Index: include/llvm/CodeGen/FastISel.h
===================================================================
--- include/llvm/CodeGen/FastISel.h
+++ include/llvm/CodeGen/FastISel.h
@@ -226,6 +226,9 @@
   /// be appended, and clear the local CSE map.
   void startNewBlock();
 
+  /// \brief Performs post-processing of complete basic block.
+  void finishBasicBlock();
+
   /// \brief Return current debug location information.
   DebugLoc getCurDebugLoc() const { return DbgLoc; }
 
@@ -569,6 +572,11 @@
   bool lowerCallOperands(const CallInst *CI, unsigned ArgIdx, unsigned NumArgs,
                          const Value *Callee, bool ForceRetVoidTy,
                          CallLoweringInfo &CLI);
+
+  /// \brief Copies first non-empty debug location from list of instructions as
+  /// starting location for current block.
+  /// \param BlockFinished Whether whole block was processed at this point.
+  void fixupLocalValueLocations(bool BlockFinished);
 };
 
 } // end namespace llvm
Index: lib/CodeGen/SelectionDAG/FastISel.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/FastISel.cpp
+++ lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -104,6 +104,48 @@
   LastLocalValue = EmitStartPt;
 }
 
+void FastISel::finishBasicBlock() {
+  fixupLocalValueLocations(true);
+}
+
+void FastISel::fixupLocalValueLocations(bool BlockFinished) {
+  bool IsEntryBlock =
+      (FuncInfo.MBB == FuncInfo.MBBMap[&FuncInfo.Fn->getEntryBlock()]);
+
+  // If this is the wrap-up stage of block processing, and any local-value
+  // instructions are _not_ at the very beginning of the block, then we should
+  // _not_ update their debug info.
+  //
+  // Skip entry basic block to do not move "prologue_end" location above stack
+  // adjustment.
+  if (BlockFinished && (EmitStartPt || IsEntryBlock))
+    return;
+
+  // Nothing to do if we didn't emit any local values.
+  if (LocalValueMap.empty())
+    return;
+
+  // Find first local value.
+  MachineBasicBlock::iterator FirstLocalValue;
+  if (EmitStartPt) {
+    FirstLocalValue = EmitStartPt;
+    ++FirstLocalValue;
+  } else {
+    FirstLocalValue = FuncInfo.MBB->begin();
+    // Skip past any EH_LABELs, which go before local values.
+    while (FirstLocalValue->getOpcode() == TargetOpcode::EH_LABEL)
+      ++FirstLocalValue;
+  }
+
+  // Find first instruction with non-null debug location.
+  MachineBasicBlock::iterator InstWithLoc = FuncInfo.InsertPt;
+  while (InstWithLoc != FuncInfo.MBB->end() && !InstWithLoc->getDebugLoc())
+    ++InstWithLoc;
+
+  if (InstWithLoc != FuncInfo.MBB->end())
+    FirstLocalValue->setDebugLoc(InstWithLoc->getDebugLoc());
+}
+
 bool FastISel::lowerArguments() {
   if (!FuncInfo.CanLowerReturn)
     // Fallback to SDISel argument lowering code to deal with sret pointer
@@ -125,6 +167,7 @@
 }
 
 void FastISel::flushLocalValueMap() {
+  fixupLocalValueLocations(false);
   LocalValueMap.clear();
   LastLocalValue = EmitStartPt;
   recomputeInsertPt();
Index: lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1312,6 +1312,8 @@
     }
 
     FinishBasicBlock();
+    if (FastIS)
+      FastIS->finishBasicBlock();
     FuncInfo->PHINodesToUpdate.clear();
   }
 
Index: test/DebugInfo/ARM/single-constant-use-preserves-dbgloc.ll
===================================================================
--- test/DebugInfo/ARM/single-constant-use-preserves-dbgloc.ll
+++ test/DebugInfo/ARM/single-constant-use-preserves-dbgloc.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -filetype=asm -asm-verbose=0 < %s | FileCheck %s
+; RUN: llc -fast-isel -filetype=asm -asm-verbose=0 < %s | FileCheck %s
 
 ; int main()
 ; {
Index: test/DebugInfo/X86/dbg-line-fast-isel.ll
===================================================================
--- /dev/null
+++ test/DebugInfo/X86/dbg-line-fast-isel.ll
@@ -0,0 +1,104 @@
+; RUN: llc -disable-fp-elim -O0 %s -o - | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; int callme(int);
+;
+; int isel_line_test(int arg)
+; {
+;   callme(100);
+;   if (arg > 5000)
+;     callme(200);
+;   callme(300);
+;   return 0;
+; }
+;
+; int isel_line_test2()
+; {
+;   callme(400);
+;   return 0;
+; }
+
+
+; Function Attrs: nounwind uwtable
+define i32 @isel_line_test(i32 %arg) #0 {
+; The start of each non-entry block (or sub-block) should get a .loc directive.
+; CHECK:       isel_line_test:
+; CHECK:       # BB#1:
+; CHECK-NEXT:  .loc 1 7 5
+; CHECK:       LBB0_2:
+; CHECK-NEXT:  .loc 1 8 3
+; CHECK:       callq callme
+; CHECK-NEXT:  .loc 1 9 3
+
+entry:
+  %arg.addr = alloca i32, align 4
+  store i32 %arg, i32* %arg.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %arg.addr, metadata !14, metadata !15), !dbg !16
+  %call = call i32 @callme(i32 100), !dbg !17
+  %0 = load i32, i32* %arg.addr, align 4, !dbg !18
+  %cmp = icmp sgt i32 %0, 5000, !dbg !20
+  br i1 %cmp, label %if.then, label %if.end, !dbg !21
+
+if.then:                                          ; preds = %entry
+  %call1 = call i32 @callme(i32 200), !dbg !22
+  br label %if.end, !dbg !22
+
+if.end:                                           ; preds = %if.then, %entry
+  %call2 = call i32 @callme(i32 300), !dbg !23
+  ret i32 0, !dbg !24
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+declare i32 @callme(i32) #2
+
+; Function Attrs: nounwind uwtable
+define i32 @isel_line_test2() #0 {
+; The stack adjustment should be part of the prologue.
+; CHECK: isel_line_test2:
+; CHECK: subq {{.*}}, %rsp
+; CHECK: .loc 1 14 3 prologue_end
+
+entry:
+  %call = call i32 @callme(i32 400), !dbg !25
+  ret i32 0, !dbg !26
+}
+
+attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!11, !12}
+!llvm.ident = !{!13}
+
+!0 = !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.7.0 (http://llvm.org/git/clang.git 9a7bb3c6dbb127c006460290f702f93299eadc24) (http://llvm.org/git/llvm.git 91a675f9727e14a8339c192c6d2dffc4f5dd46b5)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
+!1 = !DIFile(filename: "dbg-line-fast-isel.c", directory: "/build")
+!2 = !{}
+!3 = !{!4, !8}
+!4 = !DISubprogram(name: "isel_line_test", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: false, function: i32 (i32)* @isel_line_test, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = !DISubprogram(name: "isel_line_test2", scope: !1, file: !1, line: 12, type: !9, isLocal: false, isDefinition: true, scopeLine: 13, isOptimized: false, function: i32 ()* @isel_line_test2, variables: !2)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!7}
+!11 = !{i32 2, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{!"clang version 3.7.0 (http://llvm.org/git/clang.git 9a7bb3c6dbb127c006460290f702f93299eadc24) (http://llvm.org/git/llvm.git 91a675f9727e14a8339c192c6d2dffc4f5dd46b5)"}
+!14 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "arg", arg: 1, scope: !4, file: !1, line: 3, type: !7)
+!15 = !DIExpression()
+!16 = !DILocation(line: 3, column: 24, scope: !4)
+!17 = !DILocation(line: 5, column: 3, scope: !4)
+!18 = !DILocation(line: 6, column: 7, scope: !19)
+!19 = distinct !DILexicalBlock(scope: !4, file: !1, line: 6, column: 7)
+!20 = !DILocation(line: 6, column: 11, scope: !19)
+!21 = !DILocation(line: 6, column: 7, scope: !4)
+!22 = !DILocation(line: 7, column: 5, scope: !19)
+!23 = !DILocation(line: 8, column: 3, scope: !4)
+!24 = !DILocation(line: 9, column: 3, scope: !4)
+!25 = !DILocation(line: 14, column: 3, scope: !8)
+!26 = !DILocation(line: 15, column: 3, scope: !8)