diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2996,7 +2996,6 @@
 
   Instruction *InsBefore = AllocaVec[0];
   IRBuilder<> IRB(InsBefore);
-  IRB.SetCurrentDebugLocation(EntryDebugLocation);
 
   // Make sure non-instrumented allocas stay in the entry block. Otherwise,
   // debug info is broken, because only entry-block allocas are treated as
@@ -3091,14 +3090,12 @@
     Instruction *Term =
         SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
     IRBuilder<> IRBIf(Term);
-    IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
     StackMallocIdx = StackMallocSizeClass(LocalStackSize);
     assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
     Value *FakeStackValue =
         IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
                          ConstantInt::get(IntptrTy, LocalStackSize));
     IRB.SetInsertPoint(InsBefore);
-    IRB.SetCurrentDebugLocation(EntryDebugLocation);
     FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
                           ConstantInt::get(IntptrTy, 0));
 
@@ -3106,14 +3103,11 @@
         IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
     Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
     IRBIf.SetInsertPoint(Term);
-    IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
     Value *AllocaValue =
         DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
 
     IRB.SetInsertPoint(InsBefore);
-    IRB.SetCurrentDebugLocation(EntryDebugLocation);
     LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
-    IRB.SetCurrentDebugLocation(EntryDebugLocation);
     IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
     DIExprFlags |= DIExpression::DerefBefore;
   } else {
diff --git a/llvm/test/Instrumentation/AddressSanitizer/debug-info-alloca.ll b/llvm/test/Instrumentation/AddressSanitizer/debug-info-alloca.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Instrumentation/AddressSanitizer/debug-info-alloca.ll
@@ -0,0 +1,75 @@
+; Checks that asan instrumentation does not include line numbers as debug information.
+; Line info in an instrumentation instruction within the prologue would fool findPrologueEndLoc
+; to set the end of the prologue before that instruction. Breaking on the instrumented function
+; in the debugger would then stop there, before the prologue has finished.
+
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+; 1: void f(int *arg) {
+; 2: }
+; 3: int main(int argc, char **argv) {
+; 4:   f(&argc);
+; 5: }
+; clang 1.cc -g -S -emit-llvm -o - | sed 's/#0 = {/#0 = { sanitize_address/'
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local i32 @main(i32 %argc, i8** %argv) #0 !dbg !15 {
+entry:
+; No suffix like !dbg !123
+; CHECK: %asan_local_stack_base = alloca i64{{$}}
+; CHECK:     %3 = call i64 @__asan_stack_malloc_0(i64 64){{$}}
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 8
+  store i32 %argc, i32* %argc.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %argc.addr, metadata !21, metadata !DIExpression()), !dbg !22
+  store i8** %argv, i8*** %argv.addr, align 8
+  call void @llvm.dbg.declare(metadata i8*** %argv.addr, metadata !23, metadata !DIExpression()), !dbg !24
+  call void @f(i32* %argc.addr), !dbg !25
+  ret i32 0, !dbg !26
+}
+
+define dso_local void @f(i32* %arg) #0 !dbg !7 {
+entry:
+  %arg.addr = alloca i32*, align 8
+  store i32* %arg, i32** %arg.addr, align 8
+  call void @llvm.dbg.declare(metadata i32** %arg.addr, metadata !12, metadata !DIExpression()), !dbg !13
+  ret void, !dbg !14
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { sanitize_address noinline nounwind optnone uwtable "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"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (git@github.com:llvm/llvm-project 1ac700cdef787383ad49a0e37d9894491ef19480)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "2.c", directory: "/home/builduser")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (git@github.com:llvm/llvm-project 1ac700cdef787383ad49a0e37d9894491ef19480)"}
+!7 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10}
+!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!13 = !DILocation(line: 1, column: 13, scope: !7)
+!14 = !DILocation(line: 2, column: 1, scope: !7)
+!15 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !16, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!16 = !DISubroutineType(types: !17)
+!17 = !{!11, !11, !18}
+!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
+!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !20, size: 64)
+!20 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!21 = !DILocalVariable(name: "argc", arg: 1, scope: !15, file: !1, line: 3, type: !11)
+!22 = !DILocation(line: 3, column: 14, scope: !15)
+!23 = !DILocalVariable(name: "argv", arg: 2, scope: !15, file: !1, line: 3, type: !18)
+!24 = !DILocation(line: 3, column: 27, scope: !15)
+!25 = !DILocation(line: 4, column: 3, scope: !15)
+!26 = !DILocation(line: 5, column: 1, scope: !15)
diff --git a/llvm/test/Instrumentation/AddressSanitizer/local_stack_base.ll b/llvm/test/Instrumentation/AddressSanitizer/local_stack_base.ll
--- a/llvm/test/Instrumentation/AddressSanitizer/local_stack_base.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/local_stack_base.ll
@@ -18,8 +18,8 @@
   ; CHECK: %asan_local_stack_base = alloca i64
   ; CHECK: %[[ALLOCA:.*]] = ptrtoint i8* %MyAlloca to i64
   ; CHECK: %[[PHI:.*]] = phi i64 {{.*}} %[[ALLOCA]],
-  ; CHECK: store i64 %[[PHI]], i64* %asan_local_stack_base, !dbg
-  ; CHECK: call void @llvm.dbg.declare(metadata i64* %asan_local_stack_base, metadata !13, metadata !DIExpression(DW_OP_deref, DW_OP_plus_uconst, 32)), !dbg !14
+  ; CHECK: store i64 %[[PHI]], i64* %asan_local_stack_base
+  ; CHECK: call void @llvm.dbg.declare(metadata i64* %asan_local_stack_base, metadata !12, metadata !DIExpression(DW_OP_deref, DW_OP_plus_uconst, 32)), !dbg !13
   %0 = load i32, i32* %i.addr, align 4, !dbg !14
   %add = add nsw i32 %0, 2, !dbg !15
   ret i32 %add, !dbg !16