diff --git a/src/runtime/extern.go b/src/runtime/extern.go
index b2003ba543..f1f6ea5123 100644
--- a/src/runtime/extern.go
+++ b/src/runtime/extern.go
@@ -78,6 +78,11 @@ It is a comma-separated list of name=val pairs setting these named variables:
 	If the line ends with "(forced)", this GC was forced by a
 	runtime.GC() call.
 
+	harddecommit: setting harddecommit=1 causes memory that is returned to the OS to
+	also have protections removed on it. This is the only mode of operation on Windows,
+	but is helpful in debugging scavenger-related issues on other platforms. Currently,
+	only supported on Linux.
+
 	inittrace: setting inittrace=1 causes the runtime to emit a single line to standard
 	error for each package with init work, summarizing the execution time and memory
 	allocation. No information is printed for inits executed as part of plugin loading
diff --git a/src/runtime/mem_linux.go b/src/runtime/mem_linux.go
index 3436851091..f8f9c53170 100644
--- a/src/runtime/mem_linux.go
+++ b/src/runtime/mem_linux.go
@@ -114,9 +114,29 @@ func sysUnused(v unsafe.Pointer, n uintptr) {
 		atomic.Store(&adviseUnused, _MADV_DONTNEED)
 		madvise(v, n, _MADV_DONTNEED)
 	}
+
+	if debug.harddecommit > 0 {
+		p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
+		if p != v || err != 0 {
+			throw("runtime: cannot disable permissions in address space")
+		}
+	}
 }
 
 func sysUsed(v unsafe.Pointer, n uintptr) {
+	if debug.harddecommit > 0 {
+		p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
+		if err == _ENOMEM {
+			throw("runtime: out of memory")
+		}
+		if p != v || err != 0 {
+			throw("runtime: cannot remap pages in address space")
+		}
+		return
+
+		// Don't do the sysHugePage optimization in hard decommit mode.
+		// We're breaking up pages everywhere, there's no point.
+	}
 	// Partially undo the NOHUGEPAGE marks from sysUnused
 	// for whole huge pages between v and v+n. This may
 	// leave huge pages off at the end points v and v+n
diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index b6c3cbfff4..65e1e0eebc 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -315,6 +315,7 @@ var debug struct {
 	schedtrace         int32
 	tracebackancestors int32
 	asyncpreemptoff    int32
+	harddecommit       int32
 
 	// debug.malloc is used as a combined debug check
 	// in the malloc function and should be set
@@ -344,6 +345,7 @@ var dbgvars = []dbgVar{
 	{"tracebackancestors", &debug.tracebackancestors},
 	{"asyncpreemptoff", &debug.asyncpreemptoff},
 	{"inittrace", &debug.inittrace},
+	{"harddecommit", &debug.harddecommit},
 }
 
 func parsedebugvars() {