diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -984,6 +984,7 @@
     // Emscripten's ABI is unstable and we may change this back to 128 to match
     // the WebAssembly default in the future.
     this->LongDoubleAlign = 64;
+    this->SuitableAlign = 64;
   }
 };
 
diff --git a/clang/test/Preprocessor/init.c b/clang/test/Preprocessor/init.c
--- a/clang/test/Preprocessor/init.c
+++ b/clang/test/Preprocessor/init.c
@@ -1500,10 +1500,10 @@
 //
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-unknown-unknown \
 // RUN:   < /dev/null \
-// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32 %s
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32,WEBASSEMBLY-DEFAULT %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm64-unknown-unknown \
 // RUN:   < /dev/null \
-// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64 %s
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,WEBASSEMBLY-DEFAULT %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-emscripten \
 // RUN:   < /dev/null \
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32,EMSCRIPTEN %s
@@ -1515,10 +1515,10 @@
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,EMSCRIPTEN %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-wasi \
 // RUN:   < /dev/null \
-// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32,WEBASSEMBLY-WASI %s
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32,WEBASSEMBLY-DEFAULT,WEBASSEMBLY-WASI %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm64-wasi \
 // RUN:   < /dev/null \
-// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,WEBASSEMBLY-WASI %s
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,WEBASSEMBLY-DEFAULT,WEBASSEMBLY-WASI %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-unknown-unknown -x c++ \
 // RUN:   < /dev/null \
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY-CXX %s
@@ -1537,7 +1537,8 @@
 // WEBASSEMBLY-NEXT:#define __ATOMIC_RELAXED 0
 // WEBASSEMBLY-NEXT:#define __ATOMIC_RELEASE 3
 // WEBASSEMBLY-NEXT:#define __ATOMIC_SEQ_CST 5
-// WEBASSEMBLY-NEXT:#define __BIGGEST_ALIGNMENT__ 16
+// EMSCRIPTEN-NEXT:#define __BIGGEST_ALIGNMENT__ 8
+// WEBASSEMBLY-DEFAULT-NEXT:#define __BIGGEST_ALIGNMENT__ 16
 // WEBASSEMBLY-NEXT:#define __BITINT_MAXWIDTH__ 128
 // WEBASSEMBLY-NEXT:#define __BOOL_WIDTH__ 8
 // WEBASSEMBLY-NEXT:#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__