diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go
index 02e4c94c3a..3e5e2bf6bb 100644
--- a/src/cmd/internal/dwarf/dwarf.go
+++ b/src/cmd/internal/dwarf/dwarf.go
@@ -1207,6 +1207,12 @@ func PutAbstractFunc(ctxt Context, s *FnState) error {
 	return nil
 }
 
+// dwarfFileIndex returns the DWARF file index value for the file associated
+// with pos.
+func dwarfFileIndex(pos src.Pos) int64 {
+	return int64(1 + pos.FileIndex())
+}
+
 // Emit DWARF attributes and child DIEs for an inlined subroutine. The
 // first attribute of an inlined subroutine DIE is a reference back to
 // its corresponding 'abstract' DIE (containing location-independent
@@ -1240,7 +1246,7 @@ func putInlinedFunc(ctxt Context, s *FnState, callIdx int) error {
 	}
 
 	// Emit call file, line attrs.
-	putattr(ctxt, s.Info, abbrev, DW_FORM_data4, DW_CLS_CONSTANT, int64(1+ic.CallPos.FileIndex()), nil) // 1-based file table
+	putattr(ctxt, s.Info, abbrev, DW_FORM_data4, DW_CLS_CONSTANT, dwarfFileIndex(ic.CallPos), nil)
 	form := int(expandPseudoForm(DW_FORM_udata_pseudo))
 	putattr(ctxt, s.Info, abbrev, form, DW_CLS_CONSTANT, int64(ic.CallPos.RelLine()), nil)
 
@@ -1343,7 +1349,7 @@ func PutDefaultFunc(ctxt Context, s *FnState, isWrapper bool) error {
 	if isWrapper {
 		putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, int64(1), 0)
 	} else {
-		putattr(ctxt, s.Info, abbrev, DW_FORM_data4, DW_CLS_CONSTANT, int64(1+s.StartPos.FileIndex()), nil) // 1-based file index
+		putattr(ctxt, s.Info, abbrev, DW_FORM_data4, DW_CLS_CONSTANT, dwarfFileIndex(s.StartPos), nil)
 		putattr(ctxt, s.Info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(s.StartPos.RelLine()), nil)
 
 		var ev int64
diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index b653e09a3c..eb439ec923 100644
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1212,18 +1212,70 @@ func expandFile(fname string) string {
 
 // writeDirFileTables emits the portion of the DWARF line table
 // prologue containing the include directories and file names,
-// described in section 6.2.4 of the DWARF 4 standard. It walks the
+// described in section 6.2.4 of the DWARF standard. It walks the
 // filepaths for the unit to discover any common directories, which
 // are emitted to the directory table first, then the file table is
 // emitted after that.
+//
+// Note that there are some differences betwen DWARF versions 4 and 5
+// regarding how files and directories are handled; the chief item is
+// that in version 4 we have an implicit directory index 0 that holds
+// the compilation dir, and an implicit file index 0 that holds the
+// "primary" source file being compiled (with the assumption that
+// we'll get these two pieces of info from attributes on the
+// compilation unit DIE). DWARF version 5 does away with these
+// implicit entries; if you want to refer to a file or dir, you have
+// to mention it explicitly.
+//
+// So, let's say we have a Go package with import path
+// "github.com/fruit/bowl" with two source files, "apple.go" and
+// "orange.go". The directory and file table in version 4 might look
+// like:
+//
+//	Dir Table:
+//	1		github.com/fruit/bowl
+//
+//	File Table:
+//	Entry	Dir	Time	Size	Name
+//	1		0	0		0		<autogenerated>
+//	2		1	0		0		apple.go
+//	3		1	0		0		orange.go
+//
+// With DWARF version 5, the file and directory tables might look like
+//
+//	Dir Table:
+//	0		.
+//	1		github.com/fruit/bowl
+//
+//	File Table:
+//	Entry	Dir	  Name
+//	0		0	  ?                /* see remark below about this entry */
+//	1		0	  <autogenerated>
+//	2		1	  apple.go
+//	3		1	  orange.go
+//
+// Also worth noting that the line table prolog allows you to control
+// what items or fields appear in file and die entries (as opposed
+// to the fixed dir/time/size/name format for files in DWARF 4).
 func (d *dwctxt) writeDirFileTables(unit *sym.CompilationUnit, lsu *loader.SymbolBuilder) {
 	type fileDir struct {
 		base string
 		dir  int
 	}
 	dirNums := make(map[string]int)
-	dirs := []string{""}
+	dirs := []string{"."}
+	dirNums["."] = 0
 	files := []fileDir{}
+	if buildcfg.Experiment.Dwarf5 {
+		// Add a dummy zero entry (not used for anything) so as to
+		// ensure that the first useful file index is 1, since that's
+		// the default value of the line table file register).  Note
+		// the "?"; this was originally an empty string, but doing
+		// this triggers crashes in some versions of GDB, see
+		// https://sourceware.org/bugzilla/show_bug.cgi?id=30357 for
+		// the details.
+		files = append(files, fileDir{base: "?", dir: 0})
+	}
 
 	// Preprocess files to collect directories. This assumes that the
 	// file table is already de-duped.
@@ -1241,7 +1293,7 @@ func (d *dwctxt) writeDirFileTables(unit *sym.CompilationUnit, lsu *loader.Symbo
 		dir := path.Dir(name)
 		dirIdx, ok := dirNums[dir]
 		if !ok && dir != "." {
-			dirIdx = len(dirNums) + 1
+			dirIdx = len(dirNums)
 			dirNums[dir] = dirIdx
 			dirs = append(dirs, dir)
 		}
@@ -1260,22 +1312,61 @@ func (d *dwctxt) writeDirFileTables(unit *sym.CompilationUnit, lsu *loader.Symbo
 		}
 	}
 
-	// Emit directory section. This is a series of nul terminated
-	// strings, followed by a single zero byte.
 	lsDwsym := dwSym(lsu.Sym())
-	for k := 1; k < len(dirs); k++ {
-		d.AddString(lsDwsym, dirs[k])
-	}
-	lsu.AddUint8(0) // terminator
+	if buildcfg.Experiment.Dwarf5 {
+		// Emit DWARF5 directory and file sections. The key added
+		// element here for version 5 is that we emit a small prolog
+		// describing the format of each file/dir entry, then a count
+		// of the entries, then the entries themselves.
 
-	// Emit file section.
-	for k := 0; k < len(files); k++ {
-		d.AddString(lsDwsym, files[k].base)
-		dwarf.Uleb128put(d, lsDwsym, int64(files[k].dir))
-		lsu.AddUint8(0) // mtime
-		lsu.AddUint8(0) // length
+		// Dir table first...
+		lsu.AddUint8(1) // directory_entry_format_count
+		// each directory entry is just a single path string.
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_LNCT_path)
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_FORM_string)
+		// emit count, then dirs
+		dwarf.Uleb128put(d, lsDwsym, int64(len(dirs)))
+		for k := 0; k < len(dirs); k++ {
+			d.AddString(lsDwsym, dirs[k])
+		}
+
+		// ... now file table.  With DWARF version 5 we put out a
+		// prolog that describes the format of each file entry; our
+		// chosen format is a pair <F,D> where F is the file and D is
+		// the dir index (zero-based).
+		lsu.AddUint8(2) // file_entry_format_count
+		// each file entry is just a file path followed by dir index.
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_LNCT_path)
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_FORM_string)
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_LNCT_directory_index)
+		dwarf.Uleb128put(d, lsDwsym, dwarf.DW_FORM_udata)
+		// emit count, then files
+		dwarf.Uleb128put(d, lsDwsym, int64(len(files)))
+		for k := 0; k < len(files); k++ {
+			d.AddString(lsDwsym, files[k].base)
+			dwarf.Uleb128put(d, lsDwsym, int64(files[k].dir))
+		}
+	} else {
+		// Emit DWARF4 directory and file sections.
+
+		// Dir table first. This just a series of nul terminated
+		// strings, followed by a single zero byte.
+		for k := 1; k < len(dirs); k++ {
+			d.AddString(lsDwsym, dirs[k])
+		}
+		lsu.AddUint8(0) // terminator needed in V4 case.
+
+		// File table next. This is a series of
+		// file/dirindex/mtime/length tuples (where dirindex is
+		// 1-based) followed by a single zero byte.
+		for k := 0; k < len(files); k++ {
+			d.AddString(lsDwsym, files[k].base)
+			dwarf.Uleb128put(d, lsDwsym, int64(files[k].dir))
+			lsu.AddUint8(0) // mtime
+			lsu.AddUint8(0) // length
+		}
+		lsu.AddUint8(0) // terminator
 	}
-	lsu.AddUint8(0) // terminator
 }
 
 // writelines collects up and chains together the symbols needed to
@@ -1304,13 +1395,23 @@ func (d *dwctxt) writelines(unit *sym.CompilationUnit, lineProlog loader.Sym) []
 	unitLengthOffset := lsu.Size()
 	d.createUnitLength(lsu, 0) // unit_length (*), filled in at end
 	unitstart = lsu.Size()
-	lsu.AddUint16(d.arch, 2) // dwarf version (appendix F) -- version 3 is incompatible w/ XCode 9.0's dsymutil, latest supported on OSX 10.12 as of 2018-05
+	if buildcfg.Experiment.Dwarf5 {
+		lsu.AddUint16(d.arch, 5)
+		// DWARF5 requires address_size and segment selector sizes
+		// here, both ubyte format.
+		lsu.AddUint8(uint8(d.arch.PtrSize))
+		lsu.AddUint8(0)
+	} else {
+		lsu.AddUint16(d.arch, 2) // dwarf version (appendix F) -- version 3 is incompatible w/ XCode 9.0's dsymutil, latest supported on OSX 10.12 as of 2018-05
+	}
 	headerLengthOffset := lsu.Size()
 	d.addDwarfAddrField(lsu, 0) // header_length (*), filled in at end
 	headerstart = lsu.Size()
 
-	// cpos == unitstart + 4 + 2 + 4
-	lsu.AddUint8(1)                // minimum_instruction_length
+	lsu.AddUint8(1) // minimum_instruction_length
+	if buildcfg.Experiment.Dwarf5 {
+		lsu.AddUint8(1) // maximum_operations_per_instruction
+	}
 	lsu.AddUint8(is_stmt)          // default_is_stmt
 	lsu.AddUint8(LINE_BASE & 0xFF) // line_base
 	lsu.AddUint8(LINE_RANGE)       // line_range