Index: llvm/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -4118,9 +4118,10 @@
 
   if (Subtarget.isPICStyleGOT()) {
     // ELF / PIC requires GOT in the EBX register before function calls via PLT
-    // GOT pointer.
+    // GOT pointer (except regcall).
     if (!isTailCall) {
-      RegsToPass.push_back(std::make_pair(
+      if (CallConv != CallingConv::X86_RegCall)
+        RegsToPass.push_back(std::make_pair(
           Register(X86::EBX), DAG.getNode(X86ISD::GlobalBaseReg, SDLoc(),
                                           getPointerTy(DAG.getDataLayout()))));
     } else {
Index: llvm/test/CodeGen/X86/x86-regcall-got.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/x86-regcall-got.ll
@@ -0,0 +1,63 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -O0 -mtriple=i386-unknown-linux-gnu -relocation-model=pic < %s | FileCheck %s
+
+; Unbind the ebx with GOT address in regcall calling convention, or the following
+; case will failed in register allocation by no register can be used.
+
+;//clang -target i386-unknown-linux-gnu -S -fpic t.c
+;#define REGCALL __attribute__((regcall))
+;int REGCALL func (int i1, int i2, int i3, int i4, int i5);
+;int (REGCALL *fptr) (int, int, int, int, int) = func;
+;int test() {
+;    return fptr(1,2,3,4,5);
+;}
+
+@fptr = global i32 (i32, i32, i32, i32, i32)* @__regcall3__func, align 4
+
+declare x86_regcallcc i32 @__regcall3__func(i32 inreg, i32 inreg, i32 inreg, i32 inreg, i32 inreg) #0
+
+; Function Attrs: noinline nounwind optnone
+define i32 @test() #1 {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    pushl %ebp
+; CHECK-NEXT:    movl %esp, %ebp
+; CHECK-NEXT:    pushl %ebx
+; CHECK-NEXT:    pushl %edi
+; CHECK-NEXT:    pushl %esi
+; CHECK-NEXT:    subl $12, %esp
+; CHECK-NEXT:    calll .L0$pb
+; CHECK-NEXT:  .L0$pb:
+; CHECK-NEXT:    popl %eax
+; CHECK-NEXT:  .Ltmp0:
+; CHECK-NEXT:    addl $_GLOBAL_OFFSET_TABLE_+(.Ltmp0-.L0$pb), %eax
+; CHECK-NEXT:    movl fptr@GOT(%eax), %eax
+; CHECK-NEXT:    movl (%eax), %ebx
+; CHECK-NEXT:    movl $1, %eax
+; CHECK-NEXT:    movl $2, %ecx
+; CHECK-NEXT:    movl $3, %edx
+; CHECK-NEXT:    movl $4, %edi
+; CHECK-NEXT:    movl $5, %esi
+; CHECK-NEXT:    calll *%ebx
+; CHECK-NEXT:    addl $12, %esp
+; CHECK-NEXT:    popl %esi
+; CHECK-NEXT:    popl %edi
+; CHECK-NEXT:    popl %ebx
+; CHECK-NEXT:    popl %ebp
+; CHECK-NEXT:    retl
+entry:
+  %0 = load i32 (i32, i32, i32, i32, i32)*, i32 (i32, i32, i32, i32, i32)** @fptr, align 4
+  %call = call x86_regcallcc i32 %0(i32 inreg 1, i32 inreg 2, i32 inreg 3, i32 inreg 4, i32 inreg 5)
+  ret i32 %call
+}
+
+attributes #0 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1, !2}
+!llvm.ident = !{!3}
+
+!0 = !{i32 1, !"NumRegisterParameters", i32 0}
+!1 = !{i32 1, !"wchar_size", i32 4}
+!2 = !{i32 7, !"PIC Level", i32 1}
+!3 = !{!"Intel(R) oneAPI DPC++ Compiler 2021.1 (YYYY.x.0.MMDD)"}