diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 2da4e12e6f..05822ff342 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -325,6 +325,7 @@ set(MAIN_SRCS
     script_opt/Expr.cc
     script_opt/Inline.cc
     script_opt/ProfileFunc.cc
+    script_opt/Reduce.cc
     script_opt/ScriptOpt.cc
     script_opt/Stmt.cc
     script_opt/TempVar.cc
diff --git a/src/script_opt/Reduce.cc b/src/script_opt/Reduce.cc
new file mode 100644
index 0000000000..91518bba97
--- /dev/null
+++ b/src/script_opt/Reduce.cc
@@ -0,0 +1,282 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#include "ID.h"
+#include "Var.h"
+#include "Scope.h"
+#include "Expr.h"
+#include "Stmt.h"
+#include "Desc.h"
+#include "ProfileFunc.h"
+#include "Reporter.h"
+#include "zeek/script_opt/Reduce.h"
+#include "zeek/script_opt/TempVar.h"
+
+
+namespace zeek::detail {
+
+
+Reducer::Reducer(Scope* s)
+	{
+	scope = s;
+	}
+
+Reducer::~Reducer()
+	{
+	for ( int i = 0; i < temps.length(); ++i )
+		delete temps[i];
+	}
+
+ExprPtr Reducer::GenTemporaryExpr(const TypePtr& t, ExprPtr rhs)
+	{
+	auto e = make_intrusive<NameExpr>(GenTemporary(t, rhs));
+	e->SetLocationInfo(rhs->GetLocationInfo());
+	return e;
+	}
+
+NameExpr* Reducer::UpdateName(NameExpr* n)
+	{
+	if ( NameIsReduced(n) )
+		{
+		Ref(n);
+		return n;
+		}
+
+	return new NameExpr(FindNewLocal(n));
+	}
+
+bool Reducer::NameIsReduced(const NameExpr* n) const
+	{
+	auto id = n->Id();
+	return inline_block_level == 0 || id->IsGlobal() || IsTemporary(id) ||
+		IsNewLocal(n);
+	}
+
+void Reducer::UpdateIDs(IDPList* ids)
+	{
+	loop_over_list(*ids, i)
+		{
+		IDPtr id = {NewRef{}, (*ids)[i]};
+
+		if ( ! ID_IsReduced(id) )
+			(*ids)[i] = UpdateID(id).release();
+		}
+	}
+
+void Reducer::UpdateIDs(std::vector<IDPtr>& ids)
+	{
+	for ( auto& id : ids )
+		if ( ! ID_IsReduced(id) )
+			id = UpdateID(id);
+	}
+
+bool Reducer::IDsAreReduced(const IDPList* ids) const
+	{
+	for ( auto& id : *ids )
+		if ( ! ID_IsReduced(id) )
+			return false;
+
+	return true;
+	}
+
+bool Reducer::IDsAreReduced(const std::vector<IDPtr>& ids) const
+	{
+	for ( auto& id : ids )
+		if ( ! ID_IsReduced(id) )
+			return false;
+
+	return true;
+	}
+
+IDPtr Reducer::UpdateID(IDPtr id)
+	{
+	if ( ID_IsReduced(id) )
+		return id;
+
+	return FindNewLocal(id.get());
+	}
+
+bool Reducer::ID_IsReduced(const ID* id) const
+	{
+	return inline_block_level == 0 || id->IsGlobal() || IsTemporary(id) ||
+		IsNewLocal(id);
+	}
+
+NameExprPtr Reducer::GenInlineBlockName(IDPtr id)
+	{
+	return make_intrusive<NameExpr>(GenLocal(id.get()));
+	}
+
+NameExprPtr Reducer::PushInlineBlock(TypePtr type)
+	{
+	++inline_block_level;
+
+	if ( ! type || type->Tag() == TYPE_VOID )
+		return nullptr;
+
+	char buf[8192];
+	int n = new_locals.size();
+	snprintf(buf, sizeof buf, "@retvar");
+
+	IDPtr ret_id = install_ID(buf, "<internal>", false, false);
+	ret_id->SetType(type);
+
+	// Track this as a new local *if* we're in the outermost inlining
+	// block.  If we're recursively deeper into inlining, then this
+	// variable will get mapped to a local anyway, so no need.
+	if ( inline_block_level == 1 )
+		new_locals.insert(ret_id.get());
+
+	return GenInlineBlockName(ret_id);
+	}
+
+void Reducer::PopInlineBlock()
+	{
+	--inline_block_level;
+	}
+
+bool Reducer::SameVal(const Val* v1, const Val* v2) const
+	{
+	if ( is_atomic_val(v1) )
+		return same_atomic_val(v1, v2);
+	else
+		return v1 == v2;
+	}
+
+IDPtr Reducer::GenTemporary(const TypePtr& t, ExprPtr rhs)
+	{
+	if ( Optimizing() )
+		reporter->InternalError("Generating a new temporary while optimizing");
+
+	auto temp = new TempVar(temps.length(), t, rhs);
+	IDPtr temp_id = install_ID(temp->Name(), "<internal>", false, false);
+
+	temp->SetID(temp_id);
+	temp_id->SetType(t);
+
+	temps.append(temp);
+	ids_to_temps[temp_id.get()] = temp;
+
+	return temp_id;
+	}
+
+IDPtr Reducer::FindNewLocal(ID* id)
+	{
+	auto mapping = orig_to_new_locals.find(id);
+
+	if ( mapping != orig_to_new_locals.end() )
+		return mapping->second;
+
+	return GenLocal(id);
+	}
+
+IDPtr Reducer::GenLocal(ID* orig)
+	{
+	if ( Optimizing() )
+		reporter->InternalError("Generating a new local while optimizing");
+
+	char buf[8192];
+	int n = new_locals.size();
+	snprintf(buf, sizeof buf, "%s.%d", orig->Name(), n);
+
+	IDPtr local_id = install_ID(buf, "<internal>", false, false);
+	local_id->SetType(orig->GetType());
+
+	new_locals.insert(local_id.get());
+	orig_to_new_locals[orig] = local_id;
+
+	return local_id;
+	}
+
+bool Reducer::IsNewLocal(const ID* id) const
+	{
+	ID* non_const_ID = (ID*) id;	// I don't get why C++ requires this
+	return new_locals.count(non_const_ID) != 0;
+	}
+
+TempVar* Reducer::FindTemporary(const ID* id) const
+	{
+	auto tmp = ids_to_temps.find(id);
+	if ( tmp == ids_to_temps.end() )
+		return nullptr;
+	else
+		return tmp->second;
+	}
+
+Stmt* Reducer::MergeStmts(const NameExpr* lhs, ExprPtr rhs, Stmt* succ_stmt)
+	{
+	// First check for tmp=rhs.
+	auto lhs_id = lhs->Id();
+	auto lhs_tmp = FindTemporary(lhs_id);
+
+	if ( ! lhs_tmp )
+		return nullptr;
+
+	// We have tmp=rhs.  Now look for var=tmp.
+	if ( succ_stmt->Tag() != STMT_EXPR )
+		return nullptr;
+
+	auto s_e = succ_stmt->AsExprStmt()->StmtExpr();
+	if ( s_e->Tag() != EXPR_ASSIGN )
+		return nullptr;
+
+	auto a = s_e->AsAssignExpr();
+	auto a_lhs = a->GetOp1();
+	auto a_rhs = a->GetOp2();
+
+	if ( a_lhs->Tag() != EXPR_REF || a_rhs->Tag() != EXPR_NAME )
+		// Complex 2nd-statement assignment, or RHS not a candidate.
+		return nullptr;
+
+	auto a_lhs_deref = a_lhs->AsRefExprPtr()->GetOp1();
+	if ( a_lhs_deref->Tag() != EXPR_NAME )
+		// Complex 2nd-statement assignment.
+		return nullptr;
+
+	auto a_lhs_var = a_lhs_deref->AsNameExpr()->Id();
+	auto a_rhs_var = a_rhs->AsNameExpr()->Id();
+
+	if ( a_rhs_var != lhs_id )
+		// 2nd statement is var=something else.
+		return nullptr;
+
+	if ( a_lhs_var->GetType()->Tag() != a_rhs_var->GetType()->Tag() )
+		// This can happen when we generate an assignment
+		// specifically to convert to/from an "any" type.
+		return nullptr;
+
+	if ( FindTemporary(a_lhs_var) )
+		{
+		// "var" is itself a temporary.  Don't complain, as
+		// complex reductions can generate these.  We'll wind
+		// up folding the chain once it hits a regular variable.
+		return nullptr;
+		}
+
+	// Got it.  Mark the original temporary as no longer relevant.
+	lhs_tmp->Deactivate();
+	auto merge_e = make_intrusive<AssignExpr>(a_lhs_deref, rhs, false,
+						nullptr, nullptr, false);
+	TrackExprReplacement(rhs.get(), merge_e.get());
+
+	return new ExprStmt(merge_e);
+	}
+                 
+void Reducer::TrackExprReplacement(const Expr* orig, const Expr* e)
+	{
+	new_expr_to_orig[e] = orig;
+	}       
+
+
+const Expr* non_reduced_perp;
+bool checking_reduction;
+
+bool NonReduced(const Expr* perp)
+	{
+	if ( checking_reduction )
+		non_reduced_perp = perp;
+
+	return false;
+	}
+
+
+} // zeek::detail