diff --git a/lib/IRGen/GenType.cpp b/lib/IRGen/GenType.cpp
index 7c8423d1f357b..b518a5e7cd237 100644
--- a/lib/IRGen/GenType.cpp
+++ b/lib/IRGen/GenType.cpp
@@ -1380,8 +1380,9 @@ TypeConverter::TypeConverter(IRGenModule &IGM)
   }
 
   bool error = readLegacyTypeInfo(*fs, path);
-  if (error)
-    llvm::report_fatal_error("Cannot read '" + path + "'");
+// avoids error: "<unknown>:1:1: Cannot read '/usr/lib/swift/layouts-x86_64.yaml'"
+//  if (error)
+//    llvm::report_fatal_error("Cannot read '" + path + "'");
 }
 
 TypeConverter::~TypeConverter() {
diff --git a/lib/Serialization/Deserialization.cpp b/lib/Serialization/Deserialization.cpp
index 028919584dfd6..05e288bd9f830 100644
--- a/lib/Serialization/Deserialization.cpp
+++ b/lib/Serialization/Deserialization.cpp
@@ -5008,7 +5008,14 @@ class TypeDeserializer {
       MF.fatal();
 
     const clang::Type *clangFunctionType = nullptr;
-    if (clangTypeID) {
+    // avoids: "error: Segmentation fault: 11" (SR-12831)
+    // during "merge module" containing the following code:
+    /*
+    static var onEntry: @convention(c) (_ swizzle: Swizzle, _ returnAddress: UnsafeRawPointer,
+        _ stackPointer: UnsafeMutablePointer<UInt64>) -> IMP? = {
+            (swizzle, returnAddress, stackPointer) -> IMP? in
+     */
+    if (clangTypeID && false) {
       auto loadedClangType = MF.getClangType(clangTypeID);
       if (!loadedClangType)
         return loadedClangType.takeError();