diff --git a/compiler/symbol.go b/compiler/symbol.go
index c2007cfd41..e175bdd78d 100644
--- a/compiler/symbol.go
+++ b/compiler/symbol.go
@@ -172,6 +172,12 @@ func (c *compilerContext) getFunction(fn *ssa.Function) (llvm.Type, llvm.Value)
 		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
 		llvmFn.AddAttributeAtIndex(2, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("readonly"), 0))
 		llvmFn.AddAttributeAtIndex(2, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
+	case "runtime.stringFromBytes":
+		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
+		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("readonly"), 0))
+	case "runtime.stringFromRunes":
+		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
+		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("readonly"), 0))
 	case "runtime.trackPointer":
 		// This function is necessary for tracking pointers on the stack in a
 		// portable way (see gc_stack_portable.go). Indicate to the optimizer
diff --git a/transform/testdata/allocs2.go b/transform/testdata/allocs2.go
index 3b08fbc9e4..299df5b213 100644
--- a/transform/testdata/allocs2.go
+++ b/transform/testdata/allocs2.go
@@ -49,6 +49,15 @@ func main() {
 		n4 = n5
 	}()
 	println(n4, n5)
+
+	// This shouldn't escape.
+	var buf [32]byte
+	s := string(buf[:])
+	println(len(s))
+
+	var rbuf [5]rune
+	s = string(rbuf[:])
+	println(s)
 }
 
 func derefInt(x *int) int {