diff --git a/llvm/utils/lit/lit/main.py b/llvm/utils/lit/lit/main.py
--- a/llvm/utils/lit/lit/main.py
+++ b/llvm/utils/lit/lit/main.py
@@ -252,29 +252,34 @@
     lit.util.printHistogram(test_times, title='Tests')
 
 
+def add_result_category(result_code, label):
+    assert isinstance(result_code, lit.Test.ResultCode)
+    category = (result_code, "%s Tests" % label, label)
+    result_codes.append(category)
+
+
 # Status code, summary label, group label
-failure_codes = [
+result_codes = [
+    # Passes
+    (lit.Test.SKIPPED,     'Skipped Tests',       'Skipped'),
+    (lit.Test.UNSUPPORTED, 'Unsupported Tests',   'Unsupported'),
+    (lit.Test.PASS,        'Expected Passes',     ''),
+    (lit.Test.FLAKYPASS,   'Passes With Retry',   ''),
+    (lit.Test.XFAIL,       'Expected Failures',   'Expected Failing'),
+    # Failures
     (lit.Test.UNRESOLVED,  'Unresolved Tests',    'Unresolved'),
     (lit.Test.TIMEOUT,     'Individual Timeouts', 'Timed Out'),
     (lit.Test.FAIL,        'Unexpected Failures', 'Failing'),
     (lit.Test.XPASS,       'Unexpected Passes',   'Unexpected Passing')
 ]
 
-all_codes = [
-    (lit.Test.SKIPPED,     'Skipped Tests',     'Skipped'),
-    (lit.Test.UNSUPPORTED, 'Unsupported Tests', 'Unsupported'),
-    (lit.Test.PASS,        'Expected Passes',   ''),
-    (lit.Test.FLAKYPASS,   'Passes With Retry', ''),
-    (lit.Test.XFAIL,       'Expected Failures', 'Expected Failing'),
-] + failure_codes
-
 
 def print_results(tests, elapsed, opts):
-    tests_by_code = {code: [] for (code, _, _) in all_codes}
+    tests_by_code = {code: [] for (code, _, _) in result_codes}
     for test in tests:
         tests_by_code[test.result.code].append(test)
 
-    for (code, _, group_label) in all_codes:
+    for (code, _, group_label) in result_codes:
         print_group(code, group_label, tests_by_code[code], opts)
 
     print_summary(tests_by_code, opts.quiet, elapsed)
@@ -300,7 +305,7 @@
     if not quiet:
         print('\nTesting Time: %.2fs' % elapsed)
 
-    codes = failure_codes if quiet else all_codes
+    codes = [c for c in result_codes if not quiet or c.isFailure]
     groups = [(label, len(tests_by_code[code])) for code, label, _ in codes]
     groups = [(label, count) for label, count in groups if count]
     if not groups:
diff --git a/llvm/utils/lit/tests/Inputs/custom-result-category/format.py b/llvm/utils/lit/tests/Inputs/custom-result-category/format.py
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/custom-result-category/format.py
@@ -0,0 +1,18 @@
+import lit
+import lit.formats
+
+CUSTOM_PASS = lit.Test.ResultCode('CUSTOM_PASS', False)
+CUSTOM_FAILURE = lit.Test.ResultCode('CUSTOM_FAILURE', True)
+
+lit.main.add_result_category(CUSTOM_PASS, "My Passed")
+lit.main.add_result_category(CUSTOM_FAILURE, "My Failed")
+
+
+class MyFormat(lit.formats.ShTest):
+    def execute(self, test, lit_config):
+        result = super(MyFormat, self).execute(test, lit_config)
+        if result.code.isFailure:
+            result.code = CUSTOM_FAILURE
+        else:
+            result.code = CUSTOM_PASS
+        return result
diff --git a/llvm/utils/lit/tests/Inputs/custom-result-category/lit.cfg b/llvm/utils/lit/tests/Inputs/custom-result-category/lit.cfg
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/custom-result-category/lit.cfg
@@ -0,0 +1,10 @@
+import lit
+import site
+site.addsitedir(os.path.dirname(__file__))
+import format
+
+config.name = 'custom-result-category'
+config.suffixes = ['.txt']
+config.test_format = format.MyFormat()
+config.test_source_root = None
+config.test_exec_root = None
diff --git a/llvm/utils/lit/tests/Inputs/custom-result-category/test1.txt b/llvm/utils/lit/tests/Inputs/custom-result-category/test1.txt
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/custom-result-category/test1.txt
@@ -0,0 +1 @@
+# RUN: true
diff --git a/llvm/utils/lit/tests/Inputs/custom-result-category/test2.txt b/llvm/utils/lit/tests/Inputs/custom-result-category/test2.txt
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/custom-result-category/test2.txt
@@ -0,0 +1 @@
+# RUN: false
diff --git a/llvm/utils/lit/tests/Inputs/shtest-inject/lit.cfg b/llvm/utils/lit/tests/Inputs/shtest-inject/lit.cfg
--- a/llvm/utils/lit/tests/Inputs/shtest-inject/lit.cfg
+++ b/llvm/utils/lit/tests/Inputs/shtest-inject/lit.cfg
@@ -3,7 +3,7 @@
 preamble_commands = [
     'echo "THIS WAS"',
     'echo "INJECTED"'
-];
+]
 
 config.name = 'shtest-inject'
 config.suffixes = ['.txt']
diff --git a/llvm/utils/lit/tests/custom-result-category.py b/llvm/utils/lit/tests/custom-result-category.py
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/custom-result-category.py
@@ -0,0 +1,13 @@
+# Test lit.main.add_result_category() extension API.
+
+# RUN: not %{lit} -j 1 %{inputs}/custom-result-category | FileCheck %s
+
+# CHECK: CUSTOM_PASS: custom-result-category :: test1.txt
+# CHECK: CUSTOM_FAILURE: custom-result-category :: test2.txt
+
+# TODO(yln): Passing tests shouldn't be printed by default.
+# CHECK: My Passed Tests (1)
+# CHECK: My Failed Tests (1)
+
+# CHECK: My Passed Tests: 1
+# CHECK: My Failed Tests: 1