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
@@ -204,6 +204,7 @@
   bool HasBFloat16;
   bool HasIbm128;
   bool HasLongDouble;
+  bool Has80BitLongDouble;
   bool HasFPReturn;
   bool HasStrictFP;
 
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -38,6 +38,7 @@
   HasFloat16 = false;
   HasBFloat16 = false;
   HasLongDouble = true;
+  Has80BitLongDouble = false;
   HasFPReturn = true;
   HasStrictFP = false;
   PointerWidth = PointerAlign = 32;
@@ -449,6 +450,9 @@
     }
   }
 
+  if (LongDoubleFormat == &llvm::APFloat::x87DoubleExtended())
+    HasLongDouble = Has80BitLongDouble;
+
   if (Opts.NewAlignOverride)
     NewAlign = Opts.NewAlignOverride * getCharWidth();
 
diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
--- a/clang/lib/Basic/Targets/X86.cpp
+++ b/clang/lib/Basic/Targets/X86.cpp
@@ -384,8 +384,8 @@
 
   // FIXME: We should allow long double type on 32-bits to match with GCC.
   // This requires backend to be able to lower f80 without x87 first.
-  if (!HasX87 && LongDoubleFormat == &llvm::APFloat::x87DoubleExtended())
-    HasLongDouble = false;
+  if (HasX87)
+    Has80BitLongDouble = true;
 
   if (SSELevel < SSE1 && getTriple().getArch() == llvm::Triple::x86_64)
     HasFPReturn = false;
diff --git a/clang/test/Sema/x86-no-x87.cpp b/clang/test/Sema/x86-no-x87.cpp
--- a/clang/test/Sema/x86-no-x87.cpp
+++ b/clang/test/Sema/x86-no-x87.cpp
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple i686-linux-gnu -target-feature -x87
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple i686-linux-gnu -DNOERROR
+// RUN: %clang_cc1 -fsyntax-only -verify %s -triple i686-linux-gnu -mlong-double-64 -DNOERROR
 
 #ifdef NOERROR
 // expected-no-diagnostics
diff --git a/clang/test/Sema/x86_64-no-x87.cpp b/clang/test/Sema/x86_64-no-x87.cpp
--- a/clang/test/Sema/x86_64-no-x87.cpp
+++ b/clang/test/Sema/x86_64-no-x87.cpp
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-linux-gnu -target-feature -x87 -target-feature -sse -DERROR_LONGDOUBLE -DERROR_NOSSE
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-linux-gnu -target-feature -x87 -DERROR_LONGDOUBLE
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-linux-gnu -DNOERROR
+// RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-linux-gnu -mlong-double-64 -DNOERROR
 
 #ifdef NOERROR
 // expected-no-diagnostics