diff --git a/emscripten-version.txt b/emscripten-version.txt
index 3166fbaa77f..226e95b7c3c 100644
--- a/emscripten-version.txt
+++ b/emscripten-version.txt
@@ -1,2 +1,2 @@
-1.14.1
+1.15.0
 
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index 45d313b2edd..b56b42c798e 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -269,6 +269,7 @@ class EmscriptenTargetInfo : public OSTargetInfo<Target> {
     // handled outside of clang. TODO: Handling this within clang may be
     // beneficial.
     this->UserLabelPrefix = "";
+    this->MaxAtomicPromoteWidth = this->MaxAtomicInlineWidth = 32;
   }
 };