diff --git a/common/placer1.cc b/common/placer1.cc
index 6da8608a..37294dfd 100644
--- a/common/placer1.cc
+++ b/common/placer1.cc
@@ -46,7 +46,7 @@ NEXTPNR_NAMESPACE_BEGIN
 class SAPlacer
 {
 public:
-    SAPlacer(Context *ctx) : ctx(ctx)
+    SAPlacer(Context *ctx, Placer1Cfg cfg) : ctx(ctx), cfg(cfg)
     {
         int num_bel_types = 0;
         for (auto bel : ctx->getBels()) {
@@ -395,7 +395,7 @@ private:
         if (other != IdString())
             new_dist += get_constraints_distance(ctx, other_cell);
         delta = new_metric - curr_metric;
-        delta += (10 / temp) * (new_dist - old_dist);
+        delta += (cfg.constraintWeight / temp) * (new_dist - old_dist);
         n_move++;
         // SA acceptance criterea
         if (delta < 0 || (temp > 1e-6 && (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / temp))) {
@@ -458,12 +458,13 @@ private:
     const float legalise_temp = 1;
     const float post_legalise_temp = 10;
     const float post_legalise_dia_scale = 1.5;
+    Placer1Cfg cfg;
 };
 
-bool placer1(Context *ctx)
+bool placer1(Context *ctx, Placer1Cfg cfg)
 {
     try {
-        SAPlacer placer(ctx);
+        SAPlacer placer(ctx, cfg);
         placer.place();
         log_info("Checksum: 0x%08x\n", ctx->checksum());
 #ifndef NDEBUG
diff --git a/common/placer1.h b/common/placer1.h
index 477fae56..d8f64b84 100644
--- a/common/placer1.h
+++ b/common/placer1.h
@@ -23,7 +23,12 @@
 
 NEXTPNR_NAMESPACE_BEGIN
 
-extern bool placer1(Context *ctx);
+struct Placer1Cfg
+{
+    float constraintWeight = 10;
+};
+
+extern bool placer1(Context *ctx, Placer1Cfg cfg);
 
 NEXTPNR_NAMESPACE_END
 
diff --git a/ecp5/arch.cc b/ecp5/arch.cc
index 262f43fe..377b8665 100644
--- a/ecp5/arch.cc
+++ b/ecp5/arch.cc
@@ -426,7 +426,7 @@ delay_t Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, de
 
 // -----------------------------------------------------------------------
 
-bool Arch::place() { return placer1(getCtx()); }
+bool Arch::place() { return placer1(getCtx(), Placer1Cfg()); }
 
 bool Arch::route()
 {
diff --git a/generic/arch.cc b/generic/arch.cc
index 1c22dbf7..f9133f9e 100644
--- a/generic/arch.cc
+++ b/generic/arch.cc
@@ -412,7 +412,7 @@ delay_t Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, de
 
 // ---------------------------------------------------------------
 
-bool Arch::place() { return placer1(getCtx()); }
+bool Arch::place() { return placer1(getCtx()\, Placer1Cfg()); }
 
 bool Arch::route() { return router1(getCtx(), Router1Cfg()); }
 
diff --git a/ice40/arch.cc b/ice40/arch.cc
index eff1d9b9..84856402 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -659,7 +659,11 @@ delay_t Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, de
 
 // -----------------------------------------------------------------------
 
-bool Arch::place() { return placer1(getCtx()); }
+bool Arch::place() {
+    Placer1Cfg cfg;
+    cfg.constraintWeight = placer_constraintWeight;
+    return placer1(getCtx(), cfg);
+}
 
 bool Arch::route()
 {
diff --git a/ice40/arch.h b/ice40/arch.h
index 98361132..b9b4f3c5 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -797,6 +797,9 @@ struct Arch : BaseCtx
         }
         NPNR_ASSERT_FALSE("Expected PLL pin to share an output with an SB_IO D_IN_{0,1}");
     }
+
+    float placer_constraintWeight = 10;
+
 };
 
 NEXTPNR_NAMESPACE_END
diff --git a/ice40/main.cc b/ice40/main.cc
index 41d264ad..60f5b444 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -106,6 +106,8 @@ int main(int argc, char *argv[])
         options.add_options()("seed", po::value<int>(), "seed value for random number generator");
         options.add_options()("slack_redist_iter", po::value<int>(),
                               "number of iterations between slack redistribution");
+        options.add_options()("cstrweight", po::value<float>(), "placer weighting for relative constraint satisfaction");
+
         options.add_options()("version,V", "show version");
         options.add_options()("tmfuzz", "run path delay estimate fuzzer");
         options.add_options()("test", "check architecture database integrity");
@@ -318,6 +320,10 @@ int main(int argc, char *argv[])
             ctx->slack_redist_iter = vm["slack_redist_iter"].as<int>();
         }
 
+        if (vm.count("cstrweight")) {
+            ctx->placer_constraintWeight = vm["cstrweight"].as<float>();
+        }
+
         if (vm.count("svg")) {
             std::cout << "<svg xmlns=\"http://www.w3.org/2000/svg\" "
                          "xmlns:xlink=\"http://www.w3.org/1999/xlink\">\n";