diff --git a/llvm/lib/Target/X86/X86CallingConv.td b/llvm/lib/Target/X86/X86CallingConv.td
--- a/llvm/lib/Target/X86/X86CallingConv.td
+++ b/llvm/lib/Target/X86/X86CallingConv.td
@@ -862,8 +862,8 @@
   // Doubles get 8-byte slots that are 4-byte aligned.
   CCIfType<[f64], CCAssignToStack<8, 4>>,
 
-  // Long doubles get slots whose size depends on the subtarget.
-  CCIfType<[f80], CCAssignToStack<0, 4>>,
+  // Long doubles get slots whose size and alignment depends on the subtarget.
+  CCIfType<[f80], CCAssignToStack<0, 0>>,
 
   // Boolean vectors of AVX-512 are passed in SIMD registers.
   // The call from AVX to AVX-512 function should work,
diff --git a/llvm/test/CodeGen/X86/2007-09-27-LDIntrinsics.ll b/llvm/test/CodeGen/X86/2007-09-27-LDIntrinsics.ll
--- a/llvm/test/CodeGen/X86/2007-09-27-LDIntrinsics.ll
+++ b/llvm/test/CodeGen/X86/2007-09-27-LDIntrinsics.ll
@@ -8,8 +8,9 @@
 	ret x86_fp80 %tmp2
         
 ; CHECK-LABEL: foo:
-; CHECK: fldt 4(%esp)
+; CHECK: fldt 16(%esp)
 ; CHECK-NEXT: fsqrt
+; CHECK-NEXT: addl $12, %esp
 ; CHECK-NEXT: ret
 }
 
@@ -20,10 +21,11 @@
 	%tmp2 = call x86_fp80 @llvm.powi.f80.i32( x86_fp80 %x, i32 3 )
 	ret x86_fp80 %tmp2
 ; CHECK-LABEL: bar:
-; CHECK: fldt 4(%esp)
+; CHECK: fldt 16(%esp)
 ; CHECK-NEXT: fld	%st(0)
 ; CHECK-NEXT: fmul	%st(1)
 ; CHECK-NEXT: fmulp
+; CHECK-NEXT: addl $12, %esp
 ; CHECK-NEXT: ret
 }
 
diff --git a/llvm/test/CodeGen/X86/inline-asm-fpstack.ll b/llvm/test/CodeGen/X86/inline-asm-fpstack.ll
--- a/llvm/test/CodeGen/X86/inline-asm-fpstack.ll
+++ b/llvm/test/CodeGen/X86/inline-asm-fpstack.ll
@@ -29,10 +29,12 @@
 define void @test3(x86_fp80 %X) nounwind {
 ; CHECK-LABEL: test3:
 ; CHECK:       ## %bb.0:
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    ## InlineAsm Start
 ; CHECK-NEXT:    frob
 ; CHECK-NEXT:    ## InlineAsm End
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
   call void asm sideeffect "frob ", "{st(0)},~{st},~{dirflag},~{fpsr},~{flags}"( x86_fp80 %X)
   ret void
@@ -246,12 +248,14 @@
 define void @fist1(x86_fp80 %x, i32* %p) nounwind ssp {
 ; CHECK-LABEL: fist1:
 ; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    ## InlineAsm Start
 ; CHECK-NEXT:    fistl (%eax)
 ; CHECK-NEXT:    ## InlineAsm End
 ; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
 entry:
   tail call void asm sideeffect "fistl $1", "{st},*m,~{memory},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, i32* %p) nounwind
@@ -269,11 +273,13 @@
 define x86_fp80 @fist2(x86_fp80 %x, i32* %p) nounwind ssp {
 ; CHECK-LABEL: fist2:
 ; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    ## InlineAsm Start
 ; CHECK-NEXT:    fistl (%eax)
 ; CHECK-NEXT:    ## InlineAsm End
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
 entry:
   %0 = tail call x86_fp80 asm "fistl $2", "=&{st},0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, i32* %p) nounwind
@@ -288,6 +294,7 @@
 define void @fucomp1(x86_fp80 %x, x86_fp80 %y) nounwind ssp {
 ; CHECK-LABEL: fucomp1:
 ; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fxch %st(1)
@@ -295,6 +302,7 @@
 ; CHECK-NEXT:    fucomp %st(1)
 ; CHECK-NEXT:    ## InlineAsm End
 ; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
 entry:
   tail call void asm sideeffect "fucomp $1", "{st},f,~{st},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind
@@ -314,6 +322,7 @@
 define void @fucomp2(x86_fp80 %x, x86_fp80 %y) nounwind ssp {
 ; CHECK-LABEL: fucomp2:
 ; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fxch %st(1)
@@ -321,6 +330,7 @@
 ; CHECK-NEXT:    fucomp %st(1)
 ; CHECK-NEXT:    ## InlineAsm End
 ; CHECK-NEXT:    fstp %st(0)
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
 entry:
   tail call void asm sideeffect "fucomp $1", "{st},{st(1)},~{st},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind
@@ -330,12 +340,14 @@
 define void @fucomp3(x86_fp80 %x, x86_fp80 %y) nounwind ssp {
 ; CHECK-LABEL: fucomp3:
 ; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fldt {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    fxch %st(1)
 ; CHECK-NEXT:    ## InlineAsm Start
 ; CHECK-NEXT:    fucompp %st(1)
 ; CHECK-NEXT:    ## InlineAsm End
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    retl
 entry:
   tail call void asm sideeffect "fucompp $1", "{st},{st(1)},~{st},~{st(1)},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind