diff --git a/cranelift/filetests/filetests/isa/x64/call-conv.clif b/cranelift/filetests/filetests/isa/x64/call-conv.clif
new file mode 100644
index 000000000000..66af3e9fca87
--- /dev/null
+++ b/cranelift/filetests/filetests/isa/x64/call-conv.clif
@@ -0,0 +1,207 @@
+test compile
+target x86_64 machinst
+
+;; system_v has first param in %rdi, fascall in %rcx
+function %one_arg(i32) system_v {
+    sig0 = (i32) windows_fastcall
+block0(v0: i32):
+    ; check:  movq    %rdi, %rcx
+    ; nextln: call    *%rdi
+    call_indirect sig0, v0(v0)
+    return
+}
+
+;; system_v has params in %rdi, %xmm0, fascall in %rcx, %xmm1
+function %two_args(i32, f32) system_v {
+    sig0 = (i32, f32) windows_fastcall
+    sig1 = (i32, f32) system_v
+block0(v0: i32, v1: f32):
+    ; check:  movq    %rdi, %rsi
+    ; check:  movaps  %xmm0, %xmm6
+    ; check:  movq    %rsi, %rcx
+    ; nextln: movaps  %xmm6, %xmm1
+    ; nextln: call    *%rsi
+    call_indirect sig0, v0(v0, v1)
+
+    ; check:  movq    %rsi, %rdi
+    ; nextln: movaps  %xmm6, %xmm0
+    ; nextln: call    *%rsi
+    call_indirect sig1, v0(v0, v1)
+    return
+}
+
+;; fastcall preserves xmm6+, rbx, rbp, rdi, rsi, r12-r15
+;; system_v preserves no xmm registers, rbx, rbp, r12-r15
+function %fastcall_to_systemv(i32) windows_fastcall {
+    sig0 = () system_v
+block0(v0: i32):
+    ; check:  pushq   %rbp
+    ; nextln: movq    %rsp, %rbp
+    ; nextln: subq    $$176, %rsp
+    ; nextln: movdqu  %xmm6, 0(%rsp)
+    ; nextln: movdqu  %xmm7, 16(%rsp)
+    ; nextln: movdqu  %xmm8, 32(%rsp)
+    ; nextln: movdqu  %xmm9, 48(%rsp)
+    ; nextln: movdqu  %xmm10, 64(%rsp)
+    ; nextln: movdqu  %xmm11, 80(%rsp)
+    ; nextln: movdqu  %xmm12, 96(%rsp)
+    ; nextln: movdqu  %xmm13, 112(%rsp)
+    ; nextln: movdqu  %xmm14, 128(%rsp)
+    ; nextln: movdqu  %xmm15, 144(%rsp)
+    ; nextln: movq    %rsi, 160(%rsp)
+    ; nextln: movq    %rdi, 168(%rsp)
+    ; nextln: call    *%rcx
+    ; nextln: movdqu  0(%rsp), %xmm6
+    ; nextln: movdqu  16(%rsp), %xmm7
+    ; nextln: movdqu  32(%rsp), %xmm8
+    ; nextln: movdqu  48(%rsp), %xmm9
+    ; nextln: movdqu  64(%rsp), %xmm10
+    ; nextln: movdqu  80(%rsp), %xmm11
+    ; nextln: movdqu  96(%rsp), %xmm12
+    ; nextln: movdqu  112(%rsp), %xmm13
+    ; nextln: movdqu  128(%rsp), %xmm14
+    ; nextln: movdqu  144(%rsp), %xmm15
+    ; nextln: movq    160(%rsp), %rsi
+    ; nextln: movq    168(%rsp), %rdi
+    ; nextln: addq    $$176, %rsp
+    ; nextln: movq    %rbp, %rsp
+    ; nextln: popq    %rbp
+    ; nextln: ret
+    call_indirect sig0, v0()
+    return
+}
+
+function %many_args(
+    ;; rdi, rsi, rdx, rcx, r8, r9,
+    i64, i64, i64, i64, i64, i64,
+
+    ;; xmm0-7
+    f64, f64, f64, f64, f64, f64, f64, f64,
+
+    ;; stack args
+    i64, i32, f32, f64
+) system_v {
+    sig0 = (
+      i64, i64, i64, i64, i64, i64, f64, f64, f64, f64, f64, f64, f64, f64, i64,
+      i32, f32, f64
+    ) windows_fastcall
+block0(
+      v0: i64, v1:i64, v2:i64, v3:i64,
+      v4:i64, v5:i64,
+      v6: f64, v7: f64, v8:f64, v9:f64, v10:f64, v11:f64, v12:f64, v13:f64,
+      v14:i64, v15:i32, v16:f32, v17:f64
+):
+    ; check:  pushq   %rbp
+    ; nextln: movq    %rsp, %rbp
+    ; nextln: subq    $$32, %rsp
+    ; nextln: movq    %r12, 0(%rsp)
+    ; nextln: movq    %r13, 8(%rsp)
+    ; nextln: movq    %r14, 16(%rsp)
+    ; nextln: movq    %rdx, %rax
+    ; nextln: movq    %rcx, %r10
+    ; nextln: movq    %r8, %r11
+    ; nextln: movq    %r9, %r12
+    ; nextln: movq    16(%rbp), %r13
+    ; nextln: movslq  24(%rbp), %r14
+    ; nextln: movss   32(%rbp), %xmm8
+    ; nextln: movsd   40(%rbp), %xmm9
+    ; nextln: subq    $$144, %rsp
+    ; nextln: virtual_sp_offset_adjust 144
+    ; nextln: movq    %rdi, %rcx
+    ; nextln: movq    %rsi, %rdx
+    ; nextln: movq    %rax, %r8
+    ; nextln: movq    %r10, %r9
+    ; nextln: movq    %r11, 32(%rsp)
+    ; nextln: movq    %r12, 40(%rsp)
+    ; nextln: movsd   %xmm0, 48(%rsp)
+    ; nextln: movsd   %xmm1, 56(%rsp)
+    ; nextln: movsd   %xmm2, 64(%rsp)
+    ; nextln: movsd   %xmm3, 72(%rsp)
+    ; nextln: movsd   %xmm4, 80(%rsp)
+    ; nextln: movsd   %xmm5, 88(%rsp)
+    ; nextln: movsd   %xmm6, 96(%rsp)
+    ; nextln: movsd   %xmm7, 104(%rsp)
+    ; nextln: movq    %r13, 112(%rsp)
+    ; nextln: movl    %r14d, 120(%rsp)
+    ; nextln: movss   %xmm8, 128(%rsp)
+    ; nextln: movsd   %xmm9, 136(%rsp)
+    ; nextln: call    *%rdi
+    ; nextln: addq    $$144, %rsp
+    ; nextln: virtual_sp_offset_adjust -144
+    ; nextln: movq    0(%rsp), %r12
+    ; nextln: movq    8(%rsp), %r13
+    ; nextln: movq    16(%rsp), %r14
+    ; nextln: addq    $$32, %rsp
+    ; nextln: movq    %rbp, %rsp
+    ; nextln: popq    %rbp
+    ; nextln: ret
+    call_indirect sig0, v0(
+      v0, v1, v2, v3,
+      v4, v5, v6, v7,
+      v8, v9, v10, v11,
+      v12, v13, v14, v15,
+      v16, v17
+    )
+    return
+}
+
+; rdi => rcx
+; rsi => rdx
+; rdx => r8
+; rcx => r9
+; r8 => stack
+function %many_ints(i64, i64, i64, i64, i64) system_v {
+    sig0 = (i64, i64, i64, i64, i64) windows_fastcall
+block0(v0: i64, v1:i64, v2:i64, v3:i64, v4:i64):
+    ; check:  pushq   %rbp
+    ; nextln: movq    %rsp, %rbp
+    ; nextln: movq    %rdx, %rax
+    ; nextln: movq    %rcx, %r9
+    ; nextln: movq    %r8, %r10
+    ; nextln: subq    $$48, %rsp
+    ; nextln: virtual_sp_offset_adjust 48
+    ; nextln: movq    %rdi, %rcx
+    ; nextln: movq    %rsi, %rdx
+    ; nextln: movq    %rax, %r8
+    ; nextln: movq    %r10, 32(%rsp)
+    ; nextln: call    *%rdi
+    ; nextln: addq    $$48, %rsp
+    ; nextln: virtual_sp_offset_adjust -48
+    ; nextln: movq    %rbp, %rsp
+    ; nextln: popq    %rbp
+    ; nextln: ret
+    call_indirect sig0, v0(v0, v1, v2, v3, v4)
+    return
+}
+
+function %many_args2(i32, f32, i64, f64, i32, i32, i32, f32, f64, f32, f64) system_v {
+    sig0 = (i32, f32, i64, f64, i32, i32, i32, f32, f64, f32, f64) windows_fastcall
+block0(v0: i32, v1: f32, v2: i64, v3: f64, v4: i32, v5: i32, v6: i32, v7: f32, v8: f64, v9: f32, v10: f64):
+    ; check:   pushq   %rbp
+    ; nextln:  movq    %rsp, %rbp
+    ; nextln:  movaps  %xmm1, %xmm6
+    ; nextln:  movq    %rcx, %rax
+    ; nextln:  movq    %r8, %r9
+    ; nextln:  movaps  %xmm3, %xmm7
+    ; nextln:  subq    $$96, %rsp
+    ; nextln:  virtual_sp_offset_adjust 96
+    ; nextln:  movq    %rdi, %rcx
+    ; nextln:  movaps  %xmm0, %xmm1
+    ; nextln:  movq    %rsi, %r8
+    ; nextln:  movaps  %xmm6, %xmm3
+    ; nextln:  movl    %edx, 32(%rsp)
+    ; nextln:  movl    %eax, 40(%rsp)
+    ; nextln:  movl    %r9d, 48(%rsp)
+    ; nextln:  movss   %xmm2, 56(%rsp)
+    ; nextln:  movsd   %xmm7, 64(%rsp)
+    ; nextln:  movss   %xmm4, 72(%rsp)
+    ; nextln:  movsd   %xmm5, 80(%rsp)
+    ; nextln:  call    *%rdi
+    ; nextln:  addq    $$96, %rsp
+    ; nextln:  virtual_sp_offset_adjust -96
+    ; nextln:  movq    %rbp, %rsp
+    ; nextln:  popq    %rbp
+    ; nextln:  ret
+    call_indirect sig0, v0(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10)
+    return
+}