diff --git a/lib/expr.ex b/lib/expr.ex
index 1b9ad65..9c3203c 100644
--- a/lib/expr.ex
+++ b/lib/expr.ex
@@ -305,6 +305,27 @@ defmodule AshSql.Expr do
      ), acc}
   end
 
+  defp default_dynamic_expr(
+         query,
+         %Ago{arguments: [duration], embedded?: pred_embedded?},
+         bindings,
+         embedded?,
+         acc,
+         _type
+       ) do
+    {duration, acc} =
+      do_dynamic_expr(
+        query,
+        duration,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc,
+        :duration
+      )
+
+    {Ecto.Query.dynamic(fragment("(?::timestamp - ?)", ^DateTime.utc_now(), ^duration)), acc}
+  end
+
   defp default_dynamic_expr(
          query,
          %StartOfDay{arguments: [value], embedded?: pred_embedded?},
@@ -446,6 +467,27 @@ defmodule AshSql.Expr do
      ), acc}
   end
 
+  defp default_dynamic_expr(
+         query,
+         %FromNow{arguments: [duration], embedded?: pred_embedded?},
+         bindings,
+         embedded?,
+         acc,
+         _type
+       ) do
+    {duration, acc} =
+      do_dynamic_expr(
+        query,
+        duration,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc,
+        :duration
+      )
+
+    {Ecto.Query.dynamic(fragment("(?::timestamp + ?)", ^DateTime.utc_now(), ^duration)), acc}
+  end
+
   defp default_dynamic_expr(
          query,
          %DateTimeAdd{arguments: [datetime, amount, interval], embedded?: pred_embedded?},
@@ -478,6 +520,36 @@ defmodule AshSql.Expr do
      acc}
   end
 
+  defp default_dynamic_expr(
+         query,
+         %DateTimeAdd{arguments: [datetime, duration], embedded?: pred_embedded?},
+         bindings,
+         embedded?,
+         acc,
+         _type
+       ) do
+    {datetime, acc} =
+      do_dynamic_expr(
+        query,
+        datetime,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc
+      )
+
+    {duration, acc} =
+      do_dynamic_expr(
+        query,
+        duration,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc,
+        :duration
+      )
+
+    {Ecto.Query.dynamic(fragment("(?::timestamp + ?)", ^datetime, ^duration)), acc}
+  end
+
   defp default_dynamic_expr(
          query,
          %DateAdd{arguments: [date, amount, interval], embedded?: pred_embedded?},
@@ -509,6 +581,38 @@ defmodule AshSql.Expr do
     {Ecto.Query.dynamic(fragment("(?)", date_add(^date, ^amount, ^to_string(interval)))), acc}
   end
 
+  defp default_dynamic_expr(
+         query,
+         %DateAdd{arguments: [date, duration], embedded?: pred_embedded?},
+         bindings,
+         embedded?,
+         acc,
+         _type
+       ) do
+    {date, acc} =
+      do_dynamic_expr(
+        query,
+        date,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc
+      )
+
+    {duration, acc} =
+      do_dynamic_expr(
+        query,
+        duration,
+        set_location(bindings, :sub_expr),
+        pred_embedded? || embedded?,
+        acc,
+        :duration
+      )
+
+    # `date + interval` is a timestamp in Postgres, so cast back, as Ecto's own
+    # `date_add/3` does.
+    {Ecto.Query.dynamic(fragment("((?::date + ?)::date)", ^date, ^duration)), acc}
+  end
+
   defp default_dynamic_expr(
          query,
          %GetPath{