Index: clang-tools-extra/test/clang-tidy/infrastructure/config-file.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/infrastructure/config-file.cpp
@@ -0,0 +1,12 @@
+// REQUIRES: shell
+// RUN: mkdir -p %T/config-file/
+// RUN: cp %s %T/read-file-config/test.cpp
+// RUN: echo 'Checks: "-*,hicpp-uppercase-literal-suffix"' > %T/read-file-config/.clang-tidy
+// RUN: clang-tidy --config-file=%T/read-file-config/.clang-tidy %T/read-file-config/test.cpp | grep "warning: .*\[hicpp-uppercase-literal-suffix\]$"
+
+void f() {
+  unsigned long c = 100ull;
+  int x;
+  x = 1;
+  x = 2;
+}