diff --git a/clang/include/clang/AST/Mangle.h b/clang/include/clang/AST/Mangle.h
--- a/clang/include/clang/AST/Mangle.h
+++ b/clang/include/clang/AST/Mangle.h
@@ -56,7 +56,7 @@
 
   llvm::DenseMap<const BlockDecl*, unsigned> GlobalBlockIds;
   llvm::DenseMap<const BlockDecl*, unsigned> LocalBlockIds;
-  llvm::DenseMap<const TagDecl*, uint64_t> AnonStructIds;
+  llvm::DenseMap<const NamedDecl*, uint64_t> AnonStructIds;
 
 public:
   ManglerKind getKind() const { return Kind; }
@@ -82,9 +82,9 @@
     return Result.first->second;
   }
 
-  uint64_t getAnonymousStructId(const TagDecl *TD) {
-    std::pair<llvm::DenseMap<const TagDecl *, uint64_t>::iterator, bool>
-        Result = AnonStructIds.insert(std::make_pair(TD, AnonStructIds.size()));
+  uint64_t getAnonymousStructId(const NamedDecl *D) {
+    std::pair<llvm::DenseMap<const NamedDecl *, uint64_t>::iterator, bool>
+        Result = AnonStructIds.insert(std::make_pair(D, AnonStructIds.size()));
     return Result.first->second;
   }
 
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -868,16 +868,11 @@
       }
 
       if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(ND)) {
-        // FIXME: Invented mangling for decomposition declarations:
-        //   [X,Y,Z]
-        // where X,Y,Z are the names of the bindings.
-        llvm::SmallString<128> Name("[");
-        for (auto *BD : DD->bindings()) {
-          if (Name.size() > 1)
-            Name += ',';
-          Name += BD->getDeclName().getAsIdentifierInfo()->getName();
-        }
-        Name += ']';
+        // Decomposition declarations are considered anonymous, and get
+        // numbered with a $S prefix.
+        llvm::SmallString<64> Name("$S");
+        // Get a unique id for the anonymous struct.
+        Name += llvm::utostr(Context.getAnonymousStructId(DD) + 1);
         mangleSourceName(Name);
         break;
       }