diff --git a/Dockerfile.dev b/Dockerfile.dev
index b553fc5..2738fe7 100644
--- a/Dockerfile.dev
+++ b/Dockerfile.dev
@@ -53,7 +53,7 @@ RUN ./build-mingw-w64-libraries.sh $TOOLCHAIN_PREFIX
 # Build C test applications
 ENV PATH=$TOOLCHAIN_PREFIX/bin:$PATH
 
-COPY test/*.c test/*.h ./test/
+COPY test/*.c test/*.h test/*.idl ./test/
 RUN cd test && \
     for arch in $TOOLCHAIN_ARCHS; do \
         mkdir -p $arch && \
@@ -66,6 +66,11 @@ RUN cd test && \
         for test in autoimport-main; do \
             $arch-w64-mingw32-clang $test.c -o $arch/$test.exe -L$arch -l${test%-main}-lib || exit 1; \
         done; \
+        for test in idltest; do \
+            # The IDL output isn't arch specific, but test each arch frontend \
+            $arch-w64-mingw32-widl $test.idl -h -o $arch/$test.h && \
+            $arch-w64-mingw32-clang $test.c -I$arch -o $arch/$test.exe -lole32 || exit 1; \
+        done; \
     done
 
 # Build libunwind/libcxxabi/libcxx
diff --git a/run-tests.sh b/run-tests.sh
index 3e6f216..21f246b 100755
--- a/run-tests.sh
+++ b/run-tests.sh
@@ -70,6 +70,7 @@ TESTS_SSP="stacksmash"
 TESTS_ASAN="stacksmash"
 TESTS_UBSAN="ubsan"
 TESTS_UWP="uwp-error"
+TESTS_IDL="idltest"
 TESTS_OTHER_TARGETS="hello"
 for arch in $ARCHS; do
     case $arch in
@@ -141,6 +142,13 @@ for arch in $ARCHS; do
     for test in $TESTS_SSP; do
         $arch-w64-mingw32-clang $test.c -o $TEST_DIR/$test.exe -fstack-protector-strong
     done
+    for test in $TESTS_IDL; do
+        # This is primary a build-only test, so no need to execute it.
+        # The IDL output isn't arch specific, but we want to test the
+        # individual widl frontends.
+        $arch-w64-mingw32-widl $test.idl -h -o $TEST_DIR/$test.h
+        $arch-w64-mingw32-clang $test.c -I$TEST_DIR -o $TEST_DIR/$test.exe -lole32
+    done
     for target_os in $TARGET_OSES; do
         for test in $TESTS_UWP; do
             set +e
diff --git a/test/idltest.c b/test/idltest.c
new file mode 100644
index 0000000..6bf0a14
--- /dev/null
+++ b/test/idltest.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2020 Martin Storsjo
+ *
+ * This file is part of llvm-mingw.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <windows.h>
+#include <initguid.h>
+#define COBJMACROS
+#include "idltest.h"
+
+int main(int argc, char *argv[]) {
+    if (argc <= 1)
+        return 0;
+
+    ITestClass *obj;
+    CoInitializeEx(NULL, COINIT_MULTITHREADED);
+    if (CoCreateInstance(&CLSID_TestClassImplementation, 0, CLSCTX_INPROC, &IID_ITestClass, (void*)&obj))
+        return 0;
+    ITestClass_DoSomething(obj, 0);
+    ITestClass_Release(obj);
+    return 0;
+}
diff --git a/test/idltest.idl b/test/idltest.idl
new file mode 100644
index 0000000..883dd38
--- /dev/null
+++ b/test/idltest.idl
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2020 Martin Storsjo
+ *
+ * This file is part of llvm-mingw.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+import "unknwn.idl";
+
+[
+    uuid(73ad110f-de60-4d7a-899a-58f2afc033a7),
+]
+interface ITestClass : IUnknown
+{
+    HRESULT DoSomething([in] ULONG param);
+}
+
+cpp_quote("DEFINE_GUID(CLSID_TestClassImplementation, 0x5247bb7c,0x51d6,0x42ce,0xa3,0xd1,0x1c,0xe9,0x65,0xf6,0x93,0x72);")