diff --git a/utils/lit/lit/main.py b/utils/lit/lit/main.py
index 20b001e..bae6d91 100755
--- a/utils/lit/lit/main.py
+++ b/utils/lit/lit/main.py
@@ -321,10 +321,6 @@
     debug_group.add_argument("--show-tests", dest="showTests",
                       help="Show all discovered tests",
                       action="store_true", default=False)
-    debug_group.add_argument("--single-process", dest="singleProcess",
-                      help="Don't run tests in parallel.  Intended for debugging "
-                      "single test failures",
-                      action="store_true", default=False)
 
     opts = parser.parse_args()
     args = opts.test_paths
@@ -336,7 +332,9 @@
     if not args:
         parser.error('No inputs specified')
 
-    if opts.numThreads is not None and opts.numThreads <= 0:
+    if opts.numThreads is None:
+        opts.numThreads = lit.util.detectCPUs()
+    elif opts.numThreads <= 0:
         parser.error("Option '--threads' or '-j' requires positive integer")
 
     if opts.maxFailures is not None and opts.maxFailures <= 0:
@@ -480,12 +478,6 @@
     if opts.maxTests is not None:
         run.tests = run.tests[:opts.maxTests]
 
-    # Determine number of workers to use.
-    if opts.singleProcess:
-        opts.numThreads = 1
-    elif opts.numThreads is None:
-        opts.numThreads = lit.util.detectCPUs()
-
     # Don't create more threads than tests.
     opts.numThreads = min(len(run.tests), opts.numThreads)
 
diff --git a/utils/lit/tests/discovery.py b/utils/lit/tests/discovery.py
index dbabeb3..9f09470 100644
--- a/utils/lit/tests/discovery.py
+++ b/utils/lit/tests/discovery.py
@@ -29,7 +29,7 @@
 # RUN: %{python} %{inputs}/config-map-discovery/driver.py \
 # RUN:           %{inputs}/config-map-discovery/main-config/lit.cfg \
 # RUN:           %{inputs}/config-map-discovery/lit.alt.cfg \
-# RUN:           --single-process --debug --show-tests --show-suites > %t.out 2> %t.err
+# RUN:           --threads=1 --debug --show-tests --show-suites > %t.out 2> %t.err
 # RUN: FileCheck --check-prefix=CHECK-CONFIG-MAP-OUT < %t.out %s
 # RUN: FileCheck --check-prefix=CHECK-CONFIG-MAP-ERR < %t.err %s