Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -1108,6 +1108,7 @@
   bool IsWin32StructABI;
   bool IsSoftFloatABI;
   bool IsMCUABI;
+  bool IsLinuxABI;
   unsigned DefaultNumRegisterParameters;
 
   static bool isRegisterSize(unsigned Size) {
@@ -1173,6 +1174,7 @@
       IsWin32StructABI(Win32StructABI),
       IsSoftFloatABI(SoftFloatABI),
       IsMCUABI(CGT.getTarget().getTriple().isOSIAMCU()),
+      IsLinuxABI(CGT.getTarget().getTriple().isOSLinux()),
       DefaultNumRegisterParameters(NumRegisterParameters) {}
 
   bool shouldPassIndirectlyForSwift(ArrayRef<llvm::Type*> scalars,
@@ -1597,6 +1599,9 @@
   if (Align <= MinABIStackAlignInBytes)
     return 0; // Use default alignment.
 
+  if (IsLinuxABI && Ty->isFloatingType() && getContext().getTypeSize(Ty) == 128)
+    return 16;
+
   // On non-Darwin, the stack type alignment is always 4.
   if (!IsDarwinVectorABI) {
     // Set explicit alignment, since we may need to realign the top.
@@ -1890,6 +1895,9 @@
     return getIndirectResult(Ty, /*ByVal=*/false, State);
   }
 
+  if (IsLinuxABI && Ty->isFloatingType() && getContext().getTypeSize(Ty) == 128)
+    return getIndirectResult(Ty, /*ByVal=*/true, State);
+
   if (InReg)
     return ABIArgInfo::getDirectInReg();
   return ABIArgInfo::getDirect();
Index: clang/test/CodeGen/x86-long-double.cpp
===================================================================
--- clang/test/CodeGen/x86-long-double.cpp
+++ clang/test/CodeGen/x86-long-double.cpp
@@ -16,14 +16,14 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=x86_64-apple-darwin -mlong-double-64 | \
 // RUN:   FileCheck --check-prefixes=FP64,FP64-X64 %s
 
-// RUN: %clang_cc1 %s -emit-llvm -o - -triple=i686 -mlong-double-128 | \
-// RUN:   FileCheck --check-prefix=FP128 %s
+// RUN: %clang_cc1 %s -emit-llvm -o - -triple=i386-pc-linux-gnu -mlong-double-128 | \
+// RUN:   FileCheck --check-prefixes=FP128,FP128-X32-LINUX %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=i686-apple-darwin -mlong-double-128 | \
-// RUN:   FileCheck --check-prefix=FP128 %s
+// RUN:   FileCheck --check-prefixes=FP128,FP128-X32-DARWIN %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=x86_64 -mlong-double-128 | \
-// RUN:   FileCheck --check-prefix=FP128 %s
+// RUN:   FileCheck --check-prefixes=FP128,FP128-X64 %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=x86_64-apple-darwin -mlong-double-128 | \
-// RUN:   FileCheck --check-prefix=FP128 %s
+// RUN:   FileCheck --check-prefixes=FP128,FP128-X64 %s
 
 // Check -malign-double increases the alignment from 4 to 8 on x86-32.
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=i686 -mlong-double-64 \
@@ -53,4 +53,6 @@
 
 // FP64: double @_Z3fooe(double %d)
 // FP80: x86_fp80 @_Z3fooe(x86_fp80 %d)
-// FP128: fp128 @_Z3foog(fp128 %d)
+// FP128-X32-LINUX: fp128 @_Z3foog(fp128* byval(fp128) align 16 %0)
+// FP128-X32-DARWIN: fp128 @_Z3foog(fp128 %d)
+// FP128-X64: fp128 @_Z3foog(fp128 %d)
Index: clang/test/CodeGen/x86_32-fp128-call-conv-linux.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/x86_32-fp128-call-conv-linux.c
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -mlong-double-128 -w -fblocks -ffreestanding -triple i386-pc-linux-gnu -emit-llvm -o %t %s || FileCheck < %t %s
+
+
+// CHECK-LABEL: define void @testfp128
+// CHECK-NEXT:  %a.addr = alloca fp128, align 16
+// CHECK-NEXT:  %a = load fp128, fp128* %0, align 16
+// CHECK-NEXT:  store fp128 %a, fp128* %a.addr, align 16
+void testfp128(__float128 a) {
+  return;
+}
+
+// CHECK-LABEL: define void @testlongdouble
+// CHECK-NEXT:  %a.addr = alloca fp128, align 16
+// CHECK-NEXT:  %a = load fp128, fp128* %0, align 16
+// CHECK-NEXT:  store fp128 %a, fp128* %a.addr, align 16
+void testlongdouble(long double a) {
+  return;
+}
+
+// CHECK-LABEL: define void @testPassArguments
+// CHECK:       call void @testfp128(fp128* byval(fp128) align 16 %{{.*}})
+// CHECK:       call void @testlongdouble(fp128* byval(fp128) align 16 %{{.*}})
+void testPassArguments() {
+  __float128 a=1.0;
+  testfp128(a);
+  testlongdouble(a);
+  return;
+}