Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -2835,31 +2835,6 @@
       return;
     } else if (isa<VariableArrayType>(VD->getType()))
       Expr.push_back(llvm::dwarf::DW_OP_deref);
-  } else if (const RecordType *RT = dyn_cast<RecordType>(VD->getType())) {
-    // If VD is an anonymous union then Storage represents value for
-    // all union fields.
-    const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
-    if (RD->isUnion() && RD->isAnonymousStructOrUnion()) {
-      for (const auto *Field : RD->fields()) {
-        llvm::MDType *FieldTy = getOrCreateType(Field->getType(), Unit);
-        StringRef FieldName = Field->getName();
-
-        // Ignore unnamed fields. Do not ignore unnamed records.
-        if (FieldName.empty() && !isa<RecordType>(Field->getType()))
-          continue;
-
-        // Use VarDecl's Tag, Scope and Line number.
-        auto *D = DBuilder.createLocalVariable(
-            Tag, Scope, FieldName, Unit, Line, FieldTy,
-            CGM.getLangOpts().Optimize, Flags, ArgNo);
-
-        // Insert an llvm.dbg.declare into the current block.
-        DBuilder.insertDeclare(Storage, D, DBuilder.createExpression(Expr),
-                               llvm::DebugLoc::get(Line, Column, Scope),
-                               Builder.GetInsertBlock());
-      }
-      return;
-    }
   }
 
   // Create the descriptor for the variable.
Index: test/CodeGenCXX/debug-info-anon-union-vars.cpp
===================================================================
--- test/CodeGenCXX/debug-info-anon-union-vars.cpp
+++ test/CodeGenCXX/debug-info-anon-union-vars.cpp
@@ -21,8 +21,26 @@
   return (c == 1);
 }
 
+// This is not necessary (and actually harmful because it breaks IR assumptions)
+// for local variables.
+void foo() {
+  union {
+    int i;
+    char c;
+  };
+  i = 8;
+}
+
 // CHECK: [[FILE:.*]] = !MDFile(filename: "{{.*}}debug-info-anon-union-vars.cpp",
 // CHECK: !MDGlobalVariable(name: "c",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
 // CHECK: !MDGlobalVariable(name: "d",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
 // CHECK: !MDGlobalVariable(name: "a",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
 // CHECK: !MDGlobalVariable(name: "b",{{.*}} file: [[FILE]], line: 6,{{.*}} isLocal: true, isDefinition: true
+// CHECK: !MDLocalVariable(
+// CHECK-NOT: name:
+// CHECK: type: ![[UNION:[0-9]+]]
+// CHECK: ![[UNION]] = !MDCompositeType(tag: DW_TAG_union_type,
+// CHECK-NOT: name:
+// CHECK: elements
+// CHECK: !MDDerivedType(tag: DW_TAG_member, name: "i", scope: ![[UNION]],
+// CHECK: !MDDerivedType(tag: DW_TAG_member, name: "c", scope: ![[UNION]],