce.cpp
===================================================================
--- llvm/trunk/tools/llvm-reduce/llvm-reduce.cpp
+++ llvm/trunk/tools/llvm-reduce/llvm-reduce.cpp
@@ -89,17 +89,22 @@
   StringRef ReducedFilename = sys::path::filename(Tester.getReducedFilepath());
 
   if (ReducedFilename == sys::path::filename(InputFilename)) {
-    outs() << "\nCouldnt reduce input :/\n";
+    errs() << "\nCouldnt reduce input :/\n";
   } else {
-    if (ReplaceInput) // In-place
-      OutputFilename = InputFilename.c_str();
-    else if (OutputFilename.empty())
-      OutputFilename = "reduced.ll";
-    else
-      OutputFilename += ".ll";
-
-    sys::fs::copy_file(Tester.getReducedFilepath(), OutputFilename);
-    outs() << "\nDone reducing! Reduced IR to file: " << OutputFilename << "\n";
+    // Print reduced file to STDOUT
+    if (OutputFilename == "-")
+      Tester.getProgram()->print(outs(), nullptr);
+    else {
+      if (ReplaceInput) // In-place
+        OutputFilename = InputFilename.c_str();
+      else if (OutputFilename.empty())
+        OutputFilename = "reduced.ll";
+      else
+        OutputFilename += ".ll";
+
+      sys::fs::copy_file(Tester.getReducedFilepath(), OutputFilename);
+      errs() << "\nDone reducing! Reduced testcase: " << OutputFilename << "\n";
+    }
   }
 
   return 0;