diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index 4d942d037fc..7e1a9adae87 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -441,10 +441,10 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 		// Determine if the callee edge is a for hot callee or not.
 		if base.Flag.PgoProfile != "" && pgo.WeightedCG != nil && v.curFunc != nil {
 			if fn := inlCallee(n.X); fn != nil && typecheck.HaveInlineBody(fn) {
-				ln := pgo.ConvertLine2Int(ir.Line(n))
-				csi := pgo.CallSiteInfo{Line: ln, Caller: v.curFunc, Callee: fn}
+				line := int(base.Ctxt.InnermostPos(n.Pos()).RelLine())
+				csi := pgo.CallSiteInfo{Line: line, Caller: v.curFunc, Callee: fn}
 				if _, o := candHotEdgeMap[csi]; o {
-					pgo.ListOfHotCallSites[pgo.CallSiteInfo{Line: ln, Caller: v.curFunc}] = struct{}{}
+					pgo.ListOfHotCallSites[pgo.CallSiteInfo{Line: line, Caller: v.curFunc}] = struct{}{}
 					if base.Debug.PGOInline > 0 {
 						fmt.Printf("hot-callsite identified at line=%v for func=%v\n", ir.Line(n), ir.PkgFuncName(v.curFunc))
 					}
@@ -873,8 +873,8 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlCalls *[]*ir.Inlin
 	}
 	if fn.Inl.Cost > maxCost {
 		// If the callsite is hot and it is under the inlineHotMaxBudget budget, then try to inline it, or else bail.
-		ln := pgo.ConvertLine2Int(ir.Line(n))
-		csi := pgo.CallSiteInfo{Line: ln, Caller: ir.CurFunc}
+		line := int(base.Ctxt.InnermostPos(n.Pos()).RelLine())
+		csi := pgo.CallSiteInfo{Line: line, Caller: ir.CurFunc}
 		if _, ok := pgo.ListOfHotCallSites[csi]; ok {
 			if fn.Inl.Cost > inlineHotMaxBudget {
 				if logopt.Enabled() {
@@ -1038,8 +1038,8 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlCalls *[]*ir.Inlin
 	}
 
 	if base.Debug.PGOInline > 0 {
-		ln := pgo.ConvertLine2Int(ir.Line(n))
-		csi := pgo.CallSiteInfo{Line: ln, Caller: ir.CurFunc}
+		line := int(base.Ctxt.InnermostPos(n.Pos()).RelLine())
+		csi := pgo.CallSiteInfo{Line: line, Caller: ir.CurFunc}
 		if _, ok := inlinedCallSites[csi]; !ok {
 			inlinedCallSites[csi] = struct{}{}
 		}
diff --git a/src/cmd/compile/internal/pgo/irgraph.go b/src/cmd/compile/internal/pgo/irgraph.go
index 98238823f7f..e6e183cdd22 100644
--- a/src/cmd/compile/internal/pgo/irgraph.go
+++ b/src/cmd/compile/internal/pgo/irgraph.go
@@ -4,9 +4,45 @@
 
 // WORK IN PROGRESS
 
+// A note on line numbers: when working with line numbers, we always use the
+// binary-visible relative line number. i.e., the line number as adjusted by
+// //line directives (ctxt.InnermostPos(ir.Node.Pos()).RelLine()).
+//
+// If you are thinking, "wait, doesn't that just make things more complex than
+// using the real line number?", then you are 100% correct. Unfortunately,
+// pprof profiles generated by the runtime always contain line numbers as
+// adjusted by //line directives (because that is what we put in pclntab). Thus
+// for the best behavior when attempting to match the source with the profile
+// it makes sense to use the same line number space.
+//
+// Some of the effects of this to keep in mind:
+//
+//  - For files without //line directives there is no impact, as RelLine() ==
+//    Line().
+//  - For functions entirely covered by the same //line directive (i.e., a
+//    directive before the function definition and no directives within the
+//    function), there should also be no impact, as line offsets within the
+//    function should be the same as the real line offsets.
+//  - Functions containing //line directives may be impacted. As fake line
+//    numbers need not be monotonic, we may compute negative line offsets. We
+//    should accept these and attempt to use them for best-effort matching, as
+//    these offsets should still match if the source is unchanged, and may
+//    continue to match with changed source depending on the impact of the
+//    changes on fake line numbers.
+//  - Functions containing //line directives may also contain duplicate lines,
+//    making it ambiguous which call the profile is referencing. This is a
+//    similar problem to multiple calls on a single real line, as we don't
+//    currently track column numbers.
+//
+// Long term it would be best to extend pprof profiles to include real line
+// numbers. Until then, we have to live with these complexities. Luckily,
+// //line directives that change line numbers in strange ways should be rare,
+// and failing PGO matching on these files is not too big of a loss.
+
 package pgo
 
 import (
+	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
@@ -14,8 +50,6 @@ import (
 	"internal/profile"
 	"log"
 	"os"
-	"strconv"
-	"strings"
 )
 
 // IRGraph is the key datastrcture that is built from profile. It is essentially a call graph with nodes pointing to IRs of functions and edges carrying weights and callsite information. The graph is bidirectional that helps in removing nodes efficiently.
@@ -131,13 +165,6 @@ func BuildWeightedCallGraph() {
 	WeightedCG = createIRGraph()
 }
 
-// ConvertLine2Int converts ir.Line string to integer.
-func ConvertLine2Int(line string) int {
-	splits := strings.Split(line, ":")
-	cs, _ := strconv.ParseInt(splits[len(splits)-2], 0, 64)
-	return int(cs)
-}
-
 // preprocessProfileGraph builds various maps from the profile-graph. It builds GlobalNodeMap and other information based on the name and callsite to compute node and edge weights which will be used later on to create edges for WeightedCG.
 func preprocessProfileGraph() {
 	nFlat := make(map[string]int64)
@@ -284,7 +311,7 @@ func (g *IRGraph) createIRGraphEdge(fn *ir.Func, callernode *IRNode, name string
 			ir.DoChildren(n, doNode)
 		case ir.OCALLFUNC:
 			call := n.(*ir.CallExpr)
-			line := ConvertLine2Int(ir.Line(n))
+			line := int(base.Ctxt.InnermostPos(n.Pos()).RelLine())
 			// Find the callee function from the call site and add the edge.
 			f := inlCallee(call.X)
 			if f != nil {
@@ -294,7 +321,7 @@ func (g *IRGraph) createIRGraphEdge(fn *ir.Func, callernode *IRNode, name string
 			call := n.(*ir.CallExpr)
 			// Find the callee method from the call site and add the edge.
 			fn2 := ir.MethodExprName(call.X).Func
-			line := ConvertLine2Int(ir.Line(n))
+			line := int(base.Ctxt.InnermostPos(n.Pos()).RelLine())
 			g.addEdge(callernode, fn2, &n, name, line)
 		}
 		return false