diff --git a/llvm/test/CodeGen/X86/musttail-indirect.ll b/llvm/test/CodeGen/X86/musttail-indirect.ll
index 285ad9dcf4c91..5d2e0694e3444 100644
--- a/llvm/test/CodeGen/X86/musttail-indirect.ll
+++ b/llvm/test/CodeGen/X86/musttail-indirect.ll
@@ -22,8 +22,6 @@
 ; Each member pointer creates a thunk.  The ones with inalloca are required to
 ; tail calls by the ABI, even at O0.
 
-; TODO: add tests for preallocated/musttail once supported
-
 %struct.B = type { i32 (...)** }
 %struct.A = type { i32 }
 
@@ -54,6 +52,21 @@ entry:
   ret i32 %3
 }
 
+; Preallocated thunks shouldn't require any stores to the stack.
+; CHECK-LABEL: g_thunk_preallocated:
+; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
+; CHECK: jmpl
+; CHECK-NOT: ret
+define x86_thiscallcc i32 @g_thunk_preallocated(%struct.B* %this, <{ %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A, i32, %struct.A }>)) {
+entry:
+  %1 = bitcast %struct.B* %this to i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)***
+  %vtable = load i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)**, i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*** %1
+  %vfn = getelementptr inbounds i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*, i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)** %vtable, i32 1
+  %2 = load i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*, i32 (%struct.B*, <{ %struct.A, i32, %struct.A }>*)** %vfn
+  %3 = musttail call x86_thiscallcc i32 %2(%struct.B* %this, <{ %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A, i32, %struct.A }>) %0)
+  ret i32 %3
+}
+
 ; CHECK-LABEL: h_thunk:
 ; CHECK: jmpl
 ; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
@@ -68,6 +81,20 @@ entry:
   ret void
 }
 
+; CHECK-LABEL: h_thunk_preallocated:
+; CHECK: jmpl
+; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
+; CHECK-NOT: ret
+define x86_thiscallcc void @h_thunk_preallocated(%struct.B* %this, <{ %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A, i32, %struct.A }>)) {
+entry:
+  %1 = bitcast %struct.B* %this to void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)***
+  %vtable = load void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)**, void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*** %1
+  %vfn = getelementptr inbounds void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*, void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)** %vtable, i32 2
+  %2 = load void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)*, void (%struct.B*, <{ %struct.A, i32, %struct.A }>*)** %vfn
+  musttail call x86_thiscallcc void %2(%struct.B* %this, <{ %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A, i32, %struct.A }>) %0)
+  ret void
+}
+
 ; CHECK-LABEL: i_thunk:
 ; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
 ; CHECK: jmpl
@@ -82,6 +109,20 @@ entry:
   ret %struct.A* %3
 }
 
+; CHECK-LABEL: i_thunk_preallocated:
+; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
+; CHECK: jmpl
+; CHECK-NOT: ret
+define x86_thiscallcc %struct.A* @i_thunk_preallocated(%struct.B* %this, <{ %struct.A*, %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A*, %struct.A, i32, %struct.A }>)) {
+entry:
+  %1 = bitcast %struct.B* %this to %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)***
+  %vtable = load %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)**, %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)*** %1
+  %vfn = getelementptr inbounds %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)*, %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)** %vtable, i32 3
+  %2 = load %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)*, %struct.A* (%struct.B*, <{ %struct.A*, %struct.A, i32, %struct.A }>*)** %vfn
+  %3 = musttail call x86_thiscallcc %struct.A* %2(%struct.B* %this, <{ %struct.A*, %struct.A, i32, %struct.A }>* preallocated(<{ %struct.A*, %struct.A, i32, %struct.A }>) %0)
+  ret %struct.A* %3
+}
+
 ; CHECK-LABEL: j_thunk:
 ; CHECK: jmpl
 ; CHECK-NOT: ret
@@ -111,6 +152,22 @@ entry:
   ret i32 %3
 }
 
+; CHECK-LABEL: _stdcall_thunk_preallocated@8:
+; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
+; CHECK: jmpl
+; CHECK-NOT: ret
+define x86_stdcallcc i32 @stdcall_thunk_preallocated(<{ %struct.B*, %struct.A }>* preallocated(<{ %struct.B*, %struct.A }>)) {
+entry:
+  %this_ptr = getelementptr inbounds <{ %struct.B*, %struct.A }>, <{ %struct.B*, %struct.A }>* %0, i32 0, i32 0
+  %this = load %struct.B*, %struct.B** %this_ptr
+  %1 = bitcast %struct.B* %this to i32 (<{ %struct.B*, %struct.A }>*)***
+  %vtable = load i32 (<{ %struct.B*, %struct.A }>*)**, i32 (<{ %struct.B*, %struct.A }>*)*** %1
+  %vfn = getelementptr inbounds i32 (<{ %struct.B*, %struct.A }>*)*, i32 (<{ %struct.B*, %struct.A }>*)** %vtable, i32 1
+  %2 = load i32 (<{ %struct.B*, %struct.A }>*)*, i32 (<{ %struct.B*, %struct.A }>*)** %vfn
+  %3 = musttail call x86_stdcallcc i32 %2(<{ %struct.B*, %struct.A }>* preallocated(<{ %struct.B*, %struct.A }>) %0)
+  ret i32 %3
+}
+
 ; CHECK-LABEL: @fastcall_thunk@8:
 ; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
 ; CHECK: jmpl
@@ -124,3 +181,17 @@ entry:
   %3 = musttail call x86_fastcallcc i32 %2(%struct.B* inreg %this, <{ %struct.A }>* inalloca %0)
   ret i32 %3
 }
+
+; CHECK-LABEL: @fastcall_thunk_preallocated@8:
+; CHECK-NOT: mov %{{.*}}, {{.*(.*esp.*)}}
+; CHECK: jmpl
+; CHECK-NOT: ret
+define x86_fastcallcc i32 @fastcall_thunk_preallocated(%struct.B* inreg %this, <{ %struct.A }>* preallocated(<{ %struct.A }>)) {
+entry:
+  %1 = bitcast %struct.B* %this to i32 (%struct.B*, <{ %struct.A }>*)***
+  %vtable = load i32 (%struct.B*, <{ %struct.A }>*)**, i32 (%struct.B*, <{ %struct.A }>*)*** %1
+  %vfn = getelementptr inbounds i32 (%struct.B*, <{ %struct.A }>*)*, i32 (%struct.B*, <{ %struct.A }>*)** %vtable, i32 1
+  %2 = load i32 (%struct.B*, <{ %struct.A }>*)*, i32 (%struct.B*, <{ %struct.A }>*)** %vfn
+  %3 = musttail call x86_fastcallcc i32 %2(%struct.B* inreg %this, <{ %struct.A }>* preallocated(<{ %struct.A }>) %0)
+  ret i32 %3
+}
diff --git a/llvm/test/CodeGen/X86/musttail-thiscall.ll b/llvm/test/CodeGen/X86/musttail-thiscall.ll
index 5cc8faa48e754..682f85e1eb852 100644
--- a/llvm/test/CodeGen/X86/musttail-thiscall.ll
+++ b/llvm/test/CodeGen/X86/musttail-thiscall.ll
@@ -1,8 +1,6 @@
 ; RUN: llc -verify-machineinstrs -mtriple=i686-- < %s | FileCheck %s
 ; RUN: llc -verify-machineinstrs -mtriple=i686-- -O0 < %s | FileCheck %s
 
-; TODO: add tests for preallocated/musttail once supported
-
 ; CHECK-LABEL: t1:
 ; CHECK: jmp {{_?}}t1_callee
 define x86_thiscallcc void @t1(i8* %this) {
@@ -31,3 +29,14 @@ define x86_thiscallcc i8* @t3(i8* %this, <{ i8*, i32 }>* inalloca %args) {
   ret i8* %rv
 }
 declare x86_thiscallcc i8* @t3_callee(i8* %this, <{ i8*, i32 }>* inalloca %args);
+
+; CHECK-LABEL: t4:
+; CHECK: jmp {{_?}}t4_callee
+define x86_thiscallcc i8* @t4(i8* %this, <{ i8*, i32 }>* preallocated(<{ i8*, i32 }>) %args) {
+  %adj = getelementptr i8, i8* %this, i32 4
+  %a_ptr = getelementptr <{ i8*, i32 }>, <{ i8*, i32 }>* %args, i32 0, i32 1
+  store i32 0, i32* %a_ptr
+  %rv = musttail call x86_thiscallcc i8* @t4_callee(i8* %adj, <{ i8*, i32 }>* preallocated(<{ i8*, i32 }>) %args)
+  ret i8* %rv
+}
+declare x86_thiscallcc i8* @t4_callee(i8* %this, <{ i8*, i32 }>* preallocated(<{ i8*, i32 }>) %args);