diff --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -255,6 +255,7 @@
 
 void WebAssemblyTargetInfo::adjust(DiagnosticsEngine &Diags,
                                    LangOptions &Opts) {
+  TargetInfo::adjust(Diags, Opts);
   // If the Atomics feature isn't available, turn off POSIXThreads and
   // ThreadModel, so that we don't predefine _REENTRANT or __STDCPP_THREADS__.
   if (!HasAtomics) {
diff --git a/clang/test/CXX/cpp/cpp.predefined/p1.cpp b/clang/test/CXX/cpp/cpp.predefined/p1.cpp
--- a/clang/test/CXX/cpp/cpp.predefined/p1.cpp
+++ b/clang/test/CXX/cpp/cpp.predefined/p1.cpp
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -std=c++1z %s -verify -triple x86_64-linux-gnu -DALIGN=16
 // RUN: %clang_cc1 -std=c++1z %s -verify -fnew-alignment=2 -DALIGN=2
 // RUN: %clang_cc1 -std=c++1z %s -verify -fnew-alignment=256 -DALIGN=256
+// RUN: %clang_cc1 -std=c++1z %s -verify -triple wasm32-unknown-unknown -fnew-alignment=256 -DALIGN=256
 
 // expected-no-diagnostics