diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 7dddeaac50788..266e651bac3a8 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -41629,7 +41629,7 @@ namespace ts {
             if (symbol && (symbol.flags & SymbolFlags.EnumMember)) {
                 // inline property\index accesses only for const enums
                 const member = symbol.valueDeclaration as EnumMember;
-                if (isEnumConst(member.parent)) {
+                if (isEnumConst(member.parent) || host.getProjectReferenceRedirect(getSourceFileOfNode(member).originalFileName)) {
                     return getEnumMemberValue(member);
                 }
             }
diff --git a/src/compiler/transformers/declarations.ts b/src/compiler/transformers/declarations.ts
index 6cea3b85055ee..175f08f8b4c9e 100644
--- a/src/compiler/transformers/declarations.ts
+++ b/src/compiler/transformers/declarations.ts
@@ -1577,6 +1577,10 @@ namespace ts {
                 mask ^= ModifierFlags.Ambient;
                 additions = ModifierFlags.None;
             }
+            // Transform non-ambient const enums -> ambient non-const enums if preserveConstEnums is true
+            if (!(node.flags & NodeFlags.Ambient) && isEnumDeclaration(node) && shouldPreserveConstEnums(options)) {
+                mask ^= ModifierFlags.Const;
+            }
             return maskModifierFlags(node, mask, additions);
         }