Index: lib/Target/SystemZ/SystemZAsmPrinter.cpp
===================================================================
--- lib/Target/SystemZ/SystemZAsmPrinter.cpp
+++ lib/Target/SystemZ/SystemZAsmPrinter.cpp
@@ -210,6 +210,12 @@
     break;
 
   case SystemZ::CallBRASL:
+    if (MF->getFunction().getFnAttribute("mnop-mcount")
+                         .getValueAsString() == "true" &&
+        MI->getOperand(0).isGlobal() &&
+        MI->getOperand(0).getGlobal()->getName().str().compare("mcount") == 0)
+      report_fatal_error("-mnop-mcount only supported for fentry");
+
     LoweredMI = MCInstBuilder(SystemZ::BRASL)
       .addReg(SystemZ::R14D)
       .addExpr(Lower.getExpr(MI->getOperand(0), MCSymbolRefExpr::VK_PLT));
@@ -553,6 +559,12 @@
 void SystemZAsmPrinter::LowerFENTRY_CALL(const MachineInstr &MI,
                                          SystemZMCInstLower &Lower) {
   MCContext &Ctx = MF->getContext();
+  if (MF->getFunction().getFnAttribute("mnop-mcount")
+                       .getValueAsString() == "true") {
+    EmitNop(Ctx, *OutStreamer, 6, getSubtargetInfo());
+    return;
+  }
+
   MCSymbol *fentry = Ctx.getOrCreateSymbol("__fentry__");
   const MCSymbolRefExpr *Op =
       MCSymbolRefExpr::create(fentry, MCSymbolRefExpr::VK_PLT, Ctx);
Index: test/CodeGen/SystemZ/mnop-mcount-01.ll
===================================================================
--- /dev/null
+++ test/CodeGen/SystemZ/mnop-mcount-01.ll
@@ -0,0 +1,26 @@
+; RUN: llc %s -mtriple=s390x-linux-gnu -mcpu=z10 -o - -verify-machineinstrs \
+; RUN:   | FileCheck %s
+
+define void @test1() #0 {
+entry:
+  ret void
+
+; CHECK-LABEL: @test1
+; CHECK: brasl %r0, __fentry__
+; CHECK-NOT: brcl 0, .Ltmp0
+; CHECK: br %r14
+}
+
+define void @test2() #1 {
+entry:
+  ret void
+
+; CHECK-LABEL: @test2
+; CHECK-NOT: brasl %r0, __fentry__
+; CHECK: brcl 0, .Ltmp0
+; CHECK: br %r14
+}
+
+attributes #0 = { "fentry-call"="true" }
+attributes #1 = { "fentry-call"="true" "mnop-mcount"="true" }
+
Index: test/CodeGen/SystemZ/mnop-mcount-02.ll
===================================================================
--- /dev/null
+++ test/CodeGen/SystemZ/mnop-mcount-02.ll
@@ -0,0 +1,11 @@
+; RUN: not llc %s -mtriple=s390x-linux-gnu -o - 2>&1 | FileCheck %s
+;
+; CHECK: LLVM ERROR: -mnop-mcount only supported for fentry
+
+define void @test1() #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { "instrument-function-entry-inlined"="mcount" "mnop-mcount"="true" }
+