diff --git a/test/Reduce/remove-args.ll b/test/Reduce/remove-args.ll
index 4823f751923..161a6fd3731 100644
--- a/test/Reduce/remove-args.ll
+++ b/test/Reduce/remove-args.ll
@@ -1,16 +1,7 @@
 ; Test that llvm-reduce can remove uninteresting function arguments from function definitions as well as their calls.
 ;
-; RUN: rm -rf %t
-; RUN: mkdir %t
-; get the python path from lit
-; RUN: echo "#!" %python > %t/test.py
-; then include the rest of the test script
-; RUN: cat %p/Inputs/remove-args.py >> %t/test.py
-; RUN: chmod +x %t/test.py
-
-; RUN: llvm-reduce --test %t/test.py %s -o %t/out.ll
-; RUN: cat %t/out.ll | FileCheck -implicit-check-not=uninteresting %s
-; REQUIRES: shell
+; RUN: llvm-reduce --test %python --test-arg %p/Inputs/remove-args.py %s -o %t
+; RUN: cat %t | FileCheck -implicit-check-not=uninteresting %s
 
 ; CHECK: @interesting(i32 %interesting)
 define void @interesting(i32 %uninteresting1, i32 %interesting, i32 %uninteresting2) {
diff --git a/test/Reduce/remove-funcs.ll b/test/Reduce/remove-funcs.ll
index 6b3c86bea87..59ffd849193 100644
--- a/test/Reduce/remove-funcs.ll
+++ b/test/Reduce/remove-funcs.ll
@@ -1,17 +1,8 @@
 ; Test that llvm-reduce can remove uninteresting functions as well as
 ; their InstCalls.
 ;
-; RUN: rm -rf %t
-; RUN: mkdir %t
-; get the python path from lit
-; RUN: echo "#!" %python > %t/test.py
-; then include the rest of the test script
-; RUN: cat %p/Inputs/remove-funcs.py >> %t/test.py
-; RUN: chmod +x %t/test.py
-
-; RUN: llvm-reduce --test %t/test.py %s -o %t/out.ll
-; RUN: cat %t/out.ll | FileCheck -implicit-check-not=uninteresting %s
-; REQUIRES: shell
+; RUN: llvm-reduce --test %python --test-arg %p/Inputs/remove-funcs.py %s -o %t
+; RUN: cat %t | FileCheck -implicit-check-not=uninteresting %s
 
 define i32 @uninteresting1() {
 entry:
diff --git a/test/Reduce/remove-global-vars.ll b/test/Reduce/remove-global-vars.ll
index 900774762c1..b876acd1b8f 100644
--- a/test/Reduce/remove-global-vars.ll
+++ b/test/Reduce/remove-global-vars.ll
@@ -1,17 +1,8 @@
 ; Test that llvm-reduce can remove uninteresting Global Variables as well as
 ; their direct uses (which in turn are replaced with 'undef').
 ;
-; RUN: rm -rf %t
-; RUN: mkdir %t
-; get the python path from lit
-; RUN: echo "#!" %python > %t/test.py
-; then include the rest of the test script
-; RUN: cat %p/Inputs/remove-global-vars.py >> %t/test.py
-; RUN: chmod +x %t/test.py
-
-; RUN: llvm-reduce --test %t/test.py %s -o %t/out.ll
-; RUN: cat %t/out.ll | FileCheck -implicit-check-not=uninteresting %s
-; REQUIRES: shell
+; RUN: llvm-reduce --test %python --test-arg %p/Inputs/remove-global-vars.py %s -o %t
+; RUN: cat %t | FileCheck -implicit-check-not=uninteresting %s
 
 ; CHECK: @interesting = global
 @interesting = global i32 0, align 4
diff --git a/test/Reduce/remove-metadata.ll b/test/Reduce/remove-metadata.ll
index b887737f3b3..51a50ca20a9 100644
--- a/test/Reduce/remove-metadata.ll
+++ b/test/Reduce/remove-metadata.ll
@@ -1,17 +1,8 @@
 ; Test that llvm-reduce can remove uninteresting metadata from an IR file.
 ; The Metadata pass erases named & unnamed metadata nodes.
 ;
-; RUN: rm -rf %t
-; RUN: mkdir %t
-; get the python path from lit
-; RUN: echo "#!" %python > %t/test.py
-; then include the rest of the test script
-; RUN: cat %p/Inputs/remove-metadata.py >> %t/test.py
-; RUN: chmod +x %t/test.py
-
-; RUN: llvm-reduce --test %t/test.py %s -o %t/out.ll
-; RUN: cat %t/out.ll | FileCheck -implicit-check-not=! %s
-; REQUIRES: shell
+; RUN: llvm-reduce --test %python --test-arg %p/Inputs/remove-metadata.py %s -o %t
+; RUN: cat %t | FileCheck -implicit-check-not=! %s
 
 @global = global i32 0, !dbg !0
 
diff --git a/tools/llvm-reduce/TestRunner.cpp b/tools/llvm-reduce/TestRunner.cpp
index 50b277b6f0e..62600392527 100644
--- a/tools/llvm-reduce/TestRunner.cpp
+++ b/tools/llvm-reduce/TestRunner.cpp
@@ -36,16 +36,16 @@ TestRunner::TestRunner(StringRef TestName, std::vector<std::string> TestArgs)
 int TestRunner::run(StringRef Filename) {
   std::vector<StringRef> ProgramArgs;
   ProgramArgs.push_back(TestName);
+
+  for (const auto &Arg : TestArgs)
+    ProgramArgs.push_back(Arg);
+
   ProgramArgs.push_back(Filename);
 
-  for (auto Arg : TestArgs)
-    ProgramArgs.push_back(Arg.c_str());
-
-  Optional<StringRef> Redirects[3]; // STDIN, STDOUT, STDERR
   std::string ErrMsg;
-  int Result =
-      sys::ExecuteAndWait(TestName, ProgramArgs, None, Redirects,
-                          /*SecondsToWait=*/0, /*MemoryLimit=*/0, &ErrMsg);
+  int Result = sys::ExecuteAndWait(
+      TestName, ProgramArgs, /*Env=*/None, /*Redirects=*/None,
+      /*SecondsToWait=*/0, /*MemoryLimit=*/0, &ErrMsg);
 
   if (Result < 0) {
     Error E = make_error<StringError>("Error running interesting-ness test: " +