diff --git a/clang/include/clang/AST/PrettyPrinter.h b/clang/include/clang/AST/PrettyPrinter.h
index fd995a653d167..48105b3b9d4cd 100644
--- a/clang/include/clang/AST/PrettyPrinter.h
+++ b/clang/include/clang/AST/PrettyPrinter.h
@@ -15,6 +15,7 @@
 
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
+#include "llvm/ADT/STLForwardCompat.h"
 
 namespace clang {
 
@@ -55,14 +56,15 @@ class PrintingCallbacks {
 /// This type is intended to be small and suitable for passing by value.
 /// It is very frequently copied.
 struct PrintingPolicy {
-  enum SuppressInlineNamespaceMode : uint8_t { None, Redundant, All };
+  enum class SuppressInlineNamespaceMode : uint8_t { None, Redundant, All };
 
   /// Create a default printing policy for the specified language.
   PrintingPolicy(const LangOptions &LO)
       : Indentation(2), SuppressSpecifiers(false),
         SuppressTagKeyword(LO.CPlusPlus), IncludeTagDefinition(false),
         SuppressScope(false), SuppressUnwrittenScope(false),
-        SuppressInlineNamespace(SuppressInlineNamespaceMode::Redundant),
+        SuppressInlineNamespace(
+            llvm::to_underlying(SuppressInlineNamespaceMode::Redundant)),
         SuppressInitializers(false), ConstantArraySizeAsWritten(false),
         AnonymousTagLocations(true), SuppressStrongLifetime(false),
         SuppressLifetimeQualifiers(false),
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 591457b1d66b4..4444b10db8cc0 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1753,9 +1753,11 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
     // Suppress inline namespace if it doesn't make the result ambiguous.
     if (Ctx->isInlineNamespace() && NameInScope) {
       if (P.SuppressInlineNamespace ==
-              PrintingPolicy::SuppressInlineNamespaceMode::All ||
+              llvm::to_underlying(
+                  PrintingPolicy::SuppressInlineNamespaceMode::All) ||
           (P.SuppressInlineNamespace ==
-               PrintingPolicy::SuppressInlineNamespaceMode::Redundant &&
+               llvm::to_underlying(
+                   PrintingPolicy::SuppressInlineNamespaceMode::Redundant) &&
            cast<NamespaceDecl>(Ctx)->isRedundantInlineQualifierFor(
                NameInScope))) {
         continue;
diff --git a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
index fbb8b49676045..a556ffca96903 100644
--- a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
@@ -654,9 +654,9 @@ bool HasNameMatcher::matchesNodeFullSlow(const NamedDecl &Node) const {
 
     PrintingPolicy Policy = Node.getASTContext().getPrintingPolicy();
     Policy.SuppressUnwrittenScope = SkipUnwritten;
-    Policy.SuppressInlineNamespace =
+    Policy.SuppressInlineNamespace = llvm::to_underlying(
         SkipUnwritten ? PrintingPolicy::SuppressInlineNamespaceMode::All
-                      : PrintingPolicy::SuppressInlineNamespaceMode::None;
+                      : PrintingPolicy::SuppressInlineNamespaceMode::None);
     Node.printQualifiedName(OS, Policy);
 
     const StringRef FullName = OS.str();
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index efc2c6c0ba500..24b106b4bcee7 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -97,7 +97,8 @@ std::string CIRGenTypes::getRecordTypeName(const clang::RecordDecl *recordDecl,
   llvm::raw_svector_ostream outStream(typeName);
 
   PrintingPolicy policy = recordDecl->getASTContext().getPrintingPolicy();
-  policy.SuppressInlineNamespace = false;
+  policy.SuppressInlineNamespace =
+      llvm::to_underlying(PrintingPolicy::SuppressInlineNamespaceMode::None);
   policy.AlwaysIncludeTypeForTemplateArgument = true;
   policy.PrintAsCanonical = true;
   policy.SuppressTagKeyword = true;
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index c50f372c1f331..5a83c151901f9 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -417,7 +417,7 @@ PrintingPolicy CGDebugInfo::getPrintingPolicy() const {
   }
 
   PP.SuppressInlineNamespace =
-      PrintingPolicy::SuppressInlineNamespaceMode::None;
+      llvm::to_underlying(PrintingPolicy::SuppressInlineNamespaceMode::None);
   PP.PrintAsCanonical = true;
   PP.UsePreferredNames = false;
   PP.AlwaysIncludeTypeForTemplateArgument = true;
diff --git a/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index ea31195b7f92e..be862cf07f177 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -62,7 +62,7 @@ void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
   // FullyQualifiedNames.
   PrintingPolicy Policy = RD->getASTContext().getPrintingPolicy();
   Policy.SuppressInlineNamespace =
-      PrintingPolicy::SuppressInlineNamespaceMode::None;
+      llvm::to_underlying(PrintingPolicy::SuppressInlineNamespaceMode::None);
 
   // Name the codegen type after the typedef name
   // if there is no tag type name available
diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index aa8d309fbc730..2cb4a46130c84 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -2149,7 +2149,8 @@ PrintingPolicy TypeSystemClang::GetTypePrintingPolicy() {
   printing_policy.SuppressTagKeyword = true;
   // Inline namespaces are important for some type formatters (e.g., libc++
   // and libstdc++ are differentiated by their inline namespaces).
-  printing_policy.SuppressInlineNamespace = false;
+  printing_policy.SuppressInlineNamespace =
+      llvm::to_underlying(PrintingPolicy::SuppressInlineNamespaceMode::None);
   printing_policy.SuppressUnwrittenScope = false;
   // Default arguments are also always important for type formatters. Otherwise
   // we would need to always specify two type names for the setups where we do
@@ -3870,7 +3871,9 @@ TypeSystemClang::GetDisplayTypeName(lldb::opaque_compiler_type_t type) {
   printing_policy.SuppressTagKeyword = true;
   printing_policy.SuppressScope = false;
   printing_policy.SuppressUnwrittenScope = true;
-  printing_policy.SuppressInlineNamespace = true;
+  // FIXME: should we suppress "All" inline namespaces?
+  printing_policy.SuppressInlineNamespace = llvm::to_underlying(
+      PrintingPolicy::SuppressInlineNamespaceMode::Redundant);
   return ConstString(qual_type.getAsString(printing_policy));
 }