diff --git a/llvm/utils/lit/lit/builtin_commands/diff.py b/llvm/utils/lit/lit/builtin_commands/diff.py
index f2b5869b35889..f0c51fec9e09b 100644
--- a/llvm/utils/lit/lit/builtin_commands/diff.py
+++ b/llvm/utils/lit/lit/builtin_commands/diff.py
@@ -219,7 +219,7 @@ def main(argv):
 
     args = argv[1:]
     try:
-        opts, args = getopt.gnu_getopt(args, "wbuI:U:r", ["strip-trailing-cr"])
+        opts, args = getopt.gnu_getopt(args, "wcbuI:U:r", ["strip-trailing-cr"])
     except getopt.GetoptError as err:
         sys.stderr.write("Unsupported: 'diff': %s\n" % str(err))
         sys.exit(1)
@@ -249,6 +249,8 @@ def main(argv):
             flags.recursive_diff = True
         elif o == "--strip-trailing-cr":
             flags.strip_trailing_cr = True
+        elif o == "-c":
+            continue
         else:
             assert False, "unhandled option"
 
diff --git a/llvm/utils/lit/tests/Inputs/shtest-shell/diff-c.txt b/llvm/utils/lit/tests/Inputs/shtest-shell/diff-c.txt
new file mode 100644
index 0000000000000..3e76d8d0d7101
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/shtest-shell/diff-c.txt
@@ -0,0 +1,14 @@
+# Check that the -c option for the internal diff implementation works.
+
+# RUN: echo 1 > %t.foo
+# RUN: echo 2 >> %t.foo
+# RUN: echo 3 >> %t.foo
+# RUN: echo 4 >> %t.foo
+# RUN: echo 5 >> %t.foo
+
+# RUN: echo 1 > %t.bar
+# RUN: echo 2 >> %t.bar
+# RUN: echo 4 >> %t.bar
+# RUN: echo 5 >> %t.bar
+
+# RUN: diff -c %t.foo %t.bar
diff --git a/llvm/utils/lit/tests/shtest-shell.py b/llvm/utils/lit/tests/shtest-shell.py
index 8f2b865f333a5..d99df45a7f363 100644
--- a/llvm/utils/lit/tests/shtest-shell.py
+++ b/llvm/utils/lit/tests/shtest-shell.py
@@ -44,6 +44,23 @@
 # CHECK-NEXT: # error: command failed with exit status: 1
 #      CHECK: ***
 
+#      CHECK: FAIL: shtest-shell :: diff-c.txt
+#      CHECK: *** TEST 'shtest-shell :: diff-c.txt' FAILED ***
+#      CHECK: diff -c {{[^"]*}}.foo {{[^"]*}}.bar
+#      CHECK: # .---command stdout{{-*}}
+# CHECK-NEXT: # | *** {{[^"]*}}.foo
+# CHECK-NEXT: # | --- {{[^"]*}}.bar
+# CHECK-NEXT: # | ***************
+# CHECK-NEXT: # | *** 1,5 ****
+# CHECK-NEXT: # |   1
+# CHECK-NEXT: # |   2
+# CHECK-NEXT: # | - 3
+# CHECK-NEXT: # |   4
+# CHECK-NEXT: # |   5
+# CHECK-NEXT: # | --- 1,4 ----
+# CHECK-NEXT: # `---{{-*}}
+# CHECK-NEXT: # error: command failed with exit status: 1
+#      CHECK: ***
 
 # CHECK: FAIL: shtest-shell :: diff-encodings.txt
 # CHECK: *** TEST 'shtest-shell :: diff-encodings.txt' FAILED ***
@@ -635,4 +652,4 @@
 
 # CHECK: PASS: shtest-shell :: valid-shell.txt
 # CHECK: Unresolved Tests (1)
-# CHECK: Failed Tests (36)
+# CHECK: Failed Tests (37)