diff --git a/clang/include/clang/AST/DeclObjC.h b/clang/include/clang/AST/DeclObjC.h
--- a/clang/include/clang/AST/DeclObjC.h
+++ b/clang/include/clang/AST/DeclObjC.h
@@ -190,13 +190,20 @@
     return getSelLocsKind() != SelLoc_NonStandard;
   }
 
+  size_t getStoredSelLocsOffset() const {
+    return llvm::alignTo<alignof(SourceLocation)>(sizeof(ParmVarDecl *) *
+                                                  NumParams);
+  }
+
   /// Get a pointer to the stored selector identifiers locations array.
   /// No locations will be stored if HasStandardSelLocs is true.
   SourceLocation *getStoredSelLocs() {
-    return reinterpret_cast<SourceLocation *>(getParams() + NumParams);
+    return reinterpret_cast<SourceLocation *>(
+        reinterpret_cast<char *>(ParamsAndSelLocs) + getStoredSelLocsOffset());
   }
   const SourceLocation *getStoredSelLocs() const {
-    return reinterpret_cast<const SourceLocation *>(getParams() + NumParams);
+    return reinterpret_cast<SourceLocation *>(
+        reinterpret_cast<char *>(ParamsAndSelLocs) + getStoredSelLocsOffset());
   }
 
   /// Get a pointer to the stored selector identifiers locations array.
diff --git a/clang/lib/AST/DeclObjC.cpp b/clang/lib/AST/DeclObjC.cpp
--- a/clang/lib/AST/DeclObjC.cpp
+++ b/clang/lib/AST/DeclObjC.cpp
@@ -28,6 +28,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
@@ -874,11 +875,8 @@
   if (Params.empty() && SelLocs.empty())
     return;
 
-  static_assert(alignof(ParmVarDecl *) >= alignof(SourceLocation),
-                "Alignment not sufficient for SourceLocation");
-
-  unsigned Size = sizeof(ParmVarDecl *) * NumParams +
-                  sizeof(SourceLocation) * SelLocs.size();
+  unsigned Size =
+      getStoredSelLocsOffset() + sizeof(SourceLocation) * SelLocs.size();
   ParamsAndSelLocs = C.Allocate(Size);
   std::copy(Params.begin(), Params.end(), getParams());
   std::copy(SelLocs.begin(), SelLocs.end(), getStoredSelLocs());