diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
--- a/clang/include/clang/Basic/TargetInfo.h
+++ b/clang/include/clang/Basic/TargetInfo.h
@@ -15,6 +15,7 @@
 #define LLVM_CLANG_BASIC_TARGETINFO_H
 
 #include "clang/Basic/AddressSpaces.h"
+#include "clang/Basic/BitmaskEnum.h"
 #include "clang/Basic/CodeGenOptions.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
@@ -52,14 +53,14 @@
 namespace Builtin { struct Info; }
 
 enum class FloatModeKind {
-  NoFloat = 255,
-  Half = 0,
-  Float,
-  Double,
-  LongDouble,
-  Float128,
-  Ibm128,
-  Last = Ibm128
+  NoFloat = 0,
+  Half = 1 << 0,
+  Float = 1 << 1,
+  Double = 1 << 2,
+  LongDouble = 1 << 3,
+  Float128 = 1 << 4,
+  Ibm128 = 1 << 5,
+  LLVM_MARK_AS_BITMASK_ENUM(Ibm128)
 };
 
 /// Fields controlling how types are laid out in memory; these may need to
@@ -221,7 +222,9 @@
   mutable VersionTuple PlatformMinVersion;
 
   unsigned HasAlignMac68kSupport : 1;
-  unsigned RealTypeUsesObjCFPRetMask : (int)FloatModeKind::Last + 1;
+  unsigned RealTypeUsesObjCFPRetMask
+      : llvm::BitmaskEnumDetail::bitWidth(
+            (int)FloatModeKind::LLVM_BITMASK_LARGEST_ENUMERATOR);
   unsigned ComplexLongDoubleUsesFP2Ret : 1;
 
   unsigned HasBuiltinMSVaList : 1;
@@ -890,9 +893,7 @@
   /// Check whether the given real type should use the "fpret" flavor of
   /// Objective-C message passing on this target.
   bool useObjCFPRetForRealType(FloatModeKind T) const {
-    assert(T <= FloatModeKind::Last &&
-           "T value is larger than RealTypeUsesObjCFPRetMask can handle");
-    return RealTypeUsesObjCFPRetMask & (1 << (int)T);
+    return RealTypeUsesObjCFPRetMask & llvm::BitmaskEnumDetail::Underlying(T);
   }
 
   /// Check whether _Complex long double should use the "fp2ret" flavor
diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
--- a/clang/lib/Basic/Targets/X86.h
+++ b/clang/lib/Basic/Targets/X86.h
@@ -14,6 +14,7 @@
 #define LLVM_CLANG_LIB_BASIC_TARGETS_X86_H
 
 #include "OSTargets.h"
+#include "clang/Basic/BitmaskEnum.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/TargetOptions.h"
 #include "llvm/ADT/Triple.h"
@@ -419,8 +420,8 @@
 
     // Use fpret for all types.
     RealTypeUsesObjCFPRetMask =
-        ((1 << (int)FloatModeKind::Float) | (1 << (int)FloatModeKind::Double) |
-         (1 << (int)FloatModeKind::LongDouble));
+        (int)(FloatModeKind::Float | FloatModeKind::Double |
+              FloatModeKind::LongDouble);
 
     // x86-32 has atomics up to 8 bytes
     MaxAtomicPromoteWidth = 64;
@@ -699,7 +700,7 @@
                                         "64-i64:64-f80:128-n8:16:32:64-S128");
 
     // Use fpret only for long double.
-    RealTypeUsesObjCFPRetMask = (1 << (int)FloatModeKind::LongDouble);
+    RealTypeUsesObjCFPRetMask = (int)FloatModeKind::LongDouble;
 
     // Use fp2ret for _Complex long double.
     ComplexLongDoubleUsesFP2Ret = true;