Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -15192,10 +15192,10 @@
   MemOps.push_back(Store);
 
   // Store ptr to reg_save_area.
-  FIN = DAG.getNode(ISD::ADD, DL, PtrVT, FIN, DAG.getIntPtrConstant(8, DL));
+  FIN = DAG.getNode(ISD::ADD, DL, PtrVT, FIN, DAG.getIntPtrConstant(Subtarget->isTarget64BitLP64() ? 8 : 4, DL));
   SDValue RSFIN = DAG.getFrameIndex(FuncInfo->getRegSaveFrameIndex(), PtrVT);
   Store = DAG.getStore(Op.getOperand(0), DL, RSFIN, FIN,
-                       MachinePointerInfo(SV, 16), false, false, 0);
+                       MachinePointerInfo(SV, Subtarget->isTarget64BitLP64() ? 16 : 12), false, false, 0);
   MemOps.push_back(Store);
   return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, MemOps);
 }
Index: test/CodeGen/X86/musttail-varargs.ll
===================================================================
--- test/CodeGen/X86/musttail-varargs.ll
+++ test/CodeGen/X86/musttail-varargs.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -enable-tail-merge=0 -mtriple=x86_64-linux | FileCheck %s --check-prefix=LINUX
+; RUN: llc < %s -enable-tail-merge=0 -mtriple=x86_64-linux-gnux32 | FileCheck %s --check-prefix=LINUX-X32
 ; RUN: llc < %s -enable-tail-merge=0 -mtriple=x86_64-windows | FileCheck %s --check-prefix=WINDOWS
 ; RUN: llc < %s -enable-tail-merge=0 -mtriple=i686-windows | FileCheck %s --check-prefix=X86
 
@@ -57,6 +58,40 @@
 ; LINUX-DAG: movb {{.*}}, %al
 ; LINUX: jmpq *{{.*}}  # TAILCALL
 
+; LINUX-X32-LABEL: f_thunk:
+; LINUX-X32-DAG: movl %edi, {{.*}}
+; LINUX-X32-DAG: movq %rsi, {{.*}}
+; LINUX-X32-DAG: movq %rdx, {{.*}}
+; LINUX-X32-DAG: movq %rcx, {{.*}}
+; LINUX-X32-DAG: movq %r8, {{.*}}
+; LINUX-X32-DAG: movq %r9, {{.*}}
+; LINUX-X32-DAG: movb %al, {{.*}}
+; LINUX-X32-DAG: movaps %xmm0, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm1, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm2, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm3, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm4, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm5, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm6, {{[0-9]*}}(%esp)
+; LINUX-X32-DAG: movaps %xmm7, {{[0-9]*}}(%esp)
+; LINUX-X32: callq get_f
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm0
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm1
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm2
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm3
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm4
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm5
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm6
+; LINUX-X32-DAG: movaps {{[0-9]*}}(%esp), %xmm7
+; LINUX-X32-DAG: movl {{.*}}, %edi
+; LINUX-X32-DAG: movq {{.*}}, %rsi
+; LINUX-X32-DAG: movq {{.*}}, %rdx
+; LINUX-X32-DAG: movq {{.*}}, %rcx
+; LINUX-X32-DAG: movq {{.*}}, %r8
+; LINUX-X32-DAG: movq {{.*}}, %r9
+; LINUX-X32-DAG: movb {{.*}}, %al
+; LINUX-X32: jmpq *{{.*}}  # TAILCALL
+
 ; WINDOWS-LABEL: f_thunk:
 ; WINDOWS-NOT: mov{{.}}ps
 ; WINDOWS-DAG: movq %rdx, {{.*}}
@@ -92,6 +127,10 @@
 ; LINUX-NOT: movq
 ; LINUX: jmpq *%rdi  # TAILCALL
 
+; LINUX-X32-LABEL: g_thunk:
+; LINUX-X32-DAG: movl %edi, %[[REG:e[abcd]x|ebp|esi|edi|r8|r9|r1[0-5]]]
+; LINUX-X32-DAG: jmpq *%[[REG]]  # TAILCALL
+
 ; WINDOWS-LABEL: g_thunk:
 ; WINDOWS-NOT: movq
 ; WINDOWS: jmpq *%rcx # TAILCALL
@@ -130,6 +169,10 @@
 ; LINUX: jne
 ; LINUX: jmpq *{{.*}} # TAILCALL
 ; LINUX: jmpq *{{.*}} # TAILCALL
+; LINUX-X32-LABEL: h_thunk:
+; LINUX-X32: jne
+; LINUX-X32: jmpq *{{.*}} # TAILCALL
+; LINUX-X32: jmpq *{{.*}} # TAILCALL
 ; WINDOWS-LABEL: h_thunk:
 ; WINDOWS: jne
 ; WINDOWS: jmpq *{{.*}} # TAILCALL
Index: test/CodeGen/X86/nosse-varargs.ll
===================================================================
--- test/CodeGen/X86/nosse-varargs.ll
+++ test/CodeGen/X86/nosse-varargs.ll
@@ -1,5 +1,7 @@
 ; RUN: llc < %s -march=x86-64 -mattr=-sse | FileCheck %s -check-prefix=NOSSE
+; RUN: llc < %s -mtriple=x86_64-gnux32 -mattr=-sse | FileCheck %s -check-prefix=NOSSE
 ; RUN: llc < %s -march=x86-64 | FileCheck %s -check-prefix=YESSSE
+; RUN: llc < %s -mtriple=x86_64-gnux32 | FileCheck %s -check-prefix=YESSSE
 ; PR3403
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
 target triple = "x86_64-unknown-linux-gnu"
Index: test/CodeGen/X86/soft-fp.ll
===================================================================
--- test/CodeGen/X86/soft-fp.ll
+++ test/CodeGen/X86/soft-fp.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -march=x86    -mattr=+sse2,+soft-float | FileCheck %s
 ; RUN: llc < %s -march=x86-64 -mattr=+sse2,+soft-float | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-gnux32 -mattr=+sse2,+soft-float | FileCheck %s
 
 ; CHECK-NOT: xmm{[0-9]+}
 
Index: test/CodeGen/X86/stdarg.ll
===================================================================
--- test/CodeGen/X86/stdarg.ll
+++ test/CodeGen/X86/stdarg.ll
@@ -1,5 +1,5 @@
-; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s
-; CHECK: testb %al, %al
+; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s -check-prefix=X8664 -check-prefix=CHECK
+; RUN: llc < %s -mtriple=x86_64-linux-gnux32 | FileCheck %s -check-prefix=X32 -check-prefix=CHECK
 
 %struct.__va_list_tag = type { i32, i32, i8*, i8* }
 
@@ -8,6 +8,19 @@
   %ap = alloca [1 x %struct.__va_list_tag], align 8; <[1 x %struct.__va_list_tag]*> [#uses=2]
   %ap12 = bitcast [1 x %struct.__va_list_tag]* %ap to i8*; <i8*> [#uses=2]
   call void @llvm.va_start(i8* %ap12)
+; CHECK: testb %al, %al
+
+; These test for specific offsets, which is very fragile. Still, the test needs to ensure that
+; va_list is correctly handled by both x86-64 and x32.
+;
+; X8664-DAG: movq {{.*}}, 192(%rsp)
+; X8664-DAG: movq {{.*}}, 184(%rsp)
+; X8664-DAG: movl {{.*}}, 180(%rsp)
+; X8664-DAG: movl {{.*}}, 176(%rsp)
+; X32-DAG: movl {{.*}}, 196(%esp)
+; X32-DAG: movl {{.*}}, 192(%esp)
+; X32-DAG: movl {{.*}}, 188(%esp)
+; X32-DAG: movl {{.*}}, 184(%esp)
   %ap3 = getelementptr inbounds [1 x %struct.__va_list_tag], [1 x %struct.__va_list_tag]* %ap, i64 0, i64 0; <%struct.__va_list_tag*> [#uses=1]
   call void @bar(%struct.__va_list_tag* %ap3) nounwind
   call void @llvm.va_end(i8* %ap12)