diff --git a/BUILD.bazel b/BUILD.bazel
index eef2ff1..1e0cc73 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -412,10 +412,14 @@ cc_binary(
 
 cc_binary(
     name = "benchmarks",
-    srcs = ["evals/benchmarks.cc"],
+    srcs = [
+        "evals/benchmarks.cc",
+        "evals/prompts.h",
+    ],
     deps = [
         ":benchmark_helper",
         "@google_benchmark//:benchmark",
+        "@highway//:hwy",  # base.h
     ],
 )
 
diff --git a/evals/benchmarks.cc b/evals/benchmarks.cc
index 6b90159..5e7cf15 100644
--- a/evals/benchmarks.cc
+++ b/evals/benchmarks.cc
@@ -20,6 +20,7 @@
 
 #include "benchmark/benchmark.h"
 #include "evals/benchmark_helper.h"
+#include "evals/prompts.h"
 
 namespace gcpp {
 
@@ -62,6 +63,20 @@ static void BM_coding_prompt(benchmark::State& state) {
                   state);
 }
 
+static void BM_diff_length_prompt(benchmark::State& state) {
+  gcpp::RunPrompt(GetPrompt(state.range(0)), state);
+}
+
+BENCHMARK(BM_diff_length_prompt)
+    ->Iterations(3)
+    ->Arg(32)
+    ->Arg(64)
+    ->Arg(128)
+    ->Arg(256)
+    ->Arg(512)
+    ->Unit(benchmark::kMillisecond)
+    ->UseRealTime();
+
 BENCHMARK(BM_short_prompt)
     ->Iterations(3)
     ->Unit(benchmark::kMillisecond)
diff --git a/evals/prompts.h b/evals/prompts.h
new file mode 100644
index 0000000..77d5e53
--- /dev/null
+++ b/evals/prompts.h
@@ -0,0 +1,105 @@
+#ifndef THIRD_PARTY_GEMMA_CPP_EVALS_PROMPTS_H_
+#define THIRD_PARTY_GEMMA_CPP_EVALS_PROMPTS_H_
+
+#include "hwy/base.h"
+
+// The input prompts, each named by its token length.
+static const char* Prompt32() {
+  return "In the heart of a bustling marketplace, amidst the vibrant colors "
+         "and lively chatter, there existed a realm where fruits reigned "
+         "supreme. Each fruit, with its unique shape, texture, and flavor, "
+         "held a story waiting to be told.";
+}
+
+static const char* Prompt64() {
+  return "There was the regal Apple, its skin a vibrant red, its flesh a crisp "
+         "white. It was a symbol of knowledge and temptation, reminding all of "
+         "the Garden of Eden and the pursuit of wisdom. The Apple, with its "
+         "sweet and slightly tart taste, was a versatile fruit, enjoyed on its "
+         "own, baked into pies, or transformed into cider. ";
+}
+
+static const char* Prompt128() {
+  return "Beside the Apple stood the cheerful Banana, its curved yellow form a "
+         "beacon of sunshine. The Banana, with its creamy texture and sweet "
+         "flavor, was a source of energy and happiness. It was a fruit that "
+         "brought smiles to faces, whether eaten as a snack, blended into "
+         "smoothies, or used to create delicious banana bread. Across the way, "
+         "the playful Grapes hung in clusters, their translucent green and "
+         "purple orbs glistening like jewels. The Grapes, with their juicy "
+         "flesh and refreshing taste, were a symbol of abundance and "
+         "celebration. They were a fruit that added a touch of elegance to any "
+         "occasion, whether";
+}
+
+static const char* Prompt256() {
+  return "Next to the Grapes, the prickly Pineapple stood tall, its spiky "
+         "exterior concealing a sweet and tangy treasure. The Pineapple, with "
+         "its golden flesh and tropical aroma, was a symbol of hospitality and "
+         "warmth. It was a fruit that transported taste buds to faraway lands, "
+         "whether enjoyed on its own, grilled, or used to create refreshing "
+         "cocktails. And in the corner, the humble Orange shone brightly, its "
+         "citrusy scent filling the air. The Orange, with its juicy segments "
+         "and tangy flavor, was a symbol of vitality and health. It was a "
+         "fruit that invigorated the senses, whether enjoyed as a snack, "
+         "squeezed into juice, or used to create zesty marmalades. ";
+}
+
+static const char* Prompt512() {
+  return "In the marketplace, the fruits coexisted harmoniously, each "
+         "contributing its own unique essence to the vibrant tapestry of "
+         "flavors. They were a reminder that diversity is beautiful, and that "
+         "every fruit, no matter how big or small, has a story to tell. As the "
+         "day progressed, people from all walks of life flocked to the "
+         "marketplace, drawn by the allure of the fruits. There was the young "
+         "child, eyes wide with wonder, reaching for a plump strawberry, its "
+         "bright red hue promising a burst of sweetness. There was the elderly "
+         "couple, sharing a juicy mango, its golden flesh evoking memories of "
+         "their youth. And there was the chef, carefully selecting a variety "
+         "of fruits, their vibrant colors and textures inspiring culinary "
+         "creations that would tantalize taste buds. Among the crowd, a "
+         "storyteller captivated listeners with tales of the fruits' origins "
+         "and symbolism. He spoke of the pomegranate, its ruby-red seeds "
+         "representing fertility and abundance, and the fig, its sweetness "
+         "signifying peace and prosperity. He told of the watermelon, its "
+         "refreshing juice quenching thirst on hot summer days, and the kiwi, "
+         "its vibrant green flesh offering a taste of the exotic. ...As the "
+         "sun began its descent, casting long shadows across the marketplace, "
+         "a hush fell over the crowd.  A young girl, no older than seven, with "
+         "bright eyes and a mischievous grin, approached the storyteller.  "
+         "Clutching a small, bruised apple in her hand, she asked, \"What "
+         "about my apple?  It's not pretty like the others.  Does it have a "
+         "story too?\" The storyteller smiled warmly, taking the apple gently "
+         "from her hand.  \"Ah,\" he began, his voice resonating through the "
+         "square, \"this apple, though seemingly imperfect, holds a story of "
+         "resilience and transformation.  You see, where others may see a "
+         "blemish, we can see a mark of character, a reminder that true beauty "
+         "lies within. He held the apple aloft for all to see.  \"This "
+         "apple,\" he continued, \"has faced the challenges of nature – the "
+         "wind, the rain, perhaps even a hungry bird.  But it has endured, its "
+         "sweetness preserved, its essence intact.  It reminds us that even in "
+         "the face of adversity, we can emerge stronger, our spirits "
+         "unbroken.\"The girl's eyes widened, her smile returning brighter "
+         "than before.  Inspired by the storyteller's words, she took a bite "
+         "of her apple, savoring its sweet, slightly tart flavor.  It was the "
+         "most delicious apple she had";
+}
+
+static HWY_MAYBE_UNUSED const char* GetPrompt(int length) {
+  switch (length) {
+    case 32:
+      return Prompt32();
+    case 64:
+      return Prompt64();
+    case 128:
+      return Prompt128();
+    case 256:
+      return Prompt256();
+    case 512:
+      return Prompt512();
+    default:
+      return Prompt32();
+  }
+}
+
+#endif  // THIRD_PARTY_GEMMA_CPP_EVALS_PROMPTS_H_