Index: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2801,26 +2801,24 @@
   }
 
   // Before we switch over, we force a reference to a label inside the
-  // xray_instr_map and xray_fn_idx sections. Since this function is always
-  // called just before the function's end, we assume that this is happening
-  // after the last return instruction. We also use the synthetic label in the
-  // xray_inster_map as a delimeter for the range of sleds for this function in
-  // the index.
+  // xray_fn_idx sections. This makes sure that the xray_fn_idx section is kept
+  // live by the linker if the function is not garbage-collected. Since this
+  // function is always called just before the function's end, we assume that
+  // this is happening after the last return instruction.
   auto WordSizeBytes = MAI->getCodePointerSize();
-  MCSymbol *SledsStart = OutContext.createTempSymbol("xray_synthetic_", true);
   MCSymbol *IdxRef = OutContext.createTempSymbol("xray_fn_idx_synth_", true);
   OutStreamer->EmitCodeAlignment(16);
-  OutStreamer->EmitSymbolValue(SledsStart, WordSizeBytes, false);
   OutStreamer->EmitSymbolValue(IdxRef, WordSizeBytes, false);
 
   // Now we switch to the instrumentation map section. Because this is done
   // per-function, we are able to create an index entry that will represent the
   // range of sleds associated with a function.
+  MCSymbol *SledsStart = OutContext.createTempSymbol("xray_sleds_start", true);
   OutStreamer->SwitchSection(InstMap);
   OutStreamer->EmitLabel(SledsStart);
   for (const auto &Sled : Sleds)
     Sled.emit(WordSizeBytes, OutStreamer.get(), CurrentFnSym);
-  MCSymbol *SledsEnd = OutContext.createTempSymbol("xray_synthetic_end", true);
+  MCSymbol *SledsEnd = OutContext.createTempSymbol("xray_sleds_end", true);
   OutStreamer->EmitLabel(SledsEnd);
 
   // We then emit a single entry in the index per function. We use the symbols
Index: llvm/trunk/test/CodeGen/AArch64/xray-attribute-instrumentation.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/xray-attribute-instrumentation.ll
+++ llvm/trunk/test/CodeGen/AArch64/xray-attribute-instrumentation.ll
@@ -25,9 +25,9 @@
 ; CHECK-NEXT:  ret
 }
 ; CHECK:       .p2align 4
-; CHECK-NEXT:  .xword .Lxray_synthetic_0
 ; CHECK-NEXT:  .xword .Lxray_fn_idx_synth_0
 ; CHECK-NEXT:  .section xray_instr_map,{{.*}}
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0
 ; CHECK:       .xword .Lxray_sled_0
 ; CHECK:       .xword .Lxray_sled_1
+; CHECK-LABEL: Lxray_sleds_end0
Index: llvm/trunk/test/CodeGen/AArch64/xray-tail-call-sled.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/xray-tail-call-sled.ll
+++ llvm/trunk/test/CodeGen/AArch64/xray-tail-call-sled.ll
@@ -28,21 +28,20 @@
 ; CHECK-NEXT:  ret
 }
 ; CHECK:       .p2align 4
-; CHECK-NEXT:  .xword .Lxray_synthetic_0
 ; CHECK-NEXT:  .xword .Lxray_fn_idx_synth_0
 ; CHECK-NEXT:  .section xray_instr_map,{{.*}}
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .xword .Lxray_sled_0
 ; CHECK:       .xword .Lxray_sled_1
-; CHECK-LABEL: Lxray_synthetic_end0:
+; CHECK-LABEL: Lxray_sleds_end0:
 ; CHECK:       .section xray_fn_idx,{{.*}}
 ; CHECK-LABEL: Lxray_fn_idx_synth_0:
-; CHECK:       .xword .Lxray_synthetic_0
-; CHECK-NEXT:  .xword .Lxray_synthetic_end0
+; CHECK:       .xword .Lxray_sleds_start0
+; CHECK-NEXT:  .xword .Lxray_sleds_end0
 
 define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-always" {
 ; CHECK:       .p2align	2
-; CHECK-LABEL: .Lxray_sled_2:
+; CHECK-LABEL: Lxray_sled_2:
 ; CHECK-NEXT:  b	#32
 ; CHECK-NEXT:  nop
 ; CHECK-NEXT:  nop
@@ -53,7 +52,7 @@
 ; CHECK-NEXT:  nop
 ; CHECK-LABEL: .Ltmp2:
 ; CHECK:       .p2align	2
-; CHECK-LABEL: .Lxray_sled_3:
+; CHECK-LABEL: Lxray_sled_3:
 ; CHECK-NEXT:  b	#32
 ; CHECK-NEXT:  nop
 ; CHECK-NEXT:  nop
@@ -68,14 +67,13 @@
   ret i32 %retval
 }
 ; CHECK:       .p2align 4
-; CHECK-NEXT:  .xword .Lxray_synthetic_1
 ; CHECK-NEXT:  .xword .Lxray_fn_idx_synth_1
 ; CHECK-NEXT:  .section xray_instr_map,{{.*}}
-; CHECK-LABEL: Lxray_synthetic_1:
+; CHECK-LABEL: Lxray_sleds_start1:
 ; CHECK:       .xword .Lxray_sled_2
 ; CHECK:       .xword .Lxray_sled_3
-; CHECK-LABEL: Lxray_synthetic_end1:
+; CHECK-LABEL: Lxray_sleds_end1:
 ; CHECK:       .section xray_fn_idx,{{.*}}
 ; CHECK-LABEL: Lxray_fn_idx_synth_1:
-; CHECK:       .xword .Lxray_synthetic_1
-; CHECK-NEXT:  .xword .Lxray_synthetic_end1
+; CHECK:       .xword .Lxray_sleds_start1
+; CHECK-NEXT:  .xword .Lxray_sleds_end1
Index: llvm/trunk/test/CodeGen/ARM/xray-armv6-attribute-instrumentation.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/xray-armv6-attribute-instrumentation.ll
+++ llvm/trunk/test/CodeGen/ARM/xray-armv6-attribute-instrumentation.ll
@@ -24,14 +24,13 @@
 ; CHECK-NEXT:  bx	lr
 }
 ; CHECK:       .p2align 4
-; CHECK-NEXT:  .long {{.*}}Lxray_synthetic_0
 ; CHECK-NEXT:  .long {{.*}}Lxray_fn_idx_synth_0
 ; CHECK-NEXT:  .section {{.*}}xray_instr_map{{.*}}
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .long {{.*}}Lxray_sled_0
 ; CHECK:       .long {{.*}}Lxray_sled_1
-; CHECK-LABEL: Lxray_synthetic_end0:
+; CHECK-LABEL: Lxray_sleds_end0:
 ; CHECK:       .section {{.*}}xray_fn_idx{{.*}}
 ; CHECK-LABEL: Lxray_fn_idx_synth_0:
-; CHECK:       .long {{.*}}Lxray_synthetic_0
-; CHECK-NEXT:  .long {{.*}}Lxray_synthetic_end0
+; CHECK:       .long {{.*}}Lxray_sleds_start0
+; CHECK-NEXT:  .long {{.*}}Lxray_sleds_end0
Index: llvm/trunk/test/CodeGen/ARM/xray-armv7-attribute-instrumentation.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/xray-armv7-attribute-instrumentation.ll
+++ llvm/trunk/test/CodeGen/ARM/xray-armv7-attribute-instrumentation.ll
@@ -24,15 +24,14 @@
 ; CHECK-NEXT:  bx lr
 }
 ; CHECK:       .p2align 4
-; CHECK-NEXT:  .long {{.*}}Lxray_synthetic_0
 ; CHECK-NEXT:  .long {{.*}}Lxray_fn_idx_synth_0
 ; CHECK-NEXT:  .section {{.*}}xray_instr_map{{.*}}
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .long {{.*}}Lxray_sled_0
 ; CHECK:       .long {{.*}}Lxray_sled_1
-; CHECK-LABEL: Lxray_synthetic_end0:
+; CHECK-LABEL: Lxray_sleds_end0:
 ; CHECK:       .section {{.*}}xray_fn_idx{{.*}}
 ; CHECK-LABEL: Lxray_fn_idx_synth_0:
-; CHECK:       .long {{.*}}xray_synthetic_0
-; CHECK-NEXT:  .long {{.*}}xray_synthetic_end0
+; CHECK:       .long {{.*}}xray_sleds_start0
+; CHECK-NEXT:  .long {{.*}}xray_sleds_end0
 
Index: llvm/trunk/test/CodeGen/X86/xray-attribute-instrumentation.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/xray-attribute-instrumentation.ll
+++ llvm/trunk/test/CodeGen/X86/xray-attribute-instrumentation.ll
@@ -14,17 +14,16 @@
 ; CHECK-NEXT:  nopw %cs:512(%rax,%rax)
 }
 ; CHECK:       .p2align 4, 0x90
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_0
 ; CHECK-NEXT:  .quad {{.*}}xray_fn_idx_synth_0
 ; CHECK-NEXT:  .section {{.*}}xray_instr_map
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .quad {{.*}}xray_sled_0
 ; CHECK:       .quad {{.*}}xray_sled_1
-; CHECK-LABEL: Lxray_synthetic_end0:
+; CHECK-LABEL: Lxray_sleds_end0:
 ; CHECK:       .section {{.*}}xray_fn_idx
 ; CHECK-LABEL: Lxray_fn_idx_synth_0:
-; CHECK:       .quad {{.*}}xray_synthetic_0
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_end0
+; CHECK:       .quad {{.*}}xray_sleds_start0
+; CHECK-NEXT:  .quad {{.*}}xray_sleds_end0
 
 
 ; We test multiple returns in a single function to make sure we're getting all
@@ -52,15 +51,14 @@
 ; CHECK-NEXT:  nopw %cs:512(%rax,%rax)
 }
 ; CHECK:       .p2align 4, 0x90
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_1
 ; CHECK-NEXT:  .quad {{.*}}xray_fn_idx_synth_1
 ; CHECK-NEXT:  .section {{.*}}xray_instr_map
-; CHECK-LABEL: Lxray_synthetic_1:
+; CHECK-LABEL: Lxray_sleds_start1:
 ; CHECK:       .quad {{.*}}xray_sled_2
 ; CHECK:       .quad {{.*}}xray_sled_3
 ; CHECK:       .quad {{.*}}xray_sled_4
-; CHECK-LABEL: Lxray_synthetic_end1:
+; CHECK-LABEL: Lxray_sleds_end1:
 ; CHECK:       .section {{.*}}xray_fn_idx
 ; CHECK-LABEL: Lxray_fn_idx_synth_1:
-; CHECK:       .quad {{.*}}xray_synthetic_1
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_end1
+; CHECK:       .quad {{.*}}xray_sleds_start1
+; CHECK-NEXT:  .quad {{.*}}xray_sleds_end1
Index: llvm/trunk/test/CodeGen/X86/xray-custom-log.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/xray-custom-log.ll
+++ llvm/trunk/test/CodeGen/X86/xray-custom-log.ll
@@ -17,7 +17,7 @@
     ret i32 0
 }
 ; CHECK:       .section {{.*}}xray_instr_map
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .quad {{.*}}xray_event_sled_0
 
 declare void @llvm.xray.customevent(i8*, i32)
Index: llvm/trunk/test/CodeGen/X86/xray-log-args.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/xray-log-args.ll
+++ llvm/trunk/test/CodeGen/X86/xray-log-args.ll
@@ -6,7 +6,7 @@
 define i32 @callee(i32 %arg) nounwind noinline uwtable "function-instrument"="xray-always" "xray-log-args"="1" {
   ret i32 %arg
 }
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:	.quad	{{\.?}}Lxray_sled_0
 ; CHECK:	.quad	{{_?}}callee
 ; CHECK:	.byte	3
@@ -22,7 +22,7 @@
   %retval = tail call i32 @callee(i32 %arg)
   ret i32 %retval
 }
-; CHECK-LABEL: Lxray_synthetic_1:
+; CHECK-LABEL: Lxray_sleds_start1:
 ; CHECK:	.quad	{{\.?}}Lxray_sled_2
 ; CHECK:	.quad	{{_?}}caller
 ; CHECK:	.byte	3
Index: llvm/trunk/test/CodeGen/X86/xray-tail-call-sled.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/xray-tail-call-sled.ll
+++ llvm/trunk/test/CodeGen/X86/xray-tail-call-sled.ll
@@ -14,17 +14,16 @@
 ; CHECK-NEXT:  nopw %cs:512(%rax,%rax)
 }
 ; CHECK:       .p2align 4, 0x90
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_0{{.*}}
 ; CHECK-NEXT:  .quad {{.*}}xray_fn_idx_synth_0{{.*}}
 ; CHECK-NEXT:  .section {{.*}}xray_instr_map
-; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK-LABEL: Lxray_sleds_start0:
 ; CHECK:       .quad {{.*}}xray_sled_0
 ; CHECK:       .quad {{.*}}xray_sled_1
-; CHECK-LABEL: Lxray_synthetic_end0:
+; CHECK-LABEL: Lxray_sleds_end0:
 ; CHECK-NEXT:  .section {{.*}}xray_fn_idx
 ; CHECK-LABEL: Lxray_fn_idx_synth_0:
-; CHECK:       .quad {{.*}}xray_synthetic_0
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_end0
+; CHECK:       .quad {{.*}}xray_sleds_start0
+; CHECK-NEXT:  .quad {{.*}}xray_sleds_end0
 
 define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-always" {
 ; CHECK:       .p2align 1, 0x90
@@ -42,13 +41,12 @@
   ret i32 %retval
 }
 ; CHECK:       .p2align 4, 0x90
-; CHECK-NEXT:  .quad {{.*}}xray_synthetic_1{{.*}}
 ; CHECK-NEXT:  .quad {{.*}}xray_fn_idx_synth_1{{.*}}
-; CHECK-LABEL: Lxray_synthetic_1:
+; CHECK-LABEL: Lxray_sleds_start1:
 ; CHECK:       .quad {{.*}}xray_sled_2
 ; CHECK:       .quad {{.*}}xray_sled_3
-; CHECK-LABEL: Lxray_synthetic_end1:
+; CHECK-LABEL: Lxray_sleds_end1:
 ; CHECK:       .section {{.*}}xray_fn_idx
 ; CHECK-LABEL: Lxray_fn_idx_synth_1:
-; CHECK:       .quad {{.*}}xray_synthetic_1
-; CHECK:       .quad {{.*}}xray_synthetic_end1
+; CHECK:       .quad {{.*}}xray_sleds_start1
+; CHECK:       .quad {{.*}}xray_sleds_end1